A/C

19:37 Apr 6, 2017 

I do understand — I work for a major software publisher who often asks me to translate random strings, often abbreviated, AND riddled with typos to boot :-/

However, you say this is a 'subscription form': does that mean the form a customer will use to 'subscribed' to this software (instead of, say, buying it outright)? If so, one can envisage that the number of A/C might well affect the price — either as a deliberate sales policy, or simply beause the software is necessarily more complex / expensive the more planes it can handle.
Likewise, as I mentioned in my suggestion, the price of the subscription might be weighted differently according to, say, the types of planes in your fleet, explaining the 'coéfficient' aspect.

19:25 Apr 6, 2017 

I'd also suspect A/C doesn't need translating, but the "coéfficient" puzzles me, with Tony's suggestion. You could ask the makers of the software, who seem to be American...?

18:52 Apr 6, 2017 

Yes, it makes sense.

I feel your pain with regard to context. This is all I have, really. It's a longer document which discusses the bidding process (for a vendor who wants to add features to this software), then it suddenly shifts into this list of terms with no context. It's in wordfast, so there really is no other context. I always post all the context I have.

18:21 Apr 6, 2017 

It's really impossible to tell without a great deal more of your context; just saying this is a 'form' doesn't really tell us much, we need to know what exactly it is for, how it is use,d what the other details are on it, etc.

I have a strong suspicion this is just the very common EN A/C for 'aircraft', which is pretty universal internationally across all languages; it could also be 'aircrew', but that is perhaps less likely given the apparent context.
Please tell us if this might make sense?