Three basic enquiries

[AndyJWest]

Where it really matters you should be working with CAS or EAS not IAS.

Yes, of course you're right, though having to explain the difference, and all the complexities involved, seems a little OTT in this context, I'd have thought.

Actually, I'm not sure that as far as IL-2 is concerned, IAS and CAS would be any different in any case, though I don't know how you could prove it one way or another.