The Boeing report by James Mitchell is mentioned quite often and it is a useful guide , but study it with caution as it does contain errors.....
.............perhaps the most obvious is his lack of knowledge of the geography of Northern Ireland , he thought that the Chinook could take off and travel directly to the Mull crash site at 500 feet agl/asl........only there are actually mountains in the way as posted previously and the clearance for the flight was understood to be 'not above 500 feet on the regional QNH'.........
The business of the 'mythical' right turn after waypoint change is another anomaly , Mitchell uses an initial track of 19.5 degrees true , but from the centre of Aldergrove airfield to the real position of the lighthouse is 19.8 degrees true......(he actually used a starting point of the stated position of the boundary radio call ?????.. which is wrong , as it is above the 500 foot limit for that part of the flight...when he converts this supposed 'fix' to a lat/long.it is obvious that he is unaware that VOR are aligned to magnetic north , so he plots a route from much further east than reality)..but....
When you measure from the BEL vor ,( close to the north/south runway which they departed from ), to the actual point of impact , the course is 21.23 degrees true , which passes through the point of waypoint change once that point is corrected for the GPS error and the slight offtrack to the right which they were flying......so there was no right turn...
...........but another point which keeps emerging is the unlikely 'calculated' groundspeed of 162.8 knots........Mr Mitchell states that ...........
there was a subsequent GPS position recorded, which had not yet been processed by the SuperTANS. This position shows the aircraft at N5518.64, W00547.78, which is approximately 190 feet from the originally
recorded position, at a bearing of 21 degrees. The same paragraph states that the GPS receiver updates its position once per second, and transmits that data five times per second to the SuperTANS. The SuperTANS continuously reads this input data, but only processes it once per second. Consequently, it can be surmised that the difference between the two positions is separated by 1 second,
..which gives 190 feet per second.............around 112 knots............very plausible as they may have hit the ground already..............
..but rather than pointing out this obvious speed indication , he tries to create some values using triangles of velocity........first using other recorded facts from the Racal report , and then by assuming that the aircraft/wreckage turned partly downwind to reach his 162.8 knots figure......
Using this airspeed, the evidence of the tire tracks, and the wind speed, an aircraft groundspeed just prior to impact of 162.8kt is arrived at, with an aircraft heading of 17 degrees T or 24.8 degrees M.
This calculated groundspeed value is consistent with the value of groundspeed derived from the last displayed values of distance to go and time to go values that were recovered from the steering display. These values were 86.7nm and 32min, respectively, which results in a groundspeed of 162.6kt, i.e. very similar to the calculated value of 162.8kt,
..no it isn't/doesn't ...........he has not noticed the display has rounded up the distance , and rounded down the time , the correct values give 158 knots if continuing to Corran......the same as the average for the whole route..........
This false speed information shows up some eight times recently in this thread..............and ..........
.......goodness me......
..they all seem to be from the same person.........some one called ...
...Cazxxxxxxxxxxxxx....??????????.................