I don't believe it's a question for this place, but I'll answer.

aircrew overalls and jackets are designed to fit the pilot in his work environment. during flight pilots are seated and generally are strapped in, so no walking and standing around. also older fighters are quite cramped, so little place to put charts, maps, notes, checklists etc. so they have a lot of pockets anywhere that can be reached in a seated position, that also explains why pilot overalls have ankle pockets.

over the overall, the pilots might also wear a G suit (in fighters) and a survival vest that has some gear placed in pockets needed for survival in the case the pilot must bail.