Your first encounter with the enemy ace is in the 4th mission of the Eastern Winds campaign; The Battle of Kursk. Playing on easy and using
for Ace mode should make short work of him.The Battle of Kursk
After shooting down the bombers, the enemy ace will appear, he'll shoot down one of your comrades in a cutscene, then it's your chance to retaliate. If you turn towards him quickly you could take him out straightaway with your MGs or a well placed rocket. Otherwise he's no real challenge even if you're using the Petlyakov. When you shoot him down he'll be forced to bail out and survive, this time.Rise of the Jetfighter
You'll encounter the ace again in the final Eastern Winds mission. Head into the mission and start destroying the enemy tanks- destroy at least '25' with your cannons for a medal. After the tanks are all gone you'll be asked to land on the airfield, but when you reach the marker a cutscene will take over where the enemy ace will attack you in an Me 262A. Just like the previous fight however, he is no real challenge on easy, just get behind him, slow down and use ace mode to guide your shots.
As soon as the second cutscene ends with the death of the ace the achievement will unlock.