The 1994 RAF Chinook (serial number ZD576) crash in Scotland is said to be one of the worst (or even the worst) Royal Air Force (RAF) disasters, although it took place in the context of the Irish Troubles. Four crew and 25 passengers perished when the helicopter crashed in foggy conditions in 1994. 30 years later, the families of the victims are saying the British Ministry of Defence (MoD) is letting them down by not providing a memorial.