In reply to mutt:
Coming home from a long-haul work trip last year - not something I make a frequent habit of thankfully - I was sat next to a man who makes that same journey to the Middle East, return, every fortnight or so. All year round. Many of my colleagues are on long-haul flights weekly. All year round. Hundreds of flights currently depart the UK monthly without passengers for entirely indefensible commercial reasons.
In absolute moral terms, making a climbing trip to India isn't great. In relative terms it doesn't even register, and as a one-off experience I'd say has the potential to enrich one's life far beyond the impact it makes on the planet.
One has to pick the right battles. Being righteous at those making once-in-a-lifetime and potentially life-changing trips abroad isn't going to help, and isn't going to change a single thing. And aviation is but a small part of the equation. Do you eat beef or dairy, for example? Would it be fair for me, as a vegetarian, to preach at every opportunity to those who do eat beef? Would it be fair for my vegan friends to preach at me at every opportunity for eating dairy?