Here is the full list of all 21 Death From Above achievements.
Visit all locations at the training grounds
Raise all of the flags in the level
Neutralize 50 soldiers
Your drone was lost in battle
You got defeated by a tank
You were defeated by a convict
Destroy 10 tanks
Neutralize 25 soldiers
Neutralize 10 soldiers
Neutralize 4 enemies in a short time
Fly through a garage building with the FPV drone
Destroy a convoy of enemy vehicles
Collect all NAFO Fella collectibles
Explosion of a vehicle kills an enemy soldier
Clear all minefields in the level
Hit the Russian drone with the FPV drone
Achieve Mission 5: Missile Rush mission without penalty
Drop a stolen washing machine on an enemy soldier