I have made a few rules for player skills and are open to more suggestions.

Basicly are there 4 kinds of abilities: Pilot skills which only pilots can have, Gunnery abilities which any crew member can get, Observer abilities which only observers can have and Ace abilities which are more powerful and are based on shot down planes (In our current campaign we also count balloons but it isn't working so well, in the next one only planes will count.

The 3 first are awarded when you reach a certain number of experience points. 100, 250, 500, 750, 1000 and so on.

You get 25 xp for shooting down a plane, 10 for a ballon, pilots get 10 xp for observing or bomb something while observers get 20. Both gets 4 XP for every turn they strafe a trench and dring certain missions the get 1 xp for every hit (damage card that does at least 1 damage). Pilots will also recieve 1 xp for every 4 movement cards you use.

Here is the current abilities:

Pilot abilities:
Cannot be tailed. Only aces can tail the pilot.
Maneuver: Pilot can ignore rules like not doing 2 steep maneuvers in a row or that he must do a straight after an Immelman.
Tailing: The pilot can tail twice the normal range.
High connections : The pilot knows some people in high places and will always get his plane one month before it is officially released.

Gunnery abilities:
Unjamming: The gunner unjamms faster. He can take this ability twice, for 1 time he is unjammed 2 rounds, the second time is he unjammed only 1 round.
Added damage : The gunner will make 1 damage extra if he does 3 or more damage. Remember to tell the person you are shooting this.
First strike: If the pilot shoots down the enemy it doesn’t have the time to fire back.
Dogfighter: The Aim Bonus is ignored when firing at this plane. (thanks to IRM)

Observer abilities :
Observing : The observer can observe on altitude 3 also and can even observe if he is wounded.
Bombardier: The observers bombs will do full damage instead of half if the target cards hits partially.

Ace Abilities:
Range: The Ace can fire 1 ½ times as long (you might want to make a special ruler for aces).
Well taken cared of machine guns : the ace can choose to discard a card with the jamming symbol on and draw a new instead. He can only do this one time each turn.
Quick reaction: The ace can choose to change the last of his three cards. After ha done it once he cannot do it again until two full turns have passed.
Luck: The ace will survive when he should die. He will wake up in a friendly field hospital and be out of the game for 2 months. This ability will work in all cases except an explosion. This ability will only work a single time

I am open for suggestions, but the abilities shouldn't be too powerful. They should be an edge but not tip the balance too much.

Any ideas?