You can see the aerial skins upon entering the vehicle depot in an aircraft battle. By default all of the skins are locked, unless you have obtained them during the quests. If you posses an aerial skin you can change it and your appearance on the battlefield will be different.
The Ghostwing was obtained by earning a remarkable number of prestige points in the celebratory anniversary challenge following the 10th anniversary of eRepublik. Rise above the clouds and show your enemies the sky is no limit for your greatness. Let's turn and burn!
The ER-11 Skycutter was obtained by completing the 11 years anniversary challenge. Hunt down your enemies in rapid fire and rise well above the sky to dominate the fight with the ER-11 Skycutter!