I was drafted out of a residency and sent to Vietnam where I served my year as an army flight surgeon. I'll not mention the year or place of my postings hoping that victims' identities will not be apparent to their survivors in this article. For those interested, I revealed these details in my book "A Brewery Workers Boy in Vietnam."
There were three incidents.
We refurbished helicopters at my army posting. Specially trained pilots had to test fly them stressing them to the extremes before general use. One evening (against rules, test flights were to be done during working hours) the two pilots started to take the "new" Huey up, but the crew chief (not trained to fly an aircraft ) sat in the place of the co-pilot. The actual co-pilot and some casual intruder sat in the back taking a night ride on a risky flight just for the pure hell of it. It crashed at the end of the runway; I remember seeing the fuel flaring off in the night. The aircraft itself was buried in 10 feet of mud. Every bone in the 4 bodies was broken. Analysis showed that during a maneuver to stress the hydraulics, the "co-pilot" had turned the fuel valve off instead of the hydraulic valve which was adjacent and looked similar. Bad mistake.