Slitherine

In the "Along the Volga" scenario you have a german ally. This ally also captures cities and airfields, which are then unusable by your aircraft as you do not own them. This is undesirable as it makes it impossible to move your own aircraft up. I assume all city related features like external transports also won't work on allied cities.

Suggested fix: Allow usage of allied airfields and cities.

This is slated for next patch.

'Share airfield' is a tick box in scenario configurations.