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SKILLS: How to Navigate off Ben Nevis in Winter

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Whether you're a walker or a climber, the descent from Ben Nevis can present a serious navigational test in winter, and over the years there have been many accidents. In this article, Sean Kelly offers a detailed guide to this potentially hazardous challenge.  

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 TheGeneralist 20 Dec 2021
In reply to UKC/UKH Articles:

> If there is a strong side-wind then this also can effect accurate navigation 

Au contraire, if there's a side wind it's likely to impinge on accurate navigation

In reply to TheGeneralist:

Thanks for spotting that

 TheGeneralist 20 Dec 2021
In reply to Dan Bailey - UKHillwalking.com:

Alas it's all I'm good for. You do the mountain training and write articles.

I'll do the proof reading

( week 4 of 'rona and feeling thoroughly cheesed)

.

In reply to TheGeneralist:

That sounds rough: hope you're better for Christmas

 Steve Crowe 20 Dec 2021
In reply to UKC/UKH Articles:

I can remember one wild winter day sitting on the summit of The Ben. When some people joined us at the top, they had set off down a while ago and somehow managed to walk in a full circle back to the top! I had all the bearings and pacing on a crib sheet in my pocket. As I led us all off in a complete whiteout more climbers joined us and eventually I was leading about a dozen mountaineers down. At one point two lads suddenly disappeared off down number four gully. They were taking the shortcut back to the CIC hut while the rest of us headed towards Red Burn and shortly we were below the cloud base and into better visibility. 

In reply to UKC/UKH Articles:

This is precisely the content that makes this forum awesome! Thank you.

(Bookmarked for the next rare occasion I make it that far north again)

 GrahamD 21 Dec 2021
In reply to UKC/UKH Articles:

Topping out on a climb in crap conditions, we felt smug having a brand new GPS with us and promptly set off without unpacking the map and compass.  Very quickly the GPS packed up and we hadn't a clue where we were ! We hadn't gone up to the summit from the top of the route so no cairns in sight.

Luckily a speculative wander across the plateau brought is sight of a couple of walkers who did know where they were and where they were going.

Probably a few morals to this story but I think "don't be complacent" is probably the most succinct. 

 Sean Kelly 21 Dec 2021
In reply to UKC/UKH Articles:

Just noticed that the attached Harvey's maps of the summit do not mark Five Finger Gully or the Red Burn. Detail seems to change with new editions. However all is not lost as they are clearly defined in the Scottish Winter Climbs guide from the SMC, p.108 to be precise. 

 Harry Jarvis 21 Dec 2021
In reply to Sean Kelly:

> Just noticed that the attached Harvey's maps of the summit do not mark Five Finger Gully or the Red Burn. Detail seems to change with new editions. However all is not lost as they are clearly defined in the Scottish Winter Climbs guide from the SMC, p.108 to be precise. 

See also the Mountaineering Scotland webpage, which shows Five Finger Gully, but not the Red Burn. This appears to be an earlier edition of the Harvey's map. 

https://www.mountaineering.scot/activities/hillwalking/ben-nevis

I wonder why they choose to omit such details? 

 mattyP 21 Dec 2021
In reply to Sean 

is it not because the extract is from the Harvey Superwalker not the BMC mountain map?

I think the mountain map has shed loads of crag/gulley detail which the superwalker omits. 

 brian_m 21 Dec 2021
In reply to UKC/UKH Articles:

> Don't forget to make the correct adjustment for the magnetic variation. Magnetic north is estimated to be 2 degrees 9 mins west of grid north British National Grid at this location in July 2021

A good article, thanks, but I think you've got the magnetic variation wrong. The figure you give is the angle between Magnetic North and True North.

From a fairly recent OS 1:50,000 map it gives Magnetic North as 0 degrees 55 minutes West of Grid North for July 2016 with an anual change of 12 minutes East. This would give 0 degrees 5 minutes East for July 2021. This is effectively zero in terms of mountain navigation and will be for a few years.

You also claim that the change in Variation is 1/2 degrees in 6 years. This is also wrong. It's much closer to 1 degree in 5 years.

The first website that you link to gives the angle between Magnetic and True North. The second gives 0 degrees 16 minures East which is very close to what I worked out from a 5 year old map.

 99ster 22 Dec 2021
In reply to brian_m:

The estimated annual change corrections given on most of these maps cannot be applied reliably if the maps are more than a few years old since the secular variation also changes with time in an unpredictable manner.  Go here to get up-to-date values for magnetic declination:   https://www.magnetic-declination.com/
The current magnetic declination for Fort William is -2 deg (West).  Not a huge amount, but still a value that you can measure on a compass, and one that you should factor in when navigating, and definitely not "effectively zero".  Yes, southern England now has pretty much zero magnetic declination, but that's not where Ben Nevis is located.

> A good article, thanks, but I think you've got the magnetic variation wrong. The figure you give is the angle between Magnetic North and True North.

> From a fairly recent OS 1:50,000 map it gives Magnetic North as 0 degrees 55 minutes West of Grid North for July 2016 with an anual change of 12 minutes East. This would give 0 degrees 5 minutes East for July 2021. This is effectively zero in terms of mountain navigation and will be for a few years.

> You also claim that the change in Variation is 1/2 degrees in 6 years. This is also wrong. It's much closer to 1 degree in 5 years.

> The first website that you link to gives the angle between Magnetic and True North. The second gives 0 degrees 16 minures East which is very close to what I worked out from a 5 year old map.

3
 lithos 22 Dec 2021
In reply to 99ster:

sorry brian is correct.

there are 3 norths,  True (north pole), Magnetic(where compas points) Grid (OS grid projection)

'magnetic declination' is diff between mag and true norths (~2) (both sites confirm this figure)

OS Grid map users (us) are interested in mag vs grid (~0.2) aka 'Grid Magnetic Angle'

 jpicksley 22 Dec 2021
In reply to brian_m:

I think you're right. The paragraph on magnetic variation is confused and could do with being rewritten. The key point though appears correct which is that one should add nothing to the grid bearing of 231 as magnetic variation is presently essentially zero.

Even when variation was upwards of 2 degrees I never bothered with it though and have never noticed my bearings being off. After trying it a few times I determined it wasn't worth adding. I think this is probably due to the whole process of taking a bearing being error prone when done under stress and in difficult circumstances.

 jpicksley 22 Dec 2021
In reply to UKC/UKH Articles:

I think this is a good article but I have another point to raise for discussion. I don't like the pacing chart and actually think it's a bad device. I've never come across underfoot terrain that is consistent across 100m sections. Terrain is constantly changing and therefore so does my pacing. What I mean is: I count 65 doubles to a flat clear 100mts; when I'm pacing I just add extra paces in when I feel I haven't taken a normal stride and duplicate the last number I was just at. So I only ever count to 65 but I may actually have taken many more. This is much more dynamic and responsive to the terrain and very accurate. I've also never come across a situation where I count less than 65. I don't over stride and think that would be a very unusual  thing to do.

Just my opinion on the matter. I'd be interested in other opinions as every day's a school day.

 Lankyman 22 Dec 2021
In reply to jpicksley:

I really am a Lankyman - I do 53 double paces to a 100m leg (smooth, level going). I also 'fiddle' it for slopes and rougher ground.

In reply to UKC/UKH Articles:

A friend of mine was recently telling me he had to do exactly this, getting down from the summit in whiteout. Pacing bearing and standing still sending partner out in front as far as communication/sight (not very far!) then telling them left/right according to compass sight. Then walking to them and repeating until they found the cairns of the zigzag. He reckoned if they hadn't learned and practiced that a few days before they'd have been in deep "it"

 jpicksley 22 Dec 2021
In reply to Lankyman:

53? Bit taller than me then! I prefer to think of it as "dynamic pace adjustment" rather that "fiddle".

Post edited at 10:31
In reply to lithos:

I'm sceptical as hell about this. First I don't believe a normal person can use a compass that accurately in poor conditions, 1 degree or half a degree in 360 that's a fraction of a percent.  Second, I don't believe the compass is actually anything like that accurate at finding north in real world conditions e.g. if you have a phone in your pocket with neodynium magnets for the speakers.  Third, I don't believe people can pace accurately over broken ground in bad conditions and fourth if they break it up into many short legs the errors will accumulate.

If you want to know where you are get a GPS and measure location directly.  If you need it to work on a mountain in winter get a GPS rated for those conditions.  It is 2021 the map and compass should be the backup not the primary device.

Post edited at 12:23
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 Ciro 22 Dec 2021
In reply to tom_in_edinburgh:

> If you want to know where you are get a GPS and measure location directly.  If you need it to work on a mountain in winter get a GPS rated for those conditions.  It is 2021 the map and compass should be the backup not the primary device.

Using a map and compass to navigate in the hills teaches you a lot more about how to deal with emergency than a GPS ever will, and if you don't practice it you might panic the day your GPS gets lost or damaged.

Getting slightly lost because you've wandered off your bearing, and being able to work out from the terrain where you must be, and figure out a bearing that will take you safely back to your path at a recognisable point is a valuable skill.

 jpicksley 22 Dec 2021
In reply to tom_in_edinburgh:

> I'm sceptical as hell about this. First I don't believe a normal person can use a compass that accurately in poor conditions, 1 degree or half a degree in 360 that's a fraction of a percent.  Second, I don't believe the compass is actually anything like that accurate at finding north in real world conditions e.g. if you have a phone in your pocket with neodynium magnets for the speakers.  Third, I don't believe people can pace accurately over broken ground in bad conditions and fourth if they break it up into many short legs the errors will accumulate.

> If you want to know where you are get a GPS and measure location directly.  If you need it to work on a mountain in winter get a GPS rated for those conditions.  It is 2021 the map and compass should be the backup not the primary device.

Haha! I must be a luddite. I love the map and compass. Much more interesting than a gps (and I do have a gps for redundancy and the InReach facility but it's boring to use for navigation) and definitely my primary choice. To address a couple of points directly. I know I can pace accurately over broken ground in difficult conditions. I know I can follow a bearing in difficult conditions and that the compass is correct. I've done these things very accurately multiple times over the years in bad visibility, white outs and the dark. So you're  basically wrong about those issues. Sorry.

In reply to CantClimbTom:

sending partner out in front as far as communication/sight (not very far!) then telling them left/right according to compass sight

you can make it faster by the front man turning 180 and back bearing on you he will move himself into line then pull you up / wave you forward 

In reply to jpicksley:

> Haha! I must be a luddite. I love the map and compass. Much more interesting than a gps (and I do have a gps for redundancy and the InReach facility but it's boring to use for navigation) and definitely my primary choice. To address a couple of points directly. I know I can pace accurately over broken ground in difficult conditions. I know I can follow a bearing in difficult conditions and that the compass is correct. I've done these things very accurately multiple times over the years in bad visibility, white outs and the dark. So you're  basically wrong about those issues. Sorry.

1. If the conditions are dangerous it isn't about fun, it's about safety.  So use the best equipment you have.

2. Have you actually measured how accurately you can pace?  I'm not saying people can't pace or follow bearings accurately enough so that with some other heuristics it isn't possible to navigate.  Clearly it is.  What I'm saying is that the precision being used in instructions like follow a bearing of 181degrees or worrying about a degree or two of magnetic declination is ridiculous.  It's like telling someone to cut a 0.183cm long strip of paper when all they have is scissors and a ruler.

1% of 360 degrees is 3.6 degrees. I'd be very surprised if people were getting close to 1% accurate in measuring and following a bearing on top of a mountain.

2
In reply to jpicksley:

A compass can go wrong

I spent a night in the Woolpack (Boot) when trying to go back to Borowdale  it was 180 out and by the time I was out of mist darkness was close 

I take the point that any compass we use is not to a degree or so 

In reply to tom_in_edinburgh:

> 1% of 360 degrees is 3.6 degrees. I'd be very surprised if people were getting close to 1% accurate in measuring and following a bearing on top of a mountain.

In a white-out, got to agree with you.

On a clear day with a sighting compass I reckon it's doable, but of course the chances of you needing to do this on a clear day are pretty close to zero.

 jpicksley 22 Dec 2021
In reply to tom_in_edinburgh:

> 1. If the conditions are dangerous it isn't about fun, it's about safety.  So use the best equipment you have.

> 2. Have you actually measured how accurately you can pace?  I'm not saying people can't pace or follow bearings accurately enough so that with some other heuristics it isn't possible to navigate.  Clearly it is.  What I'm saying is that the precision being used in instructions like follow a bearing of 181degrees or worrying about a degree or two of magnetic declination is ridiculous.  It's like telling someone to cut a 0.183cm long strip of paper when all they have is scissors and a ruler.

> 1% of 360 degrees is 3.6 degrees. I'd be very surprised if people were getting close to 1% accurate in measuring and following a bearing on top of a mountain.

1. It's always about fun. If it isn't fun you're doing it wrong Map and compass is more interesting and a good skill to maintain. The accuracy comes from a lot of practice which you don't get if you leave them in the rucksack and use a gps. You don't need any skill to use a gps and you don't need to practice hence why it's not my primary tool but there as a backup. In my opinion using 4he map and compass are key mountain skills and useful to maintain but it takes patience, skill and practice.

2. I think we covered magnetic declination/variation earlier. Navigation is about heuristics. You don't just use one technique. You use what you need at the time. I agree that there is inherent error in taking a bearing and measuring/pacing but I can guarantee you it's definitely possible to be highly accurate (and much more fun and satisfying).

See you out there. Or not if it's a white out.

In reply to Michael Hood:

> On a clear day with a sighting compass I reckon it's doable, but of course the chances of you needing to do this on a clear day are pretty close to zero.

Agreed.  If you can see a long way then you can get high accuracy (ignoring the potential for magnetic items like cellphones you might be carrying influencing the compass), but if you could see a long way you could follow the tourist path.

Post edited at 14:13
 jpicksley 22 Dec 2021
In reply to Name Changed 34:

Agreed. That's why I carry a spare and a gps and why I sense check my bearings. It's all about process and having multiple tools and skills.

In reply to tom_in_edinburgh:

> What I'm saying is that the precision being used in instructions like follow a bearing of 181degrees or worrying about a degree or two of magnetic declination is ridiculous.

Have you come off the top of Ben Nevis in winter in poor visibility? Or done some other "serious risk" navigation task that's similar? I'm still quite proud of coming off Aonach Beag down to the col and over Aonach Mor back to the ski tows in a storm and white out conditions about 25 years ago. You have to change bearings a number of times and pace - we used a rope for some sections. What you say sounds sensible, but whatever the level accuracy that is needed, plenty of us have obviously reached it because we've got off mountains in poor visibility.

I use GPS and OS maps on my phone plenty now, but at least with my set up what it is best for is confirming your position - my phone and the OS maps app can't point you in the right direction. I've been asked twice now in recent winters which way to go by people in cloud on the top of Helvellyn who were using GPS on their phones to 'navigate'. When there no are paths visible because of snow and visibility is poor, without a compass people make mistakes even in trying to go back the way they came from.

 jpicksley 22 Dec 2021
In reply to tom_in_edinburgh:

I suspect the naysayers will not believe it's possible until you see someone do it. I did exactly this on Sunday and Monday nights on the Cairngorm plateau in the dark. I guarantee you it's possible.

In reply to TobyA:

> Have you come off the top of Ben Nevis in winter in poor visibility? Or done some other "serious risk" navigation task that's similar?

I've been in white out conditions on smaller hills and been extremely impressed with the GPS on a phone.  I followed a path which was under snow to the point it was invisible just using the GPS map for maybe a kilometer in the Pentlands and I was probably no more than a metre off at any point.  No way was I going to pull out the map and compass when the GPS was making it as easy as keeping a little blue dot over a path on the map.

I wouldn't rely on a phone GPS on Ben Nevis because they're not designed for very low temperature and the touch screen is no use in a snowstorm.  

1
In reply to jpicksley:

> I suspect the naysayers will not believe it's possible until you see someone do it. I did exactly this on Sunday and Monday nights on the Cairngorm plateau in the dark. I guarantee you it's possible.

I'm not saying it isn't possible to navigate with a map and compass and a few reasonable heuristics.  Quite obviously it is possible.

What I'm saying is the instructions for getting off Ben Nevis should be more realistic in terms of the accuracy of the measurements they are giving relative to the capability of the equipment.

2
 jpicksley 22 Dec 2021
In reply to tom_in_edinburgh:

> No way was I going to pull out the map and compass when the GPS was making it as easy as keeping a little blue dot over a path on the map.

Soulless

1
 jpicksley 22 Dec 2021
In reply to tom_in_edinburgh:

> I'm not saying it isn't possible to navigate with a map and compass and a few reasonable heuristics.  Quite obviously it is possible.

> What I'm saying is the instructions for getting off Ben Nevis should be more realistic in terms of the accuracy of the measurements they are giving relative to the capability of the equipment.

I'm missing the point then. If the bearing is 231 and the distance is 150mts what else should be said? That's what you need to know. How accurate you are is up to you. I thought you were saying it's not possible to be accurate enough using pacing and a bearing so use a gps. I disagree with that. Have I got you wrong?

In reply to Michael Hood:

I’ve navigated off Ben Nevis in a white out, with wind so strong that we had to crawl and mostly look down to avoid being blinded. Compass was fine. Knowing what to do and the correct bearings was what was important.

In reply to jpicksley:

If it was me I'd cut out all the stuff about magnetic declination, call it 230 degrees and be clear you were probably going to be off a bit at the end because of the achievable accuracy in pacing and following a bearing.

4
 jpicksley 22 Dec 2021
In reply to tom_in_edinburgh:

> If it was me I'd cut out all the stuff about magnetic declination, call it 230 degrees and be clear you were probably going to be off a bit at the end because of my achievable accuracy in pacing and following a bearing.

Fixed that for you. I agree to ignoring magnetic variation in the context of grid and magnetic north's. Enjoyed our debate. Take care out there, Mr tom_in_edinburgh.

1
 colinakmc 22 Dec 2021
In reply to UKC/UKH Articles:

Map & compass for me. When I did my ML training a few years ago at Glenmore our instructor was using a GPS to check our accuracy on a bearing though; what it uncovered was that in thick weather folk were weaving about even when they thought they were following the bearing. Only myself & one other were doing the micro nav thing of picking a boulder or whatever, on the bearing but a  few metres away, walking to it then picking another one.

Harder in a whiteout, hence the snowball/rucksack/ partner practice.

My electronic gizmo stays in the bag, only used for confirmation of position.

In reply to colinakmc:

Another map and compass user here (and “survivor” of numerous whiteouts/descents in the dark).

Has someone hacked TominEdinburgh’s account though? No mention at all of how much better navigation is in Scotland. 

1
In reply to UKC/UKH Articles:

Last time I went up Ben Nevis (in May, on a clear day) two friends and I did it via CMD ridge. We met our two less experienced walking friends who'd come up the Pony Track. They got lost on that at one point. We all descended via the Pony Track and I asked our two friends to point out where they'd gotten lost. It was at the end of one of the zig-zags. I literally stood there lost for words! No amount of "er...but it's like a paved path...why did you not just follow it??" could elicit a sensible response, just "well, we just carried on walking..." (off the end of a zig zag). Suffice to say they'd never go anything that requires knowing the difference between types of `north'...

 65 22 Dec 2021
In reply to tom_in_edinburgh:

> I'm sceptical as hell about this. First I don't believe a normal person can use a compass that accurately in poor conditions, 1 degree or half a degree in 360 that's a fraction of a percent.  Second, I don't believe the compass is actually anything like that accurate at finding north in real world conditions e.g. if you have a phone in your pocket with neodynium magnets for the speakers.  Third, I don't believe people can pace accurately over broken ground in bad conditions and fourth if they break it up into many short legs the errors will accumulate.

I've navigated myself to and off several featureless summits in thick clag by pacing and using a compass, sighting lines through stones ahead of me. I've always been close enough within the available visibility. I did have a period at work where I was using pacing to measure things up to 50m, so I've got a reasonable idea of what my paces are like even on uneven ground. From memory I paced myself over 400m to the summit of Geal Charn (Monadhliath) with less than 20m error. Obviously pacing goes down the pan if you're flogging over or around lots of outcrops or hags. I've also navigated my way across Cairngorm in the dark and heavy snow with my less navigationally confident partner out in front with me telling him left or right. This was with about 10m of visibility. It does require total attention to details and awareness of the variables you describe.

> If you want to know where you are get a GPS and measure location directly.  If you need it to work on a mountain in winter get a GPS rated for those conditions.  It is 2021 the map and compass should be the backup not the primary device.

I agree that GPS is the way to go, but the map and compass is still key, in the same way that being self-responsible is still relevant even though one can easily call for a rescue from a mobile phone.

In reply to jpicksley:

> Fixed that for you. I agree to ignoring magnetic variation in the context of grid and magnetic north's. Enjoyed our debate. Take care out there, Mr tom_in_edinburgh.

Let's say you can see 20m through the snow and you are looking at a person and trying to take a bearing to that person you'll have a 0.4 degree difference depending on whether you aim at one side of their face or the other.

Walking on a bearing accurate to 1 degree in bad visibility is fantasy unless you are some kind of ninja.

1
In reply to 65:

>  I paced myself over 400m to the summit of Geal Charn (Monadhliath) with less than 20m error. Obviously pacing goes down the pan if you're flogging over or around lots of outcrops or hags.

20m / 400m is 5% and I think that is pretty good going.

I've no problem with people with navigating with map and compass although I'd prefer to use a GPS but I think the description of how to navigate off Ben Nevis should be more realistic about the achievable accuracy and the uncertainty which will accumulate.

 jpicksley 22 Dec 2021
In reply to tom_in_edinburgh:

In your white out example I know I can navigate accurately on my own. I've hit cairns exactly in this last spell of full snow cover over hundreds of metres but I'm guessing this is all to no avail as you clearly don't believe me. That's OK. You don't know me.

Interestingly, I have been called a ninja pacer and am known as "Tracker Picksley" amongst friends. I've come to the conclusion that my partner is right, I'm weird. I love navigation. I practice everytime I'm out. Honestly, it is possible but you have to practice a lot.

I think 5% is good in general but I wouldn't be happy with it. But I actually think the idea of a % is flawed. Required accuracy depends on visibility in my humble.

Anyway, pointless to go on as you clearly think it's not possible.

4
 jpicksley 22 Dec 2021
In reply to jpicksley:

Oh and my dearly recently departed father was a national standard orienteer, so perhaps it's in the blood.

1
 Sean Kelly 22 Dec 2021
In reply to UKC/UKH Articles:

4 Peaks Sound Walk

A treat on Christmas Day for those not averse to listening to BBC R3, when Horatio Clare travels over the four highest peaks of the different parts that make up the UK. And surprise, surprise, he kicks off with Ben Nevis. Obviously the whole program will be interspersed with music. Catch the link here on...

https://www.bbc.co.uk/programmes/m0012rd7

In reply to tom_in_edinburgh:

All well and good, but not the reality of how you navigate in the real world. The compass is only one of the tools used to navigate accurately, also the need to have an exact location is often not necessary to return to safe ground.

The assessment criteria for a winter mountain leader for example is to be able to identify the are you are in within 100m². However in poor condition this could be 200m² or 25m² in good conditions.

In reply to tom_in_edinburgh:

> I've no problem with people with navigating with map and compass although I'd prefer to use a GPS but I think the description of how to navigate off Ben Nevis should be more realistic about the achievable accuracy and the uncertainty which will accumulate.

Does your gps show you the direction you're meant to be going though? You can see where you are on the map, but how do you know where to go next without a bearing to follow? Obviously when you're on a footpath you just follow the path, and from time to time check the map on your phone to see how far you've got - indeed that's exactly what I was doing last night walking up onto the moors to camp at about 11 pm. I had a map an compass in my bag but that's where it stayed. But on the summit plateau of the Ben, in snow and with either no footprints or lots of footprints going in various directions, I wouldn't know which way to go.

You can get similarly confused with a compass if you forget if it's the red end or white end that points north! Some friends did exactly that walking the five sisters of Kintail in snow, they had some food on the top of one peak, must have got disoriented a bit so checked the compass and marched off back the way they had come without realising it. It took them hours can getting completely lost before they saw lights in a bothy I think it was and found out where they were. I was driving up and down the glen with some other mates looking for them or lights on the hill and were just about to go to the Claunie and call mountain rescue when we found them on the road!

In reply to tom_in_edinburgh:

I think it might be useful to know how accurate you need to be to avoid the dangers coming off the top of the Ben.

E.g. 231 for 150m. If you walk on 225 will you still be ok, how about 220, or 240? What are the error bounds on the 150m, if you only do 130m and then go to 282 will you be ok or will you walk off the N face? How about 170m, will you then go into the top of 5-finger on 282? etc.

Knowing how accurate you have to be in various situations (but mainly knowing where higher accuracy is vital), is useful information to have.

In reply to jpicksley:

> In your white out example I know I can navigate accurately on my own. I've hit cairns exactly in this last spell of full snow cover over hundreds of metres

In my example of coming back over Aonach Mor in a storm many years ago, my mate Ed was 50 mtrs ahead of me on the rope and I was telling him which way to go by my compass as there was nothing else to sight off and I remember him stopping turning around and pulling his scarf down from where it was up under his goggles, and I could just see this big cheesy grin. I had no idea why, so caught up with him and there straight ahead was the summit cairn, we had hit it pretty perfectly, and from there it was just one more straight bearing to the summit tows of the ski areas and a walk down the ski slopes. It was one of those "so this does really work" and "we're actually quite good at this" moments!

 kwoods 22 Dec 2021
In reply to TobyA:

Your post sums it up well for me, I don't see what the bother and arguing is, if good with a map and compass you can hit tiny objects in a whiteout across many hundreds of metres. If you can't do that already, you might never get good at it if you keep reaching for the GPS.

Also works for solo travel, I've never needed to send a mate ahead to sight.

In reply to Michael Hood:

The cheap answer is  It’s depends on the cornice on Gard a loo 

 jpicksley 22 Dec 2021
In reply to Alex Riley:

Interesting. I'd have thought it should be the other way round. The worse the visibility the closer you need to be to see the feature.

 jpicksley 22 Dec 2021
In reply to TobyA:

Don't get that feeling with a gps

In reply to TobyA:

> Does your gps show you the direction you're meant to be going though? 

Usually you just need to walk a few steps and then it will figure out your direction of movement.  Modern phones have an electronic compass and an accelerometer built in as well as the GPS receiver and cellphone connection and unlike a handheld compass and a phone in your chest pocket the electronic compass is calibrated to take account of the magnets in the phone.   

The combination of multiple readings from the GPS as you move, estimation of location based on cellphone signals, the compass and the accelerometer detecting when your velocity changes is enough to calculate the direction you are moving.  The software can even dead reckon your position and velocity in a similar way to a person with map and compass if they lose GPS signals for a while - that's how they deal with tunnels or an area between tall buildings where line of site to the satellites is lost.

In reply to jpicksley:

That's true, but often in winter the feature is a change in slope angle or shape.

 jpicksley 23 Dec 2021
In reply to Alex Riley:

I don't understand why the type of feature makes a difference to accuracy.

Also, are you saying that as long as you're within, say, 100m2, you don't have to know exactly where you are, just that you think you're there or nearly there? Not sure I'm phrasing that question well. I mean, you can be anywhere within 100m2 and not have to know exactly where you are, I.e  that you may or may nor be at the feature but you know you're near?

And a follow-up if you don't mind please. What's the requirement for summer ML?

Post edited at 08:20
 Mike-W-99 23 Dec 2021
In reply to jpicksley:

> And a follow-up if you don't mind please. What's the requirement for summer ML?

Been a while but 25m sounds familiar? (1mm on the 1:25k)

 summo 23 Dec 2021
In reply to Mike-W-99:

> Been a while but 25m sounds familiar? (1mm on the 1:25k)

It depends, if it's a definitive feature you should be on the money. A re-entrant roughly within it, spur on it etc... but the real test is on the next leg if any slight errors are spotted and plans adjusted, rather than compounded. No assessor expects folk to be more precise than the scale of the map and the mapped features, as it's impossible.

Making a navigational error and going to the slightly wrong location isn't an instant fail at summer ML, failing multiple times to realise you were wrong and not relocating would be. 99% of assessors will go out on a night nav for the 2nd night on camp to give a candidate every chance possible to prove their skills if they were in doubt. 

Post edited at 09:17
 Howard J 23 Dec 2021
In reply to UKC/UKH Articles:

I think the world is divided into those for whom navigation is an enjoyable exercise in its own right which they take pleasure from practising even (or perhaps especially) in severe conditions, while for others it is a necessary evil in order to get down safely.  

I must admit I fall into the latter camp.  When I am battling in severe conditions I just want to get down without additional faff.  We now have reliable GPS technology, so why not use it?  Of course technology can fail, and will usually do so at the most inconvenient moment, and I always carry map and compass as well but these are for back-up.  However situations like that are fairly unusual in the British hills, and more often than not a high degree of accuracy is not needed simply to come down into the right valley.

In reply to tom_in_edinburgh:

> Usually you just need to walk a few steps   

Not necessarily the best idea when try to avoid a cornice.

> and then it will figure out your direction of movement.  Modern phones have an electronic compass

Mine doesn't (Moto G8, last year, about 200 quid). I've got plenty of compasses from down the years so that's ok.

I'm not sure what you would use to take a bearing off your OS map app either. Carry a protractor in your pocket? 🤨 If you have pre-logged a route, does it give it to you in bearings? It doesn't on my phone.

The OS app is also quite buggy, it's getting better but still not perfect. I have in the past given up on it and just used my paper map. That alone seems like a good reason to have both. If your map blows away your phone is a lot better than nothing, and vice versa (I had my phone blown out of my hand before, fortunately landing in snow and no damage).

In reply to Howard J:

The problem with using GPS like this, unless you have a very close eye on your GPS and whip the map and compass out as soon as you realise that the GPS has failed / lost comms with the satellites, is that its often too late.  Before you've realised there is a problem you're in no man's land without a clue where you are. With snow on the ground, no distinguishable features to navigate off and poor visibility you are potentially in deep trouble. Fine perhaps if you're in a pair and one person is using a GPS and the other constantly referring to the compass and pacing.

Post edited at 09:49
 Harry Jarvis 23 Dec 2021
In reply to TobyA:

> Mine doesn't (Moto G8, last year, about 200 quid). I've got plenty of compasses from down the years so that's ok.

> I'm not sure what you would use to take a bearing off your OS map app either. Carry a protractor in your pocket? 🤨 If you have pre-logged a route, does it give it to you in bearings? It doesn't on my phone.

> The OS app is also quite buggy, it's getting better but still not perfect. I have in the past given up on it and just used my paper map. That alone seems like a good reason to have both. If your map blows away your phone is a lot better than nothing, and vice versa (I had my phone blown out of my hand before, fortunately landing in snow and no damage).

Other digital maps are available. I use MemoryMap, and it has proved more than adequate over a number of years. I used to use it with a standalone handheld GPS unit, but have more recently I have been happy to use my phone - it has a bigger screen, using the phone reduces the amount of faff, I have never had a problem with the phone losing GPS signals, and I always make sure the phone is fully charged before I set out. It's been absolutely failsafe. 

I do sometimes wonder if those who complain about the use of GPS technology have ever actually tried it. 

In reply to Harry Jarvis:

> I do sometimes wonder if those who complain about the use of GPS technology have ever actually tried it. 

Yes I have. Yes I do use a GPS as a backup to a map and compass. No, it most definitely has not been failsafe in the past: I relied too heavily on my GPS on a night leg of the Bob Graham Round on the Helvelyn ridge in poor conditions. I had one person supporting who at the time didn't know the leg well and so I was navigating myself (my own BG round). I had hoped the GPS would allow me to just run and make for a faster time - I was aiming for a 19 hour round.  It lost all comms after Great Dodd, we drifted off the ridge and hadn't got a clue where we were. I think this happened twice (it picked up a signal briefly before losing it again) and by the end of that leg I was 2.5 hours down on my schedule as a result. Mistakes made and a number of lessons well and truly learned.

In reply to jpicksley:

My point is that 100% accuracy isn't required to navigate to safety.

With the 100m its a guideline for assessment (but gives an idea of accuracy needed), so within 100m basically. If the navigation point is spot height or something obvious you can be dead on with accuracy, if its something like a change in slope angle, ridge or any of the broad features you might use to navigate in winter then less so. 

Sorry if that doesn't quite make sense, I'm on day three with a newborn

Minimum requirements :

Summer ML (assessment)

40 Quality Mountain Days 

Done ML Training

8 Nights camping at least 4 of which are wild camps

Walked in three different mountain regions.

Winter ML (assessment)

Summer ML Assessment

WML Training

Three different areas

40 Winter QMDS

10 Grade 1 winter routes

 Howard J 23 Dec 2021
In reply to Graham Briffett:

In a critical situation such as coming off the Ben where precise navigation is vital I would be keeping a very close eye on the GPS, and depending on the conditions I might use a compass as well.  However I would expect to find that the GPS would be more accurate than compass and pacing.  Most other situations don't require that level of accuracy.

I don't think I've ever lost satellite signal for more than a few seconds, at least so far as I am aware, and I've never found it has misled me.  My only experience of GPS becoming inaccurate has been in forests or close to big cliffs.  The greatest concern is batteries running out, but I carry spares. Of course it could fail completely although this is unlikely, but before it did I should still have a rough idea of where I am, and up to then it will probably have allowed me to move faster than following compass bearings. I also have a phone which will give me a position, although that is perhaps more vulnerable to the conditions, and an altimeter on my watch which can also give some clues.  The GPS is just part of a system - I don't rely on it entirely, but most of the time it can be trusted to be accurate.

Whatever you use to navigate, you still have to be alert to changes in terrain and the sixth sense which tells you you're going wrong (although I find that often it's mistaken, but it does at least prompt me to check)

 GrahamD 23 Dec 2021
In reply to Graham Briffett:

My experience precisely. 

In reply to Harry Jarvis:

> Other digital maps are available.

Of course, and so are different phones and standalone GPS units - they are also all considerably more expensive than a map and compass.

Have you navigated off the top of the Ben (or similar dog-leg necessitated terrain) in poor weather in winter with the set up you are using now? Does your phone and the app give you a directional arrow to walk on? And in such conditions are you happy to not take a map and compass with you?

> I do sometimes wonder if those who complain about the use of GPS technology have ever actually tried it. 

I'm not complaining. Like I've said I think it's great having my position confirmed on an OS map on my phone. A few years ago I was on the Ben in winter for the first time in about 15 years. The summit was above the cloud and gorgeous but we dropped back into the cloud to get to No. 3. I was very happy to have the phone telling me where I was along with map and compass out. A few years ago I wrote the following: "Never underestimate the winter mountains, but don't underestimate yourself either. I've seen terrifying avalanche debris in the Lakes, and a skier got avalanched in Wales last winter – fortunately without serious injuries, they do happen so know how to avoid them. My navigation is pretty good but confirming my pacing and bearings with the blue GPS spot and OS mapping on my phone is great and helps me operate in poor weather. Modern belay jackets and bothy bags, along with phones, also make it easier to both look after ourselves and look out for others in the hills." https://www.ukclimbing.com/articles/features/chasing_the_very_bloody_ephemeral_scottish_winter_climbing-11510

But sometimes I do wonder if those who complain about people not trusting GPS technology alone have ever actually tried navigating off Ben Nevis, in the dark, in the snow on a cold and windy February evening.

 GrahamD 23 Dec 2021
In reply to TobyA:

Well yes.  And it packed up.  See upthread for the fuller story.

In reply to TobyA:

> If your map blows away your phone is a lot better than nothing, and vice versa

this ^

In reply to UKC/UKH Articles:

Although not on top of The Ben… late afternoon of 4th Dec, I was on top of Scafell Pike in a pretty horrendous storm. Goggles snowed/fogged up in the blizzard, reduced to dropping to hands and knees regularly in the wind.. and getting dark. I had come over the tops from Langdale and Pike O Blisco, heading to Wasdale.  

I honestly believe that my Garmin GPSMap 66S with full 1:25 OS mapping got me out of the shit that afternoon…. But it was helped by the map and compass!
I always carry and do use a map and compass. I also have spare batteries for my GPSmap.   

I will admit that I learnt a lot that day (after having it for nearly a year). Keeping it inside the chest pocket not only keeps it warm… but avoids the buttons getting iced up, which then meant that controls were doing strange things!!(Not good)..

Consequently, I could not get the buttons to work until they all defrosted. The buttons can be used with big gloves, but the fact that ice had frozen up around the edges, meant that the buttons were useless.

You can see from my track that I was wandering rather blindly until I got the map and compass out and realised I was travelling South! My sharp turn North after summiting was because I used the map and compass. The buttons came back, after being warmed up inside my jacket at the turn West (Under the S of Cairns).

Used together, and understanding the issues of all equipment is the key I think.
 


 Harry Jarvis 23 Dec 2021
In reply to TobyA:

> Of course, and so are different phones and standalone GPS units - they are also all considerably more expensive than a map and compass.

Of course, if I were only using a phone for such a purpose, the expense would be an issue. But since my phone is suitable for a multitude of tasks, the relative cost is minimal.

> Have you navigated off the top of the Ben (or similar dog-leg necessitated terrain) in poor weather in winter with the set up you are using now? Does your phone and the app give you a directional arrow to walk on? And in such conditions are you happy to not take a map and compass with you?

Not on Ben Nevis. I have navigated off the top of Ben Nevis with a map and compass. Having been a hillwalker for over 50 years, I started navigating using map and compass and have been quite happy to do so. As I've grown older, I've lost the will to expose myself to the harsh conditions encountered at the top of Ben Nevis in winter - this coincides with the time where I've preferred to use a GPS unit, so although I haven't used a GPS in a whiteout on Ben Nevis, I have used one on numerous other Scottish hills in bad conditions and have never been left wanting. The GPS units and phone that I've used give  a real-time position, enabling one to see precisely the direction in which one is heading. It really is as simple as following a dot on a screen. 

I would always carry a map and compass. Quite often, I will carry a full OS map and a printout of the section I need - the printout lives in a small plastic wallet for ease of reference. 

Having extensive experience of both, my preference is very definitely for the GPS. That is not to say I eschew the use of maps. I love poring over maps, revisiting past adventures and imaging new ones - at my age, most of these are likely to stay in my imagination. 

 Rich W Parker 23 Dec 2021
In reply to UKC/UKH Articles:

Lots of chat here on the finer points of navigation so I'll add a couple of things.

Using any map and compass techniques we are never going to be 100% accurate, so nav in tricky conditions is a bit like being a detective; we gather pieces of evidence in order to build a picture, which is why it's not a great idea to rely on just one technique, for example pacing. But what if it's a complete whiteout and there's literally nothing too see? Well, there's timing, so in addition to my 94 paces to cover 150m I can estimate that at 3km per hour I'll be there in 3 minutes. Also having studied the map I can expect a very slight decent, even if it's invisible you can feel it under your legs. If things are really spooky you can use a few coils of rope to throw out in front of which will show you the what the ground is doing, that's good if you're worried about walking over a drift or an edge.

Breaking a journey down in to really short legs, linking identifiable features will mean that any error is far less compounded. Short legs also mean I really don't need to worry about magnetic declination, If I was nav'ing 1000m on the Cairngorm plateau then yes.

 Darkinbad 23 Dec 2021
In reply to featuresforfeet:

> If your map blows away your phone is a lot better than nothing, and vice versa

> this ^

I had this very experience in a white-out on Helvellyn, back in the days before GPS and mobile phones. Our only recourse was to follow our steps back down the route we had climbed. The importance of a decent map case should not be understated.

But more generally, I think mountaineering will go the way of yachting, where navigation using bearings and dead reckoning is still an essential skill but for most practical purposes a GPS-enabled device will be the primary (and reliable) tool of choice.

Post edited at 12:47
 GrahamD 23 Dec 2021
In reply to Darkinbad:

The issue with carrying the map as backup is that, if the GPS does pack in, you actually have to know where you are. The converse isn't the same.

1
 jpicksley 23 Dec 2021
In reply to GrahamD:

I'm glad that has been pointed out. A good reason to use m&c as your primary tools is to learn/maintain the skills for this very reason. Going m&c to gps is easy, going the other not necessarily so.

 HardenClimber 23 Dec 2021
In reply to TobyA:

In really shitty conditions locating your self with a GPS and then using a traditional compass while moving works well for me. When it is like that mag variation etc has always been irrelevant. As noted above it is useful to decide which direction is the better way to fail.

As for footprints / other people.... A few years ago coming off the Ben with some friends chatting and not taking that much notice of where we were going, we realised we were starting to drift into Five Finger Gully. We paused to check what we were doing, and on looking back whence we had come there was a line of people following us...

In reply to Spready:

Many years ago, I did a complete little circuit at the top of Pen Yr Ole Wen in a white out, still got no idea what actually happened but was a bit surprised when I realised that I was re-visiting the summit. Maybe it started with a 180 deg error and then not walking straight.

I then proceeded rather more carefully and correctly along the ridge until I was sure I could drop down the slope to Gerlan.

 Howard J 23 Dec 2021
In reply to UKC/UKH Articles:

I dare say those ancient navigators who relied on the colour of moss or the taste of seawater to find their way grumbled about these new-fangled lodestones.

 Fiona Reid 23 Dec 2021
In reply to Rich W Parker:

I tend to use a mix of map/ compass and memory map/ GPS on my phone these days.  Phone battery life is way way better compared with few years back and as both myself and partner have phones with the maps installed (locally,  no data connection needed) we'd be unlucky to have both devices fail.  

We both know how to use a map and compass and when it's really crap tend to revert back to pacing/ following a bearing with occasional checking of the phone to make sure all looks good.  Personally I find trying to follow the phone in crap weather or rough terrain harder than with a compass.  With the compass you pick your point and walk towards it. With the phone the pointer/direction arrow tends to be a bit jumpy and I find it much harder to follow accurately. 

I've navigated us within a few metres of Cairngorm Munro top navigating by compass only in white out conditions - pretty proud of that. I was quite surprised to get so close given that at times I was going from white icy blob to blob but satisfying too. 

I'll tend to use the technique that's most appropriate at the time.  Sometimes that will be taking a quick bearing to make sure the direction is correct and then handrailing a feature, other times micro navigation from point to point, other times it's just a quick check of the phone to confirm we're going the right way.  

Post edited at 14:59
 HardenClimber 23 Dec 2021
In reply to Howard J: Don't talk to me about lodestones....


 bowls 23 Dec 2021
In reply to tom_in_edinburgh:

I agree with this, but other that the dog leg past Gardyloo Gully which you can over compensate if you are worried then you have a degree of margin to get off the plateau and on most occasions as you descend within +/- 5° or maybe more onto the zig zags you will more or less be ok.  It may not sound particularly accurate (and maybe it isn't), but if you are in horrific weather on the plateau, are you really going to be getting  a rope out to measure etc/take back bearings or are you going to make the best judgement with the compass knowing you are probably not totally on the money, but still have enough bandwidth either way to stay out of trouble (either from 5 finger or from the North Face)?

For the record, have navigated of the plateau in a white out a few times, never used GPS...

Post edited at 17:47
 Martin Hore 24 Dec 2021
In reply to UKC/UKH Articles:

Interesting thread.  A number of people have said that they now navigate almost exclusively with GPS but carry paper map and compass as a back-up if (when) their GPS device fails. But IMO accurate map and compass navigation doesn't just require possessing a map and compass. It also requires the ability to use them and this comes from regular practice.

I used to regard myself as pretty good at map and compass navigation. I've needed to use it less frequently in recent years (because I go out less frequently in poor weather - not because I use GPS instead). With less frequent practice, I certainly find I'm not as accurate as I once was. I wonder how good at map and compass navigation your average hill-goer now is, if they've been relying almost exclusively on GPS since GPS came on the scene. 

One poster has been quite critical of those who don't take advantage of GPS technology while at the same time being rather disparaging about the accuracy that can be achieved with traditional map, compass and pacing. Possibly in his case the two are linked?

Martin

 jpicksley 24 Dec 2021
In reply to Martin Hore:

I see you have an interest in orienteering, Martin. My Dad was involved in the early mountain marathons in this country. He told once how he and his partner found a particular checkpoint. One had the bearing and the other had the pacing in thick cloud. They had their heads down concentrating and basically walking into the tent. Good orienteers are proof that pacing and bearing accuracy can be far greater than some people appear to believe.

 Howard J 24 Dec 2021
In reply to UKC/UKH Articles:

My navigation with map and compass is usually good enough to get me where I want to go (and hopefully back again!), but I wouldn't be confident I could get to a specific spot with the degree of accuracy apparently required for ML.  However most of the time it is only necessary to hit a large feature such as a stream. Perhaps I'm being complacent, or maybe I've just been lucky, but I don't think I've ever been properly lost, although I've occasionally been geographically embarrassed.  I admit to being lazy when it comes to practicing navigation, it isn't something I enjoy doing, so I'd say my skills are adequate but not expert. So far I've got away with it.

Having a GPS removes any uncertainty and gives me confidence that I know exactly where I am and where I'm going. Of course, like a car satnav I don't follow it blindly, I'm always aware of the terrain and other factors, and regularly refer to a larger map as well as the one on the screen.

In reply to jpicksley:

Transfer that to the Ben Plateau  ( other  hills and moorlands are available and more complicated ) and   assume you did not locate on first attack, answer relocate attack again    Relocating the summit of Ben Nevis not now a easy task as your no longer sure where you’re starting from  no hand rail and you don’t need to be  collected by the great collecting feature of the North face   This year I was shown OS  locate  your grid ref on demand ( with the usual flat battery caveats ) just to tempting no to switch on  even works in flight mode 

However one thing is as yet missing from this  discussion, is fear and how it plays out in, as has been said  in stressful situations. as well as torch light    

 Martin Hore 24 Dec 2021
In reply to jpicksley:

> I see you have an interest in orienteering, Martin.

Yes, that's right. Slightly different navigation skills required, but lots of cross-over with mountain navigation. I run less now, but spend a lot of time mapping. I find GPS useful for orienteering mapping, but my GPS can't be relied upon to give better than around 10m accuracy - that's not really accurate enough as the sole source of information for mapping at scales of 1:10,000 or larger. Fortunately we have LiDAR which, for what it shows, contours especially, is very accurate, as well as geo-referenced aerial photos. For features that LiDAR and aerial photography don't reveal, I find compass and pacing from known "attack points"  though time consuming, is more accurate than GPS. 

I've also navigated off Ben Nevis in white out conditions, before GPS was invented....... Somebody up-thread was complaining that one of the available large scale maps of Ben Nevis summit was sub-standard because it didn't "show" Five Finger Gully and Red Burn. The map they were referring to showed both quite clearly with contour lines. Unless I'm misinterpreting, their complaint was just that it didn't have printed names by the features .......

Martin

 jpicksley 24 Dec 2021
In reply to Name Changed 34:

Both good points. My answer to both is practice. The more you practice, particularly under stress, the better you get. That's exactly why m&c are my primary tools and I use them whatever the weather and visibility. For years I thumbed the map even on clear days. A bit harder now as I'm using poles more and my reading sight is getting worse so I'm having to adapt, which again is best done by practice.

PS for clarity, I'm not telling anyone what they should or shouldn't do. I completely understand that some people aren't as a anally retentive as I am about navigation (and I specifically mean using map and compass and not a gps). I got involved in this thread partly due to comments on the practical accuracy (or inaccuracy) with a map and compass and that we should use a gps as our primary tool, which clearly I disagree with.

Post edited at 17:01
 Howard J 24 Dec 2021
In reply to jpicksley:

I for one have never questioned that map and compass can be highly accurate.  However it is difficult to achieve and maintain that level of skill, and most of the time I find that level of accuracy isn't needed. Martin Hore complains that his GPS won't give better than 10m accuracy, but for most mountaineering purposes that is more than sufficient.

You appear to enjoy the technical aspects of navigation for their own sake, whereas I find them a chore. I don't enjoy crossword puzzles either, and sometimes navigating can feel like doing a crossword puzzle or a sudoku while standing in a cold shower.  I can do it if I have to, but a GPS makes it easy and more enjoyable.  I am also able to move more quickly because I don't have to worry about nav, which itself is often safer.

But what if stops working? they ask.  Of course tech can go wrong. but I've been using GPS for probably 20 years and it's never let me down yet. The only problems have been battery issues, which are entirely avoidable, and I always carry spares.  I'm now on my third unit, not because the others have broken down but simply because newer models are more sophisticated and now have OS maps. If it were to brick on me I would still have an accurate idea of where I was the last time I looked at it (probably only a few minutes ago if I were relying on it to navigate) and would be able to relate that to the paper map.  

 jpicksley 24 Dec 2021
In reply to Howard J:

Fair enough. Each to their own, as they say. I am absolutely interested by the technical aspects and continual improvement. I love it. Adds a lot to a mountain day for me. But we're not all the same. The debate was originally mainly around accuracy of using an m&c, and that's where I took issue. We're in a highly subjective area as are a lot of mountaineering subjects and opinion is clearly divided. My guess is that everyone contributing to this thread is pretty safe out there in this context and typically will have enough skill to get off the hill in one piece. We just do it differently.

I do actually carry a gps as well, for backup and inreach. It's not my go to for actual navigation (I could argue that one doesn't actually navigate with a gps, one follows it, but that's another rabbit hole) as j don't actually like using it for that. Yes, I have tried it.  I just find it boring and too small a screen.

 Howard J 24 Dec 2021
In reply to Martin Hore:

> Somebody up-thread was complaining that one of the available large scale maps of Ben Nevis summit was sub-standard because it didn't "show" Five Finger Gully and Red Burn. The map they were referring to showed both quite clearly with contour lines. Unless I'm misinterpreting, their complaint was just that it didn't have printed names by the features .......

That doesn't sound unreasonable to me.  Everything you read about the Ben says to avoid Five Finger Gully, but if you don't know where that is how can know where to avoid?  Yes, the contours show a gully but don't indicate just how dangerous it is.  Most accidents there occur because it appears to offer a way down (on the ground as well on on the map) and lures people in.  Similarly Red Burn is frequently referred to but may not be named on maps.  

The article which started this thread mentions both, but neither of the maps accompanying it show the names.  How are people expected to know where these are if they are not on the map?  In this particular article there is probably sufficient information to work it out from the text, but often this is not clear.

This is not necessarily the fault of the map makers, who may not be aware of climbers' names for features or appreciate their significance.  However guide book authors and writers of articles such as these should be more aware that their familiar names may not be known to their readers.

 Martin Hore 24 Dec 2021
In reply to Howard J:

> Martin Hore complains that his GPS won't give better than 10m accuracy, but for most mountaineering purposes that is more than sufficient.

I don't think I was complaining - just saying that 10m isn't really accurate enough for orienteering mapping - a pretty specialist activity. I agree, it's quite accurate enough for mountain navigation, as long as your GPS device keeps working. I'll not enter the argument about how likely it is that the GPS will fail as I don't have a lot of experience using GPS in the hills. I'm one of those who finds map and compass navigation highly satisfying and an integral part of a day on the hills. That doesn't apply to everyone I willingly accept.

Martin

 Martin Hore 24 Dec 2021
In reply to Howard J:

> That doesn't sound unreasonable to me.  Everything you read about the Ben says to avoid Five Finger Gully, but if you don't know where that is how can know where to avoid?  Yes, the contours show a gully but don't indicate just how dangerous it is.  Most accidents there occur because it appears to offer a way down (on the ground as well on on the map) and lures people in. 

I don't think I agree. The Harvey Superwalker map which is linked in the earlier post shows the top of Five Finger Gully very clearly as steep ground ringed with cliffs. On the map. it's not obviously less steep and less dangerous than the N Face itself. If you need a name against it to tell you it's potentially hazardous then what will you do if you're somewhere other than Ben Nevis confronted with terrain depicted similarly on the map without a name, or with a Gaelic name that means nothing to you - a pretty common occurrence. 

I'm not for a moment suggesting that getting off the Ben in poor visibility is easy. A slightly wrong bearing will take you near to the top of Five Finger Gully. I'm just not sure having it named on the map adds much additional information. If your navigation is poor enough (and I appreciate that in poor visibility and snow cover, it doesn't have to be that poor) to carry on down into Five Finger Gully without appreciating you've made a mistake, then you're probably not going to recognise where you are on the map, even if the gully is named. I expect most people who head down into the gully believe they're still on, or close to, the line of the tourist path and nowhere near Five Finger Gully, named or not.

Martin

1
In reply to Martin Hore:

> One poster has been quite critical of those who don't take advantage of GPS technology while at the same time being rather disparaging about the accuracy that can be achieved with traditional map, compass and pacing. Possibly in his case the two are linked?

I'm not an ML, I don't go on Ben Nevis in winter.  I'm an engineer and measurements are important to me.  I hear a lot of anecdotes of past successes but, I don't see any hard experimental evidence for the accuracy of pacing or walking on a bearing in the conditions we are talking about.

It seems highly unlikely that anyone can keep very close tolerance on the length of each step while walking across a boulder field or wading through deep snow in a high wind.  On flat smooth ground in reasonable weather I am sure that people who practiced could do so.   They could get reasonable accuracy on distance with two people and a measured length of rope - although the advertised length of a climbing rope could be several metres shorter than the actual length.

Similarly with compass bearings.   I've put a navigational compass on my desk and moved my cellphone near it.  It moves the needle - not surprisingly because there are some fairly strong magnets in the phone.  Anyone who is carrying a phone in their jacket when using a compass is not measuring north accurately to a degree.  One degree is 0.28% of the full circle.  Equally, if you are taking a bearing it is simple trigonometry to show that at 20 metres if someone's head is 15cm across you would get a 0.4 degree difference depending on whether you aimed at the left or right of their face.  So in a whiteout when you can't see very far  your angle measurements are not going to be that accurate and the angle error is going to accumulate if you do many legs.

Finally, when it comes to previous experiences of GPS.  GPS, especially as implemented in cellphones is an evolving technology.  You can't assume that things it was not able to do a few years ago it can't do today.  With a modern phone it won't just be using the GPS satellites, it will also be getting assistance from the cellphone base station and supplementing with dead reckoning using a built in electronic compass and accelerometer to get an estimate of your position.

In reply to tom_in_edinburgh:

Angle error get corrected as you move through terrain and features. It's extremely rare that the only navigational information you are using is a compass bearing. 

All your information about accuracy is correct, however it just isn't how people navigate in the real world.

Evidence of success- people not falling down said gullies pre GPS.

Post edited at 10:10
In reply to Alex Riley:

> Angle error get corrected as you move through terrain and features. It's extremely rare that the only navigational information you are using is a compass bearing. 

> All your information about accuracy is correct, however it just isn't how people navigate in the real world.

> Evidence of success- people not falling down said gullies pre GPS.

I'm not arguing people can't navigate successfully with map and compass. I'm arguing against giving bearings like 231 degrees which implies higher precision than is realistic.

Post edited at 11:15
In reply to tom_in_edinburgh:

What are you suggesting, round it to the nearest hundred

1
 jpicksley 25 Dec 2021
In reply to tom_in_edinburgh:

You said: I hear a lot of anecdotes of past successes but, I don't see any hard experimental evidence for the accuracy of pacing or walking on a bearing in the conditions we are talking about.

That's a fair comment and I've been guilty of it in this thread. Prior to this thread I've just started to actually try to measure my actual accuracy in order to improve it. I'm fairly new to the GPS scene and it finally dawned on me I can measure a leg in Basecamp after the event, so i've just done that.

I did a leg from the 1140 contour line (confirmed by GPS at the time as I'm in practice mode) directly to a point in between the cairn and the weather station. I measured 400mts and took the bearing. After I'd paced what I though was 25 doubles short of 400mts I was directly on a line between the cairn and the weather station. I've since checked the leg in Basecamp. Clearly I walked the bearing correctly (I'll admit to being closer the weather station than the cairn). The distance between the cairn and the weather station is about 20/25mts and I aimed to split that distance, so I must have had an error on the bearing of less than 10 mts. I haven't worked that error out in % terms yet. I measured what I paced to be 373 mts. 25 doubles for me (65 to 100mts) is approx. 22mts. So I paced 378mts as compared to an actual distance of 373 mts. There's a 200mts stretch of that leg at around 20% and it's very bouldery. The whole leg is very bouldery. The weather was good but it was dark and I was on a headtorch. That's around about a 1% error over terrain that your saying it's impossible to be that accurate on. That's not an unusual level of accuracy for me.

Another example that night was a bearing I followed. 900 mts from the tor east of Cairngorm top to the Ptarmigan. I didn't pace but just followed the bearing. The terrain is mostly a descending traverse line over boulders (and presently some snow). I couldn't see the Ptarmigan until I was about 200 mts away at which point it was clear that if I followed the bearing through I would walk through the front door.

The evidence of the legs is my GPS track and my word on what I did during each leg but I realise that's a very small sample size and you may choose not to take my word for it. I'm not sure what else one can do to prove accuracy though. It's quite a difficult thing to do. Any suggestions you have would be welcome.

I intend on doing more of this though, purely for my own improvement and enjoyment. I'll report back to you.

1
 Martin Hore 25 Dec 2021
In reply to tom_in_edinburgh:

> I'm not arguing people can't navigate successfully with map and compass. I'm arguing against giving bearings like 231 degrees which implies higher precision than is realistic.

No matter how accurately you can follow a bearing, if the correct bearing is 231 degrees you'll be more accurate, on average, if you set your compass to 231 degrees rather than to 230, 232 or 235. So you might as well do it. Once it's set, you don't need to refer to the actual number again (except for an occasional check that your compass dial hasn't rotated by accident - most are stiff enough not to). Silva type compasses normally have marked intervals at even numbered degrees, but it's easy enough to set to odd numbers just by setting between two marks.

As others have mentioned, compass bearing errors tend to cancel out over a longish leg. You will learn from experience whether you have a consistent tendency to veer to the left or right, or, more commonly, to veer downslope or downwind, and make appropriate compensations. The terrain will also give you useful clues, even in a whiteout, particularly the slope angle and direction.  

I'm a bit worried, Tom, how much bad weather navigation experience you actually have. Your profile, which I accept of course may be well out of date, suggests that most of your mountaneering experience is at Ratho. Several of the people taking a different point of view in this thread clearly have a lot more experience both than me, and perhaps than you. You're right, I think, to point out that GPS has given us an extra, quite powerful, tool in our bad weather navigation armoury, but wrong I think to suggest that the more traditional methods cannot be employed accurately. But they do need to be practiced if they are to be of value if, or when, your GPS device fails.

But enough of that. Time, now, to enjoy my Christmas meal!

Martin

 jpicksley 25 Dec 2021
In reply to jpicksley:

I made an error in my reply - I meant 15 double paces, not 25. Silly me Happy Christmas All.

 Fiona Reid 25 Dec 2021
In reply to jpicksley:

> I intend on doing more of this though, purely for my own improvement and enjoyment. I'll report back to you.

You and the others commenting on this thread have inspired me to do some experiments 😀. Thank you for that everyone.

I passed my summer ML in 2013 so am reasonably happy with my ability to navigate.  

I think some experiments with the map and compass whilst recording a track so I can see how close I get to where I'm meant to be are in order. 

Post edited at 15:00
 jpicksley 25 Dec 2021
In reply to Fiona Reid:

Excellent! Good luck and enjoy.

In reply to Alex Riley:

> What are you suggesting, round it to the nearest hundred

Round it to the nearest 5 degrees.

11
In reply to tom_in_edinburgh:

I'd be aiming between SW and WSW and checking every 100 paces or so to make sure I'm still on that approximate bearing. That gives a precision of 32 choices of direction which has been enough for me so far. From reading this thread it sounds like much better precision than that is achievable but I don't think I could even read the map with any more precision than that in bad conditions.

 Smelly Fox 26 Dec 2021
In reply to tom_in_edinburgh:

I hear a lot of what you’re saying. I too am an engineer, and it pisses me off no end when clients demand an order of magnitude greater accuracy when it’s simply not achievable with the measuring devices available.

However, I can easily see the difference between of a degree on my silva compass. Therefore the information needed to take a bearing given to the nearest degree is acceptable, and gives the best possible data for the starting point. The accuracy or skill of what you do after taking the bearing isn’t really relevant, only the measurement.

Whether or not the compass is in calibration is another matter… but should not affect the correct data being given to start off with.

In reply to Smelly Fox:

> However, I can easily see the difference between of a degree on my silva compass. Therefore the information needed to take a bearing given to the nearest degree is acceptable, and gives the best possible data for the starting point. The accuracy or skill of what you do after taking the bearing isn’t really relevant, only the measurement.

I completely agree that on a clear day with a distant object you can take a bearing accurate to 1 degree.  On the other hand, on a clear day where you can see distant objects you don't need to take bearings at all.

In a whiteout or thick cloud in bad weather on top of Ben Nevis I doubt it.  As I pointed out above if you can see 20m then 0.4 degree would be the difference between points 15cm apart.  That's not much more than the width of someone's face.  Are you going to stand there on top of a mountain shouting at your friend to stand absolutely still and move a centimetre to the left or right until you get their nose lined up exactly on 231 degrees.

In reply to tom_in_edinburgh:

No, because you don't need to, as has been said over and over that isn't how navigation works in the real world. The compass bearing is only one tool/factor and leapfrogging like you are describing is only one method of walking on a bearing (and often not the best option in winter, where edges are often corniced or hidden).

 Smelly Fox 26 Dec 2021
In reply to tom_in_edinburgh:

I refer you back to where I stated that only the measurement matters, what you do with that measurement is irrelevant. 
 

The article states, stand on point x (summit cairn) and take a bearing 251deg. It doesn’t matter what the visibility is, so long as you can see the compass, you can do exactly that.

What you do with that 251deg measurement is up to you, but at least you are working with the best possible data, which you instrument should be perfectly capable of using.

Anyway, this thread is going round in circles! I’m out. Have fun out there!

2
In reply to Smelly Fox:

> I refer you back to where I stated that only the measurement matters, what you do with that measurement is irrelevant. 

If you were making a model airplane with paper and scissors and the instructions said to cut at 10.3521cm that might be the optimal point as determined using trig by the person designing the plane but it is a stupid instruction to give someone working with a ruler and a pair of scissors.  It would be more sensible to say 10.4cm, it wouldn't make any difference to the end result and it would let the person carrying out the instructions know they were actually doing OK if they kept the cut roughly straight at 10.4cm.

4
In reply to tom_in_edinburgh:

But in this case we have a device that can resolve to 1 degree comfortably ( standard baseplate compass) vs a ruler at 1mm ( my ruler) so in your example 10.4cm is the same as 231 degrees (or whatever).

if people said follow a bearing of 231.27 you would have a fair point.

1
In reply to tom_in_edinburgh:

That analogy is irrelevant because compass' are measured to the nearest degree and it isn't hard to set it as such. 

I'm also out on this one.

 Catriona 26 Dec 2021
In reply to tom_in_edinburgh:

One of the most common ways to get a bearing is to take it from a map. I assume you’ve done this? Using my Silva compass gives a grid bearing to within two degrees, which I can then adjust for magnetic variation if I can be arsed. Should I then turn the compass bezel to the nearest five degrees mark to follow that bearing? I don’t think so. Should I round the bearing to tell someone else the bearing we’re following?

Maybe this is the source of compass bearings frequently being given to a level of precision which you view as unacceptable?

You’re an engineer? Good Engineering includes an element of understanding how something will be used in real life by real people.

1
In reply to Catriona:

> Maybe this is the source of compass bearings frequently being given to a level of precision which you view as unacceptable?

I don't think it is unacceptable, I think it is unhelpful and misleading when giving instructions to quote measurements which imply an expectation of more precision in the activity than is realistic / possible.

Of course there's no point in turning the dial to the nearest 5 degrees after you've taken a bearing for yourself but that's not the situation.  The situation is providing instructions for a large number of people to follow.

1
In reply to Smelly Fox:

> Anyway, this thread is going round in circles! 

You see, what you need is a compass to avoid that... 😉

In reply to tom_in_edinburgh:

What about telephone numbers? They're quite complicated to remember... Maybe we should round them to the nearest 10. Just think how much easier phone numbers would be to remember if they all ended 0?

1
In reply to tom_in_edinburgh:

> I don't think it is unacceptable, I think it is unhelpful and misleading when giving instructions to quote measurements which imply an expectation of more precision in the activity than is realistic / possible.

But it’s perfectly possible to set a compass at the level of individual degrees - so what’s your beef?

In reply to TobyA:

If you have a compass and a phone you can go round and round!

In reply to TobyA:

> Just think how much easier phone numbers would be to remember if they all ended 0? 

Nah. Make them all begin with zero...

In reply to Dr.S at work:

> so what’s your beef?

Setting a compass to a bearing is one thing; following that bearing in difficult terrain, poor visibility and strong winds is another thing entirely.

On easy terrain (a nice path), I can pace to an accuracy of about 1%; I've measured it many times. I can also walk in a straight line over hundreds of metres; also tested many times. That's just walking, having chosen a direction, without looking at a landmark whilst walking. I've even tested it walking across a playing field with my eyes closed.

In 'the wild', it's a different story.

1
In reply to Alex Riley:

> That analogy is irrelevant because compass' are measured to the nearest degree and it isn't hard to set it as such. 

Like you, I'm baffled. If you have an instrument where bearing can be set to the nearest degree, why not give the actual bearing?

Yes, the operator might set it incorrectly, may not be able to keep on that bearing due to visibility, might have a compass that isn't quite calibrated correctly (could be + a degree or so, could be  minus), might have a phone somewhere about their person. These are unknowable factors, so what is the point of giving anything other than, (assuming perfect conditions and equipment), the 'correct' bearing? You're just introducing a potentially greater error in navigation than by giving the correct bearing.

In reply to captain paranoia:

Of course you will make errors - but you may as well start off with the correct target data.

id prefer to be +/-n from the ideal reading than +/-n from one already a few degrees off ideal.

In reply to Dr.S at work:

> But it’s perfectly possible to set a compass at the level of individual degrees - so what’s your beef?

You know, if you look at most compasses, the scale is marked at 2 degree intervals.  Just saying.

https://silvasweden.uk/collections/outdoor-compass/products/expedition-4

10
In reply to tom_in_edinburgh:

Yep - and I’ve always been taught that it’s reasonable to measure to half of the marked increments on a scale. 

1
In reply to tom_in_edinburgh:

> the scale is marked at 2 degree intervals.

My Quechua Geonaute compass is marked with 1 degree scale. But I have always managed to interpolate between the markings on my 2 degree Silvas.

I have also devised a vernier system for more accurately aligning the needle to N, inspired by my vernier romer that allows those 8-figure GRs to be read.

Post edited at 20:01
In reply to Dr.S at work:

> Of course you will make errors - but you may as well start off with the correct target data.

I'm not arguing that at all. But the reality is that following bearings and pacings over any distance is taxing in difficult conditions.

That's why I teach DofE participants that features allow us to snap ourselves back to known positions; direction & distance are means to get roughly to features.

Features are hard to find in poor visibility. So you pick prominent ones, even if that isn't as direct a route.

In reply to captain paranoia:

Of course - but Tom has been arguing for not selecting the correct bearing in the first place.

more generally it would be quite interesting to study the accuracy of map and compass users - I’ve had a quick look but not turned up any references. 
 

I expect many of us have had experiences of long nav legs in difficult conditions resulting in being bang on the money- and also rather more chastening episodes! Knowing the reasonable bounds of performance in differing environments/conditions would be quite useful. And if we could identify factors that improve performance then that could be extremely useful. Perhaps a little UKC citizen science project ?

 summo 26 Dec 2021
In reply to Fiona Reid:

> I think some experiments with the map and compass whilst recording a track so I can see how close I get to where I'm meant to be are in order. 

For orienteering training with the kids, we do 200, 300, 400m... legs across flat ground at night, just aiming for controls we put out or single contour knolls. Apart from them seeing if they drift at the time, we look on strava / livelox afterwards. 

In reply to Dr.S at work:

> but Tom has been arguing for not selecting the correct bearing in the first place.

He's been saying quite a few things, but I thought his main point was about the difficulty in following accurate bearings, and that the consequences of likely process error bounds should be discussed. 

He also pointed out GPS is beneficial. This is what I would use; GPS to correct drift (providing 'virtual snap features'), and compass and pacing for microlegs in between. In extremis, I'll use all the tools at my disposal.

Having worked on pedestrian navigation with phone accelerometers (and better), he's rather optimistic about their ability to perform dead reckoning, though... 

 Smelly Fox 26 Dec 2021
In reply to tom_in_edinburgh:

Ok I’ll bite again haha.

You are arguing now for arguments sake brother! And you are wrong, but I don’t think you will get see why by reasonable counter argument. Or perhaps you are just trolling now, I’m not sure…

peace and love 

In reply to Dr.S at work:

> Of course - but Tom has been arguing for not selecting the correct bearing in the first place.

I've been arguing that you shouldn't kid yourself about how good the instruments and ability to walk on a bearing are by giving over-precise measurements.

It's like looking at a piece of lab equipment with a six figure display the bottom four figures of which are noise and putting all six figures in the report.   It makes the measurement look more precise than it is.

With the compass we have:

a. influence of magnetic items e.g. cellphones the user is likely to be carrying.

b. grid variance

c. trying to measure to one degree on a scale marked to two degrees in bad conditions.  We aren't talking about a nice sunny day - if it was a nice sunny day you could do it without a compass.

d. taking bearing to something fairly close to you where just the width of the thing you are taking the bearing to is going to span 0.4 degrees.

7
In reply to Smelly Fox:

> You are arguing now for arguments sake brother! And you are wrong, but I don’t think you will get see why by reasonable counter argument. Or perhaps you are just trolling now, I’m not sure…

The incredible thing is that in 2021 anyone would argue for using a map and  compass rather than a GPS as the primary navigation tool in a serious situation. 

I don't need to win the argument on an internet forum, I can just sit back and let market forces do their work.

2
In reply to tom_in_edinburgh:

I presume that people get in trouble up there when it's all white and some need to be rescued. It would be interesting (in the context of this discussion) to know how many were navigating with GPS and how many with map and compass.

 summo 27 Dec 2021
In reply to tom_in_edinburgh:

> I've been arguing that you shouldn't kid yourself about how good the instruments and ability to walk on a bearing are by giving over-precise measurements.

I'd be arguing don't under estimate how precisely you can walk on a bearing if it's a skill regularly practiced. And it is a skill learnt through experience, not just the setting the compass, but how you also position your arms, hands and body, how you walk and what you focus on. If you haven't got your axe or phone near it the compass doesn't lie (ignore bits of skye, bowfell...) and maps are drawn to incredible accuracy. M&C eats no meat, it'll always be there in your bag. 

> I don't need to win the argument on an internet forum, I can just sit back and let market forces do their work.

That doesn't mean a GPS is better than a map, that's marketing. All those who had their cars towed out of fords or got lorries stuck on tiny roads prove it annually.

1
In reply to summo:

> That doesn't mean a GPS is better than a map, that's marketing. All those who had their cars towed out of fords or got lorries stuck on tiny roads prove it annually.

Getting told where you are with high accuracy is inherently more useful than having to figure it out by dead reckoning.  That's not marketing, that's a qualitative difference in the technologies.

The actual question is how often do people get lost when using GPS compared with when they are trying to use a paper map.  And the answer is a lot less often.

1
In reply to tom_in_edinburgh:

https://www.outsideonline.com/outdoor-adventure/snow-sports/chamonix-zermatt-alps-haute-route-disaster/

Tldr: a combination of bad conditions, poor decision making and over reliance on gps technology results in multiple fatalities 

 stuartf 27 Dec 2021
In reply to tom_in_edinburgh:

Out of interest, how accurate do people think they can be when (1) lining up the grid lines on the compass bezel with the ones on the map when measuring a bearing, and (2) lining up the needle with the arrow on the bezel when orienting themselves in the correct direction? I doubt I can do either more accurately than a couple of degrees unless I've got the map spread out on a flat table and use the sighting feature on my Silva type 4 compass. I'd be interested for any tips people might have on how they do this in real world conditions.

 Howard J 27 Dec 2021
In reply to Alex Riley:

Tragic, but it reinforces what most people on this thread have been saying - don't rely on a mobile phone, and have back-up systems.

The eTrex which one of the party was carrying is a great little unit and not too expensive, as these things go, but is now old technology.  The latest units have full colour mapping and greater accuracy - at a price, of course.

 deepsoup 27 Dec 2021
In reply to tom_in_edinburgh:

> I've been arguing that you shouldn't kid yourself about how good the instruments and ability to walk on a bearing are by giving over-precise measurements.

The instrument in question, the bezel on a baseplate compass, can be set to within a precision of 1-2 degrees though. 

Whether you can follow that bearing precisely is a different thing - even if you can only manage plus or minus 5 degrees, if the desired bearing is 231° then surely it's better to walk on a bearing of 231±5° than 230±5°.

With a random deviation off course there's a probability 'bell curve' of what bearing you will end up actually having followed when you've walked a little way, sharper or flatter depending on how precise you are.  But even if the curve is flatter than you would ideally want it to be, since you can easily do so it just makes sense to put the peak of the curve where you want it to be doesn't it?

In reply to Alex Riley:

"Castiglioni was navigating with the help of his smartphone, a common practice among Alpine guides. “On a trip like this, I’d say most guides are carrying a small Garmin GPS as a backup, but they’re primarily using their smartphone, because it works very well for navigation these days with apps like Gaia,” said Remsberg, referring to the GPS-based mobile app that offers preprogrammed hiking and touring maps.

There is spotty cellphone coverage throughout most of the Haute Route, but reception isn’t necessary for the navigation apps to work, since they rely on GPS. Most guides, Remsberg said, actually switch their phones to airplane mode and turn off everything, except the navigation app if they need it, to save battery power. But the apps themselves use a lot of power, so most guides use a case with a built-in secondary battery and carry a larger backup battery that can recharge the phone several times. In addition, under normal circumstances, guides tend to take their phones out only periodically to check their group’s progress on a route and then put it away in a warm pocket, because cold temperatures degrade battery life."

It's hardly an advert for using paper maps and a compass.  What it says is professional Alpine guides are using cellphones for navigation.  That's a hell of an endorsement of the consumer technology, given that cellphones aren't designed for extended-temperature range applications like this.

The main problem these guys had was not turning back when things turned bad and not making sure the batteries in safety critical devices were fully charged.

 Howard J 27 Dec 2021
In reply to stuartf:

> I'd be interested for any tips people might have on how they do this in real world conditions.

A map case is essential, otherwise the map can be impossible to handle and could even blow away. Try to find some shelter, even if it's only from your companions' bodies.  It shouldn't then be too hard to align the compass with the map grid.  Setting the bearing has scope for error, especially if you're estimating between the degree markers, but the markers themselves are fairly wide and cannot be precise.  I find the biggest scope for inaccuracy is then trying to adjust for magnetic variation, although for now this can be ignored in the UK. 

Of course errors creep in, which is why it's surely important to to strive to be as accurate as reasonably possible when setting the original bearing.  However in most situations it's good enough.  Unless you're orienteering or on a nav exercise it's not usually necessary to achieve pinpoint accuracy.

Even on the Ben, at its narrowest there's still probably 100m between the North Face on one side and Five Finger Gully on the other.  The first leg is probably crucial to get to the correct turning point to avoid Observatory Gully, but over 150m any reasonable inaccuracies in the bearing or estimating the distance should still get you to roughly the right place to make the turn, at least within acceptable tolerances.  Once you're on the 282 degree bearing, even with unavoidable errors you're probably going to hit that window without too much difficulty.  This is not to say that you can be sloppy, just that the inevitable inaccuracies even when taking reasonable care are probably not going to make a crucial difference. What is important is to know where the hazards may be and to remain aware of the terrain.  You shouldn't just be simply following the heading on the compass or GPS, you have to use other information as well.

The advantage of GPS is that it will tell you where you really are, rather than where you think you are.

In reply to tom_in_edinburgh:

It's not really an endorsement, most of them died.

2
 summo 27 Dec 2021
In reply to stuartf:

> Out of interest, how accurate do people think they can be when (1) lining up the grid lines on the compass bezel with the ones on the map when measuring a bearing, and (2) lining up the needle with the arrow on the bezel when orienting themselves in the correct direction? I doubt I can do either more accurately than a couple of degrees unless I've got the map spread out on a flat table and use the sighting feature on my Silva type 4 compass. I'd be interested for any tips people might have on how they do this in real world conditions.

The reality is you don't need to be more accurate than that, you can safely get off any Scottish summit in a white out, a night, using just M&c and pacing. You'll be able to say at any time I am here to a high enough degree of accuracy that you will feel satisfied you are where you think you are.

In reply to stuartf:

I'd be interested for any tips people might have on how they do this in real world conditions.

When tackling from the map do NOT aline the compass edge use the scale lines within the back plate from  point to point   

 summo 27 Dec 2021
In reply to Howard J:

>   I find the biggest scope for inaccuracy 

I find the biggest cause of error in either mountaineers or novice orienteers is the position of the hand & arm in relation to their body, and the direction they run. Many align perfectly on the map, but you have to make sure you go with the needle once on the ground too. It's hard explain online, but if your hand is out to the front and a little to the side of you, than you aren't looking down the line of the needle, but slightly across it. You'll swerve according to which hand it's in. The same with a bend in the wrist. 

Post edited at 11:59
 summo 27 Dec 2021
In reply to Name Changed 34:

> I'd be interested for any tips people might have on how they do this in real world conditions.

> When tackling from the map do NOT aline the compass edge use the scale lines within the back plate from  point to point   

For frequently frequented areas just laminated a small section of map. Or in the corner write down the bearings and you just need to set the compass and go. If it's truly mental on the summit and you can hear it howling, sort your map and compass out on the last stance before topping out, have it in a pocket ready, talk with your second about the plan while you can still hear each other. Stay roped up if you aren't confident, or use it to measure 50m and a very precise bearing. You can de-kit and chat when lower down out of the chaos. 

Post edited at 12:06
 Martin Hore 27 Dec 2021
In reply to Alex Riley:

> It's not really an endorsement, most of them died.

I've just read the whole article - a terrible tragedy. It's a complete mystery to me how Tom thinks this supports his argument. It seems clear that there were two main causes. Over-reliance on phone-based GPS technology which failed, and over-reliance on the guide (who was himself over-reliant on GPS technology which failed). The guide was 60 years old. If he was local, he would almost certainly have navigated this popular route many times by map and compass before GPS was invented. I've done it twice, 50 and 30 years ago, and I'm definitely not local and definitely not a guide. So I can only think that the guide was lulled into a false sense of security by the technology and was no longer bothering to carry a back-up system - ie a map and compass - tricky as it would have been to use even these once he had allowed the group to climb higher into ever-worsening conditions.

Tom started in this thread with a good point IMO. That is that given the ready availability of GPS today it's difficult to justify not carrying a GPS device on the hills, as an additional source of information, when there's a chance that accurate navigation will be needed. Having not owned a smartphone till very recently, I've only now converted to this view. If I was still to convert, Tom's earlier posts would have helped steer me in that direction. 

But the point Tom has been arguing all over Christmas, in the face of almost universal opposition from everyone else who's posted, is that map, compass and pacing cannot be relied upon for accurate (say sub 5 degree) navigation, so why bother to set your compass accurately in the first place. This has been comprehensively refuted, both on a mathematical basis - why needlessly introduce an additional error - and from the personal experience (rather greater than Tom's I suspect) of those who regularly achieve better map and compass accuracy in the hills. 

At best, internet forums can be a source of much useful information and opportunities for valuable learning (eg wintertree's weekly COVID plotting) but it's rather difficult to learn if all you do is stick doggedly to your original position in the face of such universal and well-informed contradiction.

Martin

In reply to Martin Hore:

Rounding to 5 D will not be more than 2.5.  (Out). 

 summo 27 Dec 2021
In reply to Name Changed 34:

> Rounding to 5 D will not be more than 2.5.  (Out). 

But it's counter productive, before taking a single step you've created an inaccuracy, if you drift on the ground in the same direction as your rounding, you are adding to it. It's not helping or beneficial in the slightest. Take the best bearing off the map you can, rest on your knee etc..  pace and time accurately, then you'll be safe every time. No battery issue, hard to read screen, you can share pacing and timing between you, so you have a double check too.

In reply to summo:

> But it's counter productive, before taking a single step you've created an inaccuracy, if you drift on the ground in the same direction as your rounding, you are adding to it. It's not helping or beneficial in the slightest. Take the best bearing off the map you can, rest on your knee etc..  pace and time accurately, then you'll be safe every time. No battery issue, hard to read screen, you can share pacing and timing between you, so you have a double check too.

All true    As is 5/2 = 2.5 

yes why round ???? Pointless I know and counter productive 

 Martin Hore 27 Dec 2021
In reply to Name Changed 34:

> Rounding to 5 D will not be more than 2.5.  (Out). 

That's true, though as Summo points out, it doesn't really affect the argument.

I thought I'd experiment. I've just taken the bearing between the same two points on an OS 1:25,000 map 5 times using two different Silva compasses - one new, one old with fading lines on the dial - and using a different edge or orienting line on the baseplate each time. Map in mapcase, but not in whiteout conditions of course. Results in degrees, read off the scale to the nearest one degree: 15, 14, 16. 15. 14. So if the average is nearest to the truth (not a given, of course) then my worst result is out by 1.2 degrees.

The idea that if you're told the bearing (rather than taking it from the map) it's simpler to set to the nearest 5 degrees is surely wrong. When the compass dial has 2 degree gradations, which most do, half the time, you'll still be setting it by splitting the difference between two gradations. You might as well set to the nearest degree and minimise errors at this stage.

But most of the time when out on the hill, or orienteering in the forest, I'm not bothered at all by the bearing in numbers, rounded or not. I just take a bearing off the map, and use it to sight ahead, or take the bearing of an object ahead, and lay it back on the map. The numerical bearing is irrelevant. I only look at it if I'm going to syncronise my compass with others in the party, and/or walk a long leg on the bearing so I can periodically check the dial hasn't moved.

Martin

In reply to Name Changed 34:

> All true    As is 5/2 = 2.5 

> yes why round ???? Pointless I know and counter productive 

It's a well established principle that you should not quote a measurement to more significant figures than the equipment you used to make it is capable of.   It's dishonest and unhelpful to do so because you give a false impression of the precision of the measurement.  Also when giving instructions it is unhelpful to give unnecessary precision because you are implying that you expect that precision when carrying them out.

For example if you tell someone to cut a bit of metal 0.0231cm rather than 0.023cm they are going to assume you want the cut precise to +/- half of the last significant figure in the measurement and they're potentially going to use fancier and more expensive equipment to achieve it.  Same if you tell someone to walk on a bearing of 231 degrees, that would imply that you expect +/- half a degree precision in following your instruction, when actually you expect far less precision.

The complicating factor when trying to apply normal rules about significant figures in measurements is that degrees aren't a decimal measurement. But the principle of not giving unnecessary precision still holds.

8
 deepsoup 27 Dec 2021
In reply to tom_in_edinburgh:

> It's a well established principle that you should not quote a measurement to more significant figures than the equipment you used to make it is capable of. 

All well and good, but a baseplate compass is capable of resolving down to single degrees.  Whether I can walk on a bearing of 231° is moot (personally I almost certainly can't), I can set that angle just as easily as I can any other odd number.  Using the bezel on my Type 4 Silva compass as a protractor I can quite easily distinguish between 44° and 45° say.

> The complicating factor when trying to apply normal rules about significant figures in measurements is that degrees aren't a decimal measurement.

How is that relevant, when nobody is talking about anything less than integer numbers?
For what it's worth I'm pretty sure it's just as common for lat/long coordinates to be quoted in 'decimal degrees' as it is to use minutes and seconds these days.  (Though on a marine chart it's obviously useful to have the latitude scale marked in minutes, because one arcminute of latitude = 1 nautical mile across the ground.)

Post edited at 15:36
In reply to deepsoup:

> How is that relevant, when nobody is talking about anything less than integer numbers?

Significant figures apply to integers just as much as decimal fractions.  231 is three significant figures.

Post edited at 15:44
 deepsoup 27 Dec 2021
In reply to tom_in_edinburgh:

Indeed, but whether fractions are decimal or not is irrelevant when you're talking only about integers; it hardly matters how you express fractions when there are no fractions.

Whatever.  It was my mistake adding that paragraph to my post thereby making it easy for you to reply to it while ignoring the other one.  My mistake replying at all, tbh, when you've already ignored the same point made by several others above.  The 'significant' part of my post was this bit
(rephrasing it slightly):

All well and good, but the bezel of a baseplate compass is capable of resolving down to a single degree.

Post edited at 16:01
1
In reply to UKC/UKH Articles:

For the obvious advantages of reliability, portability, minimalism and weight, and for the immense satisfaction I gain from (usually) being able to use them properly, I'll be sticking to map and compass.

GPS is a great tool, I agree, but it is just one tool. When it all hits the fan when your GPS packs in, if you don't regularly use a map and compass you're highly unlikely to immediately regain competence on the summit plateau in a white-out.

To the arguing over compass navigation accuracy, I'm with the majority. Yes it's not exactly accurate — so why on Earth would you introduce a further inaccuracy by rounding the correct bearing? If you try navigating on the correct bearing, you'll be more accurate than if you try to do so on a bearing that you've deliberately made several degrees out. That's plain and obvious.

 Martin Hore 27 Dec 2021
In reply to tom_in_edinburgh:

> It's a well established principle that you should not quote a measurement to more significant figures than the equipment you used to make it is capable of.   It's dishonest and unhelpful to do so because you give a false impression of the precision of the measurement.  Also when giving instructions it is unhelpful to give unnecessary precision because you are implying that you expect that precision when carrying them out.

OK. Please use your engineering expertise to explain why the following is wrong.

Example 1. I have a 5m builders' tape measure. I can measure to the nearest millimetre a length of 4321mm. That's 4 significant figures. But I can't measure a length 4.321mm - also 4 significant figures. The compass is the same. I can measure 231 degrees to the nearest degree - you do now accept that I hope - but I can't measure 2.31 degrees, and it would be wrong to claim that I could. So significant figures is the wrong concept here surely. It should be decimal places - which is realistically zero in each case - though I accept you could subdivide millimetres on a tape measure with care.

Point 2. We had builders in last year to build us an extension. The architect gave them measurements to the nearest millimetre.  They measured out all their distances to the nearest millimetre which they were readily able to do using tape measures or laser devices. They couldn't lay a course of brick-work to precise millimetre accuracy, but no issue there. They preferred to start from the best measurement they could to keep any resulting errors to a minimum. 

Martin

In reply to Martin Hore:

> The numerical bearing is irrelevant.

For normal map and compass navigation, yes.

But if you're following predetermined bearings, it isn't.

GRs and bearings are for communicating navigation information, to others, or to yourself.

In reply to tom_in_edinburgh:

> It's a well established principle that you should not quote a measurement to more significant figures than the equipment you used to make it is capable of. 

It is, but you can read and set a compass to at least as good a resolution of 1 degree. That's what you should do. Even if you can't follow that bearing accurately, it's what you should aim for.

You have talked about magnetic items disturbing the compass. You should know not to have magnetic items near your compass. It's one of the basic things I teach DofE participants.

 Maggot 27 Dec 2021
In reply to Martin Hore:

> (in reply to Scottish Tom) Please use your engineering expertise

😂😂😂😂😂😂😂😂

He HAS to be trolling?!?!

In reply to Martin Hore:

>  The compass is the same. I can measure 231 degrees to the nearest degree - you do now accept that I hope -

Well no, because you just posted a few hours ago an experiment where you tried to measure a bearing five times and you got 15, 14, 16. 15. 14.   Presumably that's in pretty optimal conditions in your house on a flat table.  If the correct answer is 14 then the error on your measurement of 16 is +2 degrees.  If the correct answer was 16 then the error on your 14 measurement was -2 degrees.  And you only took 5 measurements.  Maybe if you'd taken 10 there would be 13s or 17s as well.

Looks to me that if you give me a single reading with your baseplate compass I should assume it is +/- 2 degrees.

> but I can't measure 2.31 degrees, and it would be wrong to claim that I could. So significant figures is the wrong concept here surely. It should be decimal places - which is realistically zero in each case - though I accept you could subdivide millimetres on a tape measure with care.

No the concept is significant figures. Otherwise you could make the whole problem disappear just by choosing a smaller unit.  If I measured in microns everything would be large integers.

> Point 2. We had builders in last year to build us an extension. The architect gave them measurements to the nearest millimetre.  They measured out all their distances to the nearest millimetre which they were readily able to do using tape measures or laser devices. They couldn't lay a course of brick-work to precise millimetre accuracy, but no issue there. They preferred to start from the best measurement they could to keep any resulting errors to a minimum. 

They also couldn't measure the length of a room with a tape measure precise to 1mm.   Try getting three people to measure the length of a wall without telling their results and see if you get the same answer to 1mm three times.  

1
In reply to tom_in_edinburgh:

> Looks to me that if you give me a single reading with your baseplate compass I should assume it is +/- 2 degrees.

So surely 231 +/- 2 degrees  is a better starting point than 230 +/- 2 degrees or 235 +/- 2 degrees.

Maybe 237 would send me over the N Face.

In reply to tom_in_edinburgh:

> They also couldn't measure the length of a room with a tape measure precise to 1mm.   Try getting three people to measure the length of a wall without telling their results and see if you get the same answer to 1mm three times.  

Aye, but they'll be significantly closer than if they'd rounded their 10467mm up to 10470mm or (God forbid) 10500mm before measuring.

 You're making perfectly valid points — but none of them actually support your original argument. There's simply no justification for rounding a pre-determined bearing on the basis of measuring inaccuracies. All you do by doing that is add an inaccuracy before you even measure anything. Suddenly you're potentially three degrees off before you even go anywhere.

 Wicamoi 27 Dec 2021
In reply to Michael Hood:

Indeed. A lack of precision does not render avoiding bias unimportant. It is for that reason that archers always aim at the bull's eye, even though it is difficult to strike.

 Maggot 27 Dec 2021
In reply to tom_in_edinburgh:

Re: the horror Alpine story from earlier ... tech fails. In that case a flat battery.  How many Bank crashes have we had, for example, in recent years. You have such blind faith in tech.

Your rubbishing a given direction to only one degree as a reference point and ranting about resolution to 4 decimal places is bollocks.

In reply to tom_in_edinburgh:

> It's dishonest and unhelpful to do so because you give a false impression of the precision of the measurement.  

This is such a bizarrely small hill you seem willing to die on, which is ironic considering this thread originates from instructions on how to avoid dieing on a rather big hill! It seems odd that you are accusing the article of being dishonest and unhelpful when you say yourself you've not navigated off Ben Nevis in poor weather.

 Maggot 27 Dec 2021
In reply to TobyA:

And him and his ilk want to run their own small country 😄😄😄😄

3
 Martin Hore 27 Dec 2021
In reply to tom_in_edinburgh:

> >  The compass is the same. I can measure 231 degrees to the nearest degree - you do now accept that I hope -

> Well no, because you just posted a few hours ago an experiment where you tried to measure a bearing five times and you got 15, 14, 16. 15. 14.   Presumably that's in pretty optimal conditions in your house on a flat table.  If the correct answer is 14 then the error on your measurement of 16 is +2 degrees.  If the correct answer was 16 then the error on your 14 measurement was -2 degrees.  And you only took 5 measurements.  Maybe if you'd taken 10 there would be 13s or 17s as well.

The standard base plate compass (without a mirror) is a remarkably sophisticated piece of kit, despite it's apparent simplicity. It can be used in a variety of ways, each with different levels of accuracy.

The measurements I took, and you quote, are for taking a bearing from A to B from the map to use to navigate from A to B on the ground. The leg I chose was approximately 500m. so only 20mm on the map. It's quite difficult to line up the compass edge exactly when the two points are that close on the map, but I think I could get an answer to within 1 degree much of the time, though sometimes not.

If I try to point the compass at a distant object to obtain a back-bearing to help locate myself, an accuracy to the nearest two degrees is good going. Likewise, with my compass already set, if I sight on an intermediate object to walk to on the bearing, 2 degrees accuracy is probably the best I can expect, but in that case there will be a tendency for errors to cancel out over the whole leg.

But if what I'm doing is setting my compass to a fixed numerical bearing (eg 231 degrees) or reading a numerical bearing off my compass to tell someone else what it's set to (for example so we can check each other while following it), then I can be accurate to within 1 degree every time. And that's what's happening when we set the compass according to the instructions for Ben Nevis referenced in the OP. Yes the 231 degrees was originally measured on the map, but should be much more accurate than I achieved in my quick experiment. It will have been checked by a number of people, probably using a stand-alone, more accurate protractor, which I wouldn't be carrying or using in the field.

In all the above scenarios,  which occur pretty much every time I use my compass for navigating, I try to be as accurate as I can and would never deliberately introduce rounding errors. As Wicamoi points out - an excellent example - would an archer deliberately not aim for the bull's eye just because he can't guarantee to hit it?

Martin

In reply to Martin Hore:

> Yes the 231 degrees was originally measured on the map,

It could be measured very accurately using GPS position fixes taken in the field... If I was writing such an article, I might do that. Or use a larger scale map than the 1:25k.

 Martin Hore 28 Dec 2021
In reply to captain paranoia:

> > Yes the 231 degrees was originally measured on the map,

> It could be measured very accurately using GPS position fixes taken in the field... If I was writing such an article, I might do that. Or use a larger scale map than the 1:25k.

Yes, agreed it could be measured now using GPS in the field, and it's possible it has been. My OS Ben Nevis 1:25000 map certainly predates GPS. It has a 1:10000 inset of the Ben Nevis summit area which shows the relevant bearings as first 231 degrees and then 281 degrees, rather than 231 and 282, in the article linked from the OP. So, at some point, it was agreed that 282 was more accurate guidance to avoid the N Face and Five Finger Gully than 281. That could be for a number of reasons.  Perhaps a slightly different line is now thought to be better, or the same line has been measured more accurately, or the OS or Harveys have since mapped the area more accurately. Whichever, rounding to 230 and 280 degrees, while not making a lot of difference,  is certainly not going to increase accuracy.

Martin

In reply to Martin Hore:

> Whichever, rounding to 230 and 280 degrees, while not making a lot of difference,  is certainly not going to increase accuracy.

I wasn't, and haven't argued that. I've even posted a rebuttal of that idea.

In reply to captain paranoia:

> > Yes the 231 degrees was originally measured on the map,

> It could be measured very accurately using GPS position fixes taken in the field... If I was writing such an article, I might do that. Or use a larger scale map than the 1:25k.

It could.  And the architect could give the builders plans from the CAD system accurate to 1 um instead of 1mm if they wanted.  Or someone writing a book on Origami could tell you to fold at 11.23mm.  If you can't actually achieve that precision when following the instructions it isn't helpful, you are just giving people following the instructions a false impression of how accurate things actually are / need to be.  The benefit of the significant figures concept is that the measurement communicates not only the magnitude of the quantity but also the precision.

The number of people posting on this thread who have a false impression of how accurate compass bearings are is testament to that.  If measurements were given to less precision it would communicate what is actually happening better:  i.e. a fairly imprecise and error prone navigation method which is then corrected with reference to features on the ground.

6
 deepsoup 28 Dec 2021
In reply to tom_in_edinburgh:

I can't set a bearing of 231.0° on my compass, let alone 231.00°, but I can set a bearing of 231° just as easily as 230° or 45° or any other whole number of degrees.

Having done so I can be extremely confident that it is set somewhere between 230.5° - 231.5°, because on that kind of scale I'm pretty good at judging when a graduation mark is half way between two others to just about sub-millimetre precision.  Most people are.

Nobody here is suggesting that you need to correct between grid North and magnetic North you might have noticed, because currently the correction is less than a degree.  To set tenths of a degree you'd need a steering-wheel sized bezel or a vernier scale.

How accurately I think follow the bearing is moot - at the end of the leg I'll probably be a few metres off (at best, in my case).  But that's no reason why the point I was aiming at should have been a few metres off already before I even started. 

If I'm doing a bit of woodwork and trying to cut a mitre, even if I'm just following a pencil line with a hand saw and I know I won't be particularly accurate I still draw that pencil line at 45° as best I'm able.  If it's something that really only needs to be rough I might not even draw a line and just guess at 45°, but what I definitely won't do is get an adjustable set square out - an instrument that can resolve down to about a 1° precision and then draw a pencil line to follow at 44°.

 deepsoup 28 Dec 2021
In reply to TobyA:

> This is such a bizarrely small hill you seem willing to die on..

I think there's a bit of 'flat earth' psychology going on here.  The kind of thing where, having chosen a hill to die on, carefully argued rebuttals paradoxically just make a person all the more certain that they're right.  I think we see a lot of that kind of thing on here from many different posters.  Obviously on 'conspiracy theory' type threads but all kinds of others as well, and we're all at least a little bit prone to it because the human mind just works that way.

Sometimes a person will vehemently argue that black in white, day is night while the thread rumbles on.  Then just quietly change their mind long after it's been archived.  Climbing down at all, even admitting someone has any kind of a point, can be really hard while you're feeling like you're under attack.

 Howard J 28 Dec 2021
In reply to tom_in_edinburgh:

No one is claiming a degree of accuracy down to the levels you are talking about.  That level of precision isn't needed in real-world nav. 

You're forgetting about tolerances.  It's not actually necessary to get to a spot exactly 150m at precisely 231 degrees from the summit, somewhere in that vicinity will do.  However it's not really helpful to say "pick any bearing between x and y", not least because anyone setting their compass to one of the extremes who then wanders off course could end up in a dangerous situation.  It is much clearer, simpler and safer to give a figure in the middle of the possible range.

You're probably not going to die if you set a bearing of 230 degrees rather than 231, or walk 155 metres rather than 150.  However if 231 degrees is the optimum choice, and it's really no more difficult to set the compass to that than it is to 230 degrees (to the extent that the manufacturing tolerances of the compass allow), then why not recommend the optimum figure?  Is 230 degrees any easier to remember than 231? I would have them written down anyway, rather than rely on memory.

If you're that concerned about accuracy down to micro levels, you can reassure yourself the 231 degrees probably represents a rounding from a figure which could be expressed down to minutes and seconds.

I'm an advocate of GPS, but even a GPS is accurate only to within a few metres, and depending on satellite coverage and interference it can be far less.  Once on Tower Ridge my recorded GPS track was mostly accurate but there were several points where it put me in the middle of the coires on either side, presumably because signals were reflected off the cliffs.  I'm talking about errors of up to two hundred metres. 

Both GPS and M&C are simply tools which provide you with some of the data to find your way around, but you still have to understand how to interpret that data, and use your other senses and knowledge to build up a complete picture.

1
In reply to tom_in_edinburgh:

> And the architect could give the builders plans from the CAD system accurate to 1 um instead of 1mm if they wanted.

And the builders would be entirely unable to make use of that without rounding even if they could position bricks to within 1um, because you can't measure 1um with a tape measure or any laser measurer that you're ever going to find on any building site anywhere in the world. You can, however, set a compass to 1°. That is the crucial difference.

Likewise, if you plan a flight you don't round all of your tracks to the nearest 5° because it's unrealistic to fly to within 1° precision. You try your very best to fly the actual calculated track, so that you don't compound your flying errors with basic planning errors. If I started rounding all of my calculated tracks, my flying instructor would have a fit. And it actually matters in flying, because you're covering tens of miles at about a hundred miles per hour, and any error in track quickly results in a large absolute position error. So that extra 2° ambiguity you've introduced could easily result in being 5nm off track on a long leg. Or, in other words, in someone's airspace.

Edit: and for the avoidance of all doubt, by nm I mean nautical mile and not nanometre...

Post edited at 11:40
1
In reply to deepsoup:

In your woodworking analogy saying 231 degrees rather than 230 degrees is like telling somebody to cut on 46 degrees rather than 45.  Why would you say 46 degrees unless you really meant they were supposed to be accurate to +/- 0.5 degree?  If you said 45 they'd realise what you wanted and that you weren't asking for absolute accuracy.

Same if you said 'meet me at 2.31' instead of 'meet me at half two' or 'meet me at 2.30' there's an implication that you actually expect that level of precision.

3
 wilkesley 28 Dec 2021
In reply to UKC/UKH Articles:

I wish I had seen that years ago. The link below is an account of us getting lost after climbing Glover's Chimney circa 1985 and ending up someway down Glen Nevis.

http://thecastle.github.io/thecastle/pages/23_Benighted_on_the_Ben.html

 deepsoup 28 Dec 2021
In reply to tom_in_edinburgh:

> In your woodworking analogy saying 231 degrees rather than 230 degrees is like telling somebody to cut on 46 degrees rather than 45.

Not unless it is your contention that 231° is actually incorrect and 230° is correct - but you would seem to be changing your tune if so.  I thought you'd been saying all this time that 231 was unreasonably precise (but not actually incorrect) and therefore might as well be rounded down to 230.

45° is the correct angle to cut a mitre if you're looking to make a square joint, not 46°.  In my woodworking analogy you seem to have been equating saying 231° with asking a carpenter to cut a mitre at 45.00° - ie: still 45° but to a degree of precision that you can't possibly achieve in practice.

Marking out = setting the compass bearing.  Cutting along a pencil line = walking along the bearing.

Even though I'm not the best at cutting along a pencil line without any kind of physical fence or guide, I still make the effort to mark the pencil line as accurately as I can to maximise my chances of making an accurate cut.

Purely by eye I doubt I can cut better than 45±5°.  Just using the square built in to the handle of a hand saw might allow me to mark a pencil line at 45±1° (which I can then follow with a hand saw to within about ±1.5°)  Good enough for a fence in the garden maybe.

Using a mitre saw might achieve 45±0.5°, which will do for a bit of architrave or a small picture frame.  If you're fitting a kitchen and making a mitre joint in a worktop you don't use a saw at all, but cut it using a router and a jig, perhaps achieving 45±0.1°

In every case you aim for 45° precisely, but only to the best accuracy achievable with your measuring/marking instruments, and then you cut to the best accuracy achievable with the tool that you're using (and your skill in using it).

Whether I can pace-out and walk a 150m leg on a bearing of 231° is moot - I absolutely can set a bearing of 231±0.5° on the bezel of my Type 4 Silva compass.  So why on earth would I not?

Post edited at 14:40
 Howard J 28 Dec 2021
In reply to UKC/UKH Articles:

Out of curiosity I've plotted an alternative descent route in Basecamp, using 230 degrees followed by 280 degrees, ie rounded off to the nearest 5 degrees as Tom has suggested.  The red line is the "official" recommended route, the black line Tom's alternative. 

For the first leg rounding doesn't make much difference.  The second leg brings you significantly closer to Five Finger Gully, I estimate by between 30-50m from the recommended line.  On paper you're probably still a safe distance from the gully, but in the real world with a natural tendency to deviate downhill that might turn out to be too close for comfort.  

Perhaps in Tom's mind the rounded figures seem tidier and maybe easier to remember, but to me they carry no more significance or conceptual weight than the recommended bearings, and are no more easy to remember.  Besides, I'd have written these down on the map before setting out rather than rely on memory. It's no more difficult to set the compass to these numbers than to the rounded ones. I'll stick with the recommended bearings, thanks.


 Martin Hore 28 Dec 2021
In reply to captain paranoia:

> I wasn't, and haven't argued that. I've even posted a rebuttal of that idea.

Sorry if you thought that comment was critical of you. I've no criticism of your post at all. I was just re-enforcing the case that both of us, and all but one of the recent posters on this thread, have been making.

Martin

 Sean Kelly 28 Dec 2021

Perhaps some ought to read the advice proffered by Andy Nisbet in the selected Scottish Winter Climbs guide p.108 where he recommends 230 degrees Grid followed by 280 degrees Grid. So anything between 230 - 232, and 280 - 282 degrees allied with the correct pacing should arrive at the Red Burn. Some GPS and Navigation apps are only good for a 6 figure GR...that's a 100-metre square of uncertainty somewhere on the Ben plateau. Trying out various Altitude apps gave vastly differing readings. OS locate is apparently accurate to within 15 metres. Can you figure that on a 1:25,00 map? How big is the Gardyloo cornice? I know because I have tunnelled through it. How often has your car-fob frozen when you get down, or the camera refuses to work in the cold. Ask the MR how many that they assist, after having got in trouble on dangerous ground because of relying solely on a GPS phone app?

But then sometimes shit happens...

In the 70s I twice ended up down Five Fingers Gully, in the dark (we were held up by very slow parties on our chosen routes), in atrocious weather both times. The first time I didn't realise that I was in FFG and somehow despite faltering torchlight we made it safely down. The second occasion  in really desperate weather, fully frozen up with frosted eyelids, a howling wind, desperately cold temps we ended up in the higher reaches of the gully. Having dropped about 500 feet or so the conditions eased somewhat, so we decided to carry on down rather than face returning to the wild plateau and raging blizzard. We kept trying to traverse right towards the Red Burn, but the ground became much more difficult. We briefly considered digging in, but a long Scottish winter night didn't appeal. My torch gave up, and so we continued the nightmare descent with snowballing crampons traversing all the gullies. And then we hit a vertical wall of ice. We abbed off a snow bollard and eventually ran out onto easier ground. Then we had to cross a raging River Nevis...

Over the following weeks two more teams descended by this way and there were a number of fatalities (4?). When the weather conditions on the summit plateau are truly awful, navigation is incredibly difficult. The wind and snow are buffeting you. Every little task takes an age as nothing is simple. Trying to read a map is almost pointless unless in a map case, or a small part is laminated. If you have to wear spectacles it is well-nigh impossible to glean any detail off the map. The instant you remove your gloves they freeze solid, and any limited warmth in your fingers takes an eternity to soften the glove to fit the hand again. You are tired, concentration is difficult, and you might be thinking the worst. OK, equipment is better, we have  waterproof maps, better torches, gore-tex clothing and the rest. But even with all this advantage, it is still going to be a chastening experience.

Sitting in the warmth at home pontificating about how to best navigate down from Ben Nevis in wild winter conditions is beyond the experience of a lot of posters on this site. And some have even admitted to not having even been on the Ben in winter, yet persist on peddling their pedantic crap over this and that.

When you have the T-shirt, feel free to post your views, or better perhaps read the full article first. It could save your life!

Post edited at 17:34
3
In reply to Sean Kelly:

> Some GPS and Navigation apps are only good for a 6 figure GR...

Get a better one, then. 'Grid Reference' by Arthur Pembleton, for instance; free, tiny, does what it says on the tin. Configurable # of digits, from 1/2 (10km) to 5/10 (1m).

Bear in mind the accuracy of GNSS. Be aware of potential failings with shadowing and large reflecting outcrops/buttresses.

Post edited at 17:49
In reply to captain paranoia:

Careful not to relay the wrong format grid ref when it all goes wrong! It's been known for operators to use a 6 fig when it was actually an 8 being phoned in = helicopter in the wrong place.

 Martin Hore 28 Dec 2021
In reply to Sean Kelly:

Sean

Thank you for reading the thread and posting again. Your article is very useful, and timely. Yes, I read it all.

Having followed the thread, and made several contributions myself, my impression is that the majority of posters, at least the later ones, do have relevant winter mountaineering experience, and largely concur with your views. Yes, one poster has specifically admitted to not having been on the Ben in winter. However, he has, I think, been largely a lone voice in his claim that bearings such as 231 and 282 degrees should not be quoted because (a) they cannot be set on a base plate compass with that degree of accuracy, and (b) they lead people into a false sense of security that this implied degree of accuracy can be achieved when walking on a bearing in practice.

I and many others have argued that point (a) is just wrong, and point (b) is confused. Most people with any experience of mountain navigation do know that you can't reliably walk on a bearing with one degree accuracy, but that doesn't stop us trying to reduce unnecessary errors by being as accurate as possible at all stages, and in rough conditions on the Ben in winter that means having two accurate pre-determined bearings - the ones quoted in your article - and setting them as accurately as your compass permits. As you rightly say, you may struggle to read your map, and your GPS phone may cease to function, but you should still just about be able to hold a compass bearing with sufficient accuracy to get off the hill, particularly if you have a picture of the terrain in your mind, gleaned beforehand from the map and from reading articles such as your own.

From your profile, we're about the same age. My experience is almost certainly less than yours, but not negligible (and I have made it up Left Wall (!)). In 50 years I've probably had no more than ten or so full winter days on the Ben but these have included at least three descents from the summit in darkness and at least one in a white out. On each of those occasions the predetermined bearings were extremely useful. So you deserve a big thank you from me for re-publishing the bearings in such an informative article.

With respect to the one poster who has doggedly stuck to his solitary opinion throughout,  I think deepsoup's earlier observation is pertinent, perceptive and worth re-quoting:

"Sometimes a person will vehemently argue that black is white, day is night while the thread rumbles on.  Then just quietly change their mind long after it's been archived.  Climbing down at all, even admitting someone has any kind of a point, can be really hard while you're feeling like you're under attack."

Martin

1
In reply to Martin Hore:

Before trying the appeal to authority thing perhaps consider three things:

a. You failed to read a bearing from your map accurately in your house.  Your own experiment with five readings was +/- 2 degrees.

b. Someone else posted a reference which stated that Alpine guides practice was to use a GPS app on their phone in conjunction with phone cases, backup batteries and a backup GPS.  Alpine guides are more qualified and operating on larger and more dangerous mountains than the people pontificating here.  I'm actually surprised at people using phones in these circumstances: they clearly are not qualified for the temperature range and I'd have expected them to use more specialist items.

c. Someone posted a reference that Andy Nisbet in Scottish Winter Climbs recommends 230 deg and 280deg.  I'm guessing that Mr Nisbet was on the Ben in winter quite a few times.

d. A lot of this compass vs GPS argument is old people nostalgic for old tech and giving experiences with previous generation GPS tech.  This stuff gets better quickly.  It reminds me of the Kindle vs paperback book debate.  It will get resolved by market forces, eventually paper maps will be niche items like old records and cassette tapes.

e. My point isn't about mountaineering it is about how many significant figures are appropriate in a measurement.  The complicating issue here is that degrees are not a decimal measurement so you can't easily apply the standard rounding methods that you would to SI units.

Post edited at 09:23
2
 Howard J 29 Dec 2021
In reply to tom_in_edinburgh:

Nisbet's guidebook was published in 1996.  Since then the recommended bearings have been refined to 231/282 degrees, which suggests that this difference matters. These figures were not made up for this article, these are the figures published in more recent guidebooks, in the advice leaflets available in Fort William, and printed on the Harvey's maps.  They are the figures in my 2002 guidebook written by Alan Kimber, who also knows the Ben intimately.

I think many of us were surprised to learn that Alpine guides rely on phone GPS.  However that did not end well, and is hardly a recommendation.  The advice for the UK is consistently to not rely on phones, which are usually not robust enough to withstand typical British weather conditions, and you really need a dedicated GPS unit (many of which now include mapping).  Alpinism is very different from British mountaineering.  Usually in the Alps you simply don't go out in adverse weather - another mistake made by the guide - so perhaps a phone is normally adequate for their purposes. 

You talk about rounding. We are rounding to the nearest degree, which is the best that can be achieved with the equipment we have to hand.  It is recognised that in practice it is impossible for even an experienced navigator to follow a bearing with 100% precision, but if you don't set it accurately to begin with then you have no chance.  A user error of say 3-4 degrees off the exact bearing is probably acceptable in most real-world situations.  However if you've rounded off to the nearest 5 degrees, and then add user error to that, you could be as much as 8 or 9 degrees off course.  This could well be significant, and on the Ben would probably bring you into Five Finger Gully, which is exactly what this is intended to avoid.

 deepsoup 29 Dec 2021
In reply to tom_in_edinburgh:

> My point isn't about mountaineering it is about how many significant figures are appropriate in a measurement.

Yes/no question: do you accept that it is possible to set a bearing of 231±0.5° on the bezel of an ordinary baseplate compass? (ie: accurate to within the nearest one whole degree.)

For example the Silva 'Type 4' compass I have right here.
https://silvasweden.com/collections/compasses/products/expedition-4#specifications


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