While younger people won't care, older people rarely grow out of their original beliefs. Of course, it is an employer's duty to treat everyone fairly, but there is no necessity for an employer to know.
As for your colleagues, what bearing does it have upon them. Little to none really - when you socialise with people and go to the pub / club with them, you rarely hear anyone announcing "by the way - I'm heterosexual" in civilian / military life. Why should it be different if you are gay?
There are of course those of both sides who wear their sexuality as a badge - different girl every Friday / different chap every Friday - if that is you, and the way you want to behave when off duty, so be it - you will be judged for the tart that you are, not for your sexuality.
However, if you are are more normal character and associate with people who are balanced, most of them won't care if you are out or not. Basically, if you want to be defined as "gay", then by all means announce it. But expect people to be prejudiced - it is reality that many are.
If on the other hand, you want to be judged as a team player, great chap, great pilot, then work hard to define yourself as that. If people afterward meet your partner, they won't define you as gay, but the team player, great chap, and great pilot you always were - if they behave otherwise, they weren't worth knowing.