Spanish to English Tech/Engineering Aerospace / Aviation / Space

There has been a discussion of this term previously, with the term chosen by peer agreement being "airfield": http://www.proz.com/kudoz/spanish_to_english/other/2474068-c...

The answerer did ask for more context and this was not forthcoming (although the asker did originally say it was "part of an airport"). For me, an airfield is a more general word than airport and the word is often applied to smaller or more specialised facilities where "airport" would not be appropriate. I suppose an airport is a large airfield for general use with superior facilities.

The context I have is a document certifying the participation of a particular company in the "ampliación del campo de vuelos del aeropuerto de ***". This project included a number of different construction jobs on the "air side" of the airport, principally the runway, taxiway etc., but not the terminals or hangars. I note that one experienced translator in the previous discussion was adamant that a campo de vuelos is not part of an airport, but maybe this is a peculiarity of European Spanish.

I don't think it makes sense to speak of an "expansion to the airfield of an airport" but maybe I'm wrong and I'm not sure what the alternative is.

Thoughts?