ShyTorque
RE the trust of DME systems, I picked up this impression over time from various publications, manuals, etc – did not expect any argument on it, you do surprise me but I do not argue your experience – have you asked anyone you know who flies/has flown North sea or Navy helos?
Walter, I can tell you that they would place
some reliance on such a system, but coupled with a ground mapping / surface radar, but what relevance to an
RAF SH trained crew do you think would that be?
Bear in mind that I fully understood the RAF training system at that time, as an SH instructor and I didn't just "pick up impressions" from books. Any crew using a DME system, VFR or IFR, would
not rush towards a landing point at 160 kts in the climb, which was as fast as a Chinook helicopter can go in straight and level flight, or probably in a slight descent.
It is totally logical for a helicopter crew to slow down and remain in visual contact with the surface when operating in deteriorating weather conditions; that is how RAF SH has traditionally operated (there is no other logical way to do the job if you intend to land) and that is what this crew were trained to do.
How this Chinook got to 160 kts at the Mull, from a low airspeed, where the yachtsman witness thought it was carrying out a sea search only a short time before, is the one thing that we experienced SH operators could never work out. Gp. Captain Pete Crawford couldn't, either. As you will know, he wrote that in his part of the accident report.
One possible scenario is a runaway up of an engine, caused by a DECU fault. I'm not saying it happened, but it
is possible. I've suffered such a failure myself, albeit not on a Chinook. A colleague of that time had a similar problem some time before, on the same aircraft type. After both events, the manufacturer could not reproduce the faults. The faults were perhaps not reproduced because it was not a recognised failure mode. Afterwards I asked to practice the failure in the simulator that we used for recurrent pilot training. It wasn't possible because it wasn't programmable - the manufacturer didn't recognise the failure as a possibility so it didn't exist.