Walter, I have no knowledge or experience of the Chinook of whatever mark or of its nav kit, but I think that you are suffering from a fundamental misconception about military tactical flying, be it rotary or fixed wing. So far you have encouraged us to believe that these pilots slavishly followed the DME from the wacky radio counting down until it counted them down into a hillside. Now you propose that they slavishly followed an HSI, whatever it could or could not be coupled to. As others have repeatedly pointed out the navigation of such low level sorties was, and I suspect still is, Mk1 eyeball, map, and pilot navigation (1 in 60 rule etc).
The Hercules K model was stuffed full of avionics, mostly UK made to the extent that half the aircraft's initial cost was in pounds Sterling. We had Decca map displays that purportedly told you where you were on a badly distorted roller map, providing of course you first told it where it was beforehand and were in the area of coverage. We had doppler roller map displays that consumed a fortune in charts as the Co-pilots had first to perform Origami on them and discard the excess. With the inherent drift involved it was very much advisory only in its authority.
In short you were/are responsible for knowing where you are and what is ahead, not the bloke wandering around the Mull with a backpack, not the shysters who flog dodgy kit to the MOD, not even the MOD for buying it, you are! I do not share the theory that this accident was nav based, illustrious though its proponents may be. This aircraft was a death trap, that was set when it was granted an RTS into RAF service, and was very likely sprung seconds before it killed 29 people.
Last edited by Chugalug2; 15th Dec 2010 at 21:22.