Chinook - Still Hitting Back 3 (Merged)

[ShyTorque]

Walter,

I'm going to try one last time to explain a few things that you seem to have misunderstood. What you have probably seen at airshows is a demonstration of the limits of helicopter physical manoeuvrability, not much more than that.

You should understand that this is very different to how a helicopter is flown on an operation, especially in bad weather, more especially when at relatively high weights and on a passenger carrying flight. Passengers are often apprehensive, even in straight and level flight and crews are trained to fly accordingly, sympathetic to the operational situation and most definitely not merely trying to make a lot of noise and please the crowd, such as is allowed at airshows, by specially trained display crews.

An approach to a landing site begins some way back when the aircraft is flown at cruise speed towards an initial point, somewhere obvious to find, and from where the gradually decelerating landing approach can begin (this is done by eyeball, not by using a DME. DME is not accurate enough). The helicopter is slowed down from cruise speed to something like 60 to 90 kts, to give the crew time to assimilate local features and to allow themselves sufficient orientation, and they would then probably follow a lead-in feature, flying from a 50,000 map, using what is known as the "map to ground" technique. Crew are trained to use something like a tree line, a ridge line, a valley, a track, railway line or any other useful feature; each locality having it's own unique scenario. In bad weather such as was apparent in this case, the aircraft would be flown more slowly, just as if you were driving your car in poor weather and were looking for a house address.

However, this helicopter, after a reported time at quite a low speed, (yachtsman's evidence) subsequently accelerated under high power, to a speed equal or higher than the normal cruise speed, then hit the ground in a slight climb, with the yaw pedals (helicopters don't have "rudders") deflected to almost full travel.

During any emergency abort/climb, (I've done quite a few in my time) a helicopter's yaw pedals would normally be deflected only enough to keep the aircraft in balanced flight; i.e. with the balance ball in the middle, as speed was traded for climb performance, in addition to use of full power. This would not be anywhere near full deflection, such as was strangely apparent in this accident.

It was the very high impact speed, coupled with the very large deflection of the yaw pedals, that led the station commander RAF Odiham to make a statement to the effect of (I don't now have access to his written report) that the aircraft hit the ground in a configuration that he couldn't understand.

I agree with him, so does any experienced SH pilot. Why it was suddenly in this high speed, cross-controlled configuration, in that location, after slowing down approaching the coastline, is where the trail goes completely cold. Everything else is conjecture or opinion.

However, if the aircraft had developed an emergency of any sort, the crewman would leave his vulnerable position by the door (where he would be restrained only by a belt harness) and move forward to assist the pilots and to get himself into a more secure personal position on the jumpseat. There would be every reason for him not to remain by the door. Bearing in mind the BOI found evidence of the co-pilot's comms box selected to its "emergency" position (i.e. some sort of comms failure, possibly nothing more, but maybe also something more serious, such as an electrical problem). Also, only one "row" selection of the transponder was just one digit away from 7, which would have completed a selection of 7700, the full emergency code to alert ATC units, it is possible they had a further emergency.

We will never know.