The Airfield is a location of Covert Front 3 near Zurich. It is close to Manfred his headquarters.
The airfield seems to be owned by Manfred Nikolai, or the Kaiser's Intelligence Services. A lot of planes are being stored there. It is on Swiss soil, which makes the situation a lot odder.
After escaping from the prison, agent Kara
stole one of Manfred's planes to fly to Lisbon
to search Von Toten
. The airplane is an AGO C II
. Which seemed to be planned by Manfred.