Hi SG500,Using a digger to recover crashed aircraft seems a bit heavy handed but believe me in most cases it is necessary,but it must be done with care or important items will be destroyed,I have in the past recovered a crashed P47D,the engine of which was 18ft deep,other planes,(Spitfire,Master, etc,)at lesser depths,one constraint is time,the landowner does not want a big deep hole in his land longer than is necessary,water seepage is also a problem,the best way if time etc,permits is to excavate around the wreckage leaving a column of compacted wreckage which can then be disentangled and recovered with care,but,,,if the plane crashed at an angle this would mean a huge hole taking lots of time,(diggers usually charge by the hour) plus a larger hole takes longer to fill in,Time Team and other tv progs have loads of cash they can throw at the project,the usual method using a digger is to dig down and follow the trail of wreckage but this does destroy a lot of useful items and information,another instance where time is of the essence is when wreckage has been recovered (especially from peat bogs),and starts to dry out the paint just flakes and drops off,which again will lose valuable and interesting information,such as paint samples or the aircraft ID number painted on engine cowls,armour plate etc,or in some cases the nose art,with most recoveries time is a big factor,and now Health and Safety is another constraint,when I was doing it H&SE was not even heard of,
Hope this is of use,
Cheers,
Don,