Read it again Bizjetjock,
Aircrew has nothing to do with it as long as you don't make at least 6 trips to the UK starting/ending in the UK.
Your fine with overseas employed and 90 days.
Even with the family ties stuff your fine as long as you can prove you have a home that you live in overseas and make sure you don't come back more than 90 days etc.
If you work for a UK based company and receive UK derived income then its a very different matter even if you live in Outer Mongolia.