Waypoint Changes
WK,
As an engineer I have tried to avoid dipping into the operating issues, but surely if you look at the BOI track analysis 035(M) had been the course all the way from Northern Ireland, so it is not surprising that it was set on the HSI.
Please read again the section from the BOI on "Navigation
Navigation Techniques.
At the time of impact, the SuperTANS was selected to ‘Tac Steer’ to WP B, Corran, on the western end of the Great Glen. This WP had been selected at a point on track, 1.75 km before the impact point. Although the Board were unable to establish the SuperTANS selection prior to this WP change, it is considered most likely that a ‘Tac Steer’ to WP A was selected, as this was the first WP programmed into the SuperTANS route and the first turning point on the crew's plan. This selection would have provided the crew with accurate distance to run and bearing information to the Mull of Kintyre lighthouse, up to the point of WP change.
Regardless of the WP selected prior to the WP change, once the change had been made, the crew were dependent upon comparing SuperTANS range and bearing information to Corran, approximately 87 miles to the north, with range and bearing information from their maps, to determine their current position. More importantly, this would also have deprived them of immediately apparent range and bearing information from the landmass of the Mull of Kintyre. The Board determined that the WP change would have produced a required heading change in the order of 14 degrees to port. The decision to change the WP selection to WP B would have been inappropriate if the crew had intended to continue to route to WP A or to a landfall on the Mull of Kintyre, without first having established visual contact with the WP or land.
However, if this plan had changed, and the new intention was to route initially direct to Corran, the selection of WP B would have been appropriate, providing that they had taken action to avoid confliction with the Mull of Kintyre. The Board therefore concluded that navigation technique was not a factor in the accident.
Now if, as you contend, the crew planned to land on the field by the lighthouse, why did they change waypoints. They had a VFR flight plan and were VMC when they changed waypoints - at that point as current MOD operators have pointed out they would have expected an immediate course change, indeed geography would have dictated this as well - after the WP change the HSI would, I assume, have been showing the demanded course to WP B, but, of course, they continued on essentially the same course. Why would they take such an inconsistent set of actions?
In a previous post you said that a witness at one of the Inquiries had said that the odds of a control jam in two channels were "billions to one" - please tell me who said this as I would like to see the basis for his calculations, especially given the AAIB comments on this area. They certainly do not dismiss a major control jam as "nonsense" - indeed they accept that it could not be ruled out - what do you base your judgement on?
Like you I do not know what happened, but I do not believe that after the WP change the crew had any intention to overfly the Mull, and this has, for me, always been a major non sequitur in the BOI's finding that they had set an inappropriate ROC to clear the Mull. Were they distracted, did they suffer a major control restriction and make a last moment and obviously unsuccesssful attempt to climb over the Mull because they had no choice? I do not know, you do not know - the Reviewing Officers do not know, and even John Purdey does not know, and you cannot find someone guilty of Gross Negligence (effectively manslaughter in this case) on the basis of any of the evidence to the BOI or even the BOI's findings. For example, the join where the Air Marshalls decided to change the direction of the Stn Cdrs review of the BOI is obvious for all to see.
The "advantage" of having the cause of this accident as down to the pilots becomes more obvious with every bit of FOI material that we see, and if the AMs had left the cause of the accident as even a balance of probablities of pilot error they would probably have got away with their unjust verdict. As it is the actions of the AMs and MOD have ensured that Pandora's box is well and truly opened, and it questions the whole issue of the RAF's introduction to service of the Chinook Mk2 as well as what happened to ZD 576. The lack of a just and even supportable verdict is what all of this is about, and it always has been, for "we will never know".
JB