The subject of the original query was Harrier GR.Mk.5 ZD325, the 6th production aircraft. The accident happened on 22-Oct-87. I was a junior FTE at Dunsfold at the time.
I'm interested that
mrwickets refers to
selecting manual separation instead of emergency oxygen
and
John Farley to
two main scenarios
as it is generally the wander-lamp theory that is remembered, as in
RJM's post.
I think it is noteworthy that the man sep and emer oxy handles on the Mk.12 seat are of similar shape, on opposite sides of the seat, whereas on earlier seats emergency oxygen was selected by pulling a knob or a ring-shaped handle; further, that the emergency oxygen gauge is on the opposite side of the seat to the operating handle, i.e. in close proximity to the man sep handle.
As I recall, a test of the emergency oxygen system was briefed for the fatal flight. Of course, there should be an interlock which would have prevented the manual separation handle from being pulled up by mistake while the seat was still in the aircraft, so this would need to have failed, but in my view this was as plausible as the wander-lamp explanation, and I believe contains lessons on ergonomics and man-machine interface design.
Agree with the sentiments expressed about Taylor - a top bloke.
Rhys.