Here is the full list of all 23 Frequent Flyer achievements.
Fly 1000 games!
Get total score of 500000
Fly 500 games!
Fly 100 games!
Get total score of 250000
"Spitfire" plane unlocked!
Destroy 50 minelayers
"Pe-8" plane unlocked!
Get total score of 50000
"Il" plane unlocked!
Get 5000 score in one game (infinite/organized mode)
Get 2500 score in one game (infinite/organized mode)
Destroy 50 flying bombs
"Sabre" plane unlocked!
"Me 262" plane unlocked!
Destroy 100 zeppelins
Destroy 50 scout planes
Destroy 100 rockets
"Messer" plane unlocked!
"Mustang" plane unlocked!
Get 1500 score in one game (infinite/organized mode)
Get 500 score in one game (infinite/organized mode)
"Lock" plane unlocked!