Question:
In FitE/SE,  what happens to air units surrounded in a
pocket, and the pocket is out of supply?
Supply rules just say units, with special supply listing an RE amount
that can be carried by aircraft, but aircraft only have an RE Equivalent
listed in the Section on German’s operating in Finland, where each air
unit counts as one RE.

Answer:
Air units didn’t need supply until an optional rule was introduced in
WW. So if using FitE/SE, just ignore them for supply calculations.
They never run out of supply.

Source:
Posted by Bill Jenman (bill.jenman@gmail.com) on the EuropaAssociation Mailing list at Yahoo, April 21st, 2015