Here is the full list of all 24 Air Conflicts: Secret Wars (EU) achievements worth 1,000 gamerscore.
Every mission completed
Chapter VII Completed
All planes unlocked in single player campaign
Chapter VI Completed
Scored in top half in Deathmatch with at least 6 players
Scored first in Deathmatch with at least 6 players
Chapter V Completed
50 multiplayer matches played
100 players killed in multiplayer
5 multiplayer matches won with Great War Team
5 multiplayer matches won with Red Air Force team
5 multiplayer matches won with RAF team
Chapter IV Completed
100 ground units destroyed in Campaign Game
5 multiplayer matches won with Luftwaffe team
Long range Rocket Kill in Multiplayer
10 players in multiplayer killed without being shot down
5 players in multiplayer killed without being shot down
Extra long range Rocket Kill in Multiplayer
Chapter III Completed
100 aircraft shot down in Campaign Game
Chapter II Completed
Enemy aircraft shot down in single player with rocket at great range
Chapter I Completed