Derek describes the accident:
"On the 26th February 1967 45 Commando RM were 'up country' in Aden with the main unit base at Habilayn Airfield. I was tasked to fly the unit photographer, Mne Musgrove, to the Wadi Bijayr where 'X' Company had found a weapons cache. We took off in Sioux XT 219, and were soon in the area, but were unable to locate an 'X' Company landing site. The whole company area was on either side of a very steep wadi, and there were no obvious places to land. I approached one possible landing site, but from a high hover it turned out to be well out of limits for a Sioux sloping ground landing. As I began to transition away there was a loud crack, the Sioux rolled to the right, and the cyclic stick went loose. The next thing I remember is being outside the Sioux, looking at the wreckage! Try as I might, I cannot remember how I got out, as I must have been upside down, and over a steep drop. Neither Mne Musgrove nor myself were hurt, and he began taking photos of the crash site. I returned to the Sioux briefly as the engine was still running, and there was a trail of smoke.
The Board of Enquiry had difficulty examining the Sioux, which had to be roped to a rock to prevent it rolling down into the wadi, and parts of the rotor head were missing in what was 'Bandit Country'. The local tribesmen claimed to have shot the Sioux down, and they certainly found bullet splash in the immediate area, but with 'X' Company around this was obviously a false claim. Two of 'X' Company personnel, Sgt Brian Young and a USMC exchange officer who was also a heli pilot, were looking down on the scene from the other side of the wadi, and reported that the rotor appeared to stop before the Sioux inverted. The Board's findings were that the accident was caused by 'an unknown technical defect'. There were two other identical crashes in New Zealand with Bell 47s, but neither produced a definite cause.
I still find it unbelievable that a Sioux, or any helicopter for that matter, could invert like that, on a slope, and yet not thrash itself to pieces. As it was, it was only the fact that one of the rotor blades stopped immediately pointing down the slope, that prevented the wreckage falling into the wadi. The other blade was along the tail boom. I have seen many videos of helicopter crashes, and in all cases, as soon as the main rotors hit the ground, or water, there is an instant reaction that causes extensive damage to the helicopter.
The patron saint of helicopter pilots was obviously sat on my shoulder that day."