UKC

Hi. We're going for a hiking trip to french alps this summer.  Not been on a plane for a while.  Can anyone recommend a good hiking backpack I can fit under seat 45x36x20 and be able to use on day hikes when there. Been looking at the gregory kiro 28.  I know it's too long but would I be able to squash this in the sizer at airport. Thanks. 

A 25L OMM bag is a decent option. Take out and wear as much as you can. Squishes down small. 

Normally taking the back-reinforcing out makes the rucksac small enough. Put it in a large(r) (2nd) cabin-bag. Worked for last 2 flights.

The Alpkit Gourdon backpacks are worth a look. I have 20L and 25L version and ice used them for exactly this purpose.

The budget airlines have recently got very strict on dimensions of under seat bags. I wouldn’t risk it, pay a bit extra for a larger cabin bag for overhead locker

Dimension wise this pack from Simond fits perfect, fly fairly regularly with easy jet and never had a problem.  https://www.decathlon.co.uk/p/mountaineering-backpack-22-litres-sprint-22-g... out of stock but perfect if they get it back in.

Take note of the fact that in some bags they can be very hard if not impossible to refit so if going down this road make sure it's one where this is possible by design. 

Agreed... Both of mine are. Best to check in the shop that the "rigid" part of the back can be removed and replaced easily.

I take a KarrimorSF Sabre30 on Easyjet regularly and never been pulled up for it.  Probably fits lots more stuff than the equivalent Deuter with an air gap on the back.  I'm sure I can pull stuff out to make it fit if I get hassled.