This term is used throughout military parlance like DBR or CAT 5 is
An aircraft is like everything else in the Armed Forces it has to have an inventory number whether it be a new chairleg, an engine or an aircraft it has to be accountable to either a stores section or a squadron, when a chairleg has been broken it is replaced by a new chairleg but if the whole chair is broken it is replaced by a new chair, therefore it is struck off the inventory or in the case of an aircraft Struck off Charge from the Squadron and RAF.
Damaged Beyond (Economical) Repair (DBR) means just that, if an aircraft is too far damaged it is struck off charge and the the salvageable parts are retained and the remainder is scrapped usually under a civilian contract.An aircraft that may have been lost in an accident might not necessarily be struck off charge for some time, each accident has to have a Board of Inquiry (BoI) set up to find the cause of the accident, often this would involve gathering all the retrievable parts from the site of the crash, remove those parts to a suitable aircraft hangar and painstakingly reassemble the aircraft like a jigsaw puzzle, this could take weeks or months depending on the size of the crash site. Once a cause has been established, and more than likely a cause is usually found, and the BoI reports its findings, the Air Chiefs decide the aircraft can be struck off charge. In the case I was involved in Hastings TG579, although the crash (landing in the sea?) occurred on 1st March 1960 the sequence of events were that it was SOC on 23rd February 1961 a year but a week from the accident.
Similarly Hastings WD497 that crashed at RAF Seletar with the loss of all on board, on a supply drop on 29th May 1961 was not SOC until 29th January 1962 some eight months after the accident. Coincidentally the same Admin Officer Struck this aircraft off as the above TG579. So when you see a SOC date stated that is the date the aircraft was no longer on anyones inventory, the aircraft in question may not have flown for months or even years before being struck off. The RNZAF aircraft above are perfect examples!
If an aircraft was Damaged Beyond Repair but was a complete airframe with wings that could be used for training purposes, i.e. airfield fire fighting, extricating the casualties from the wreckage or storming a hijacked aircraft then these shells would be used until such time as they had no useful life left.
