I agree with the points made about aircraft wreck recovery being relatively unfruitful for archaeologists, since the aircraft themselves are fairly well documented, and we often have complete surviving examples for study. So any new information is going to be second-order at best. That’s would be less true when it comes to fortifications and civil defence sites, I think, because there would have been much more scope for variation, probably less documentation and less interest in preserving it, and perhaps most importantly, there would be a range of social/cultural information about how the sites were used and sited which by definition doesn’t apply to a crash site. Still, many of the issues are pertinent in both cases (e.g. qualifications, reporting).

It’s long, so it’s worth sitting down with a cup of tea or a stiff one, as preferred!

http://forum.keypublishing.co.uk/showthread.php?t=89006