Racal Report(s)
In view of some of the comments made last week about Waypoint changes over land etc, I decided to read the RACAL report(s) again to see if there was anything to support this claim. I got as far as:
1.1.5 The data extracted is that pertaining to the time of last powerdown of the system. The equipment is not designed to provide "historic" data, but attention has been paid to analysis of data which may indicate the situation at a time earlier in flight.
Just what part of "not" and "may", did Wratten and Day not understand.
By presenting this simulation to the HOL as established fact they were telling blatant lies. The only other explanation is that they gave their evidence without ever reading these reports.
The report shows the TANS to be working to a very high spec approaching the Mull. Seven satellites in solution and a doppler within 330 m of the GPS position. Overall accuracy would have been around 10 m, maybe even better.
So the crew approached the Mull in VMC, visibility one mile or more with equipment giving them precise ranging information. A Chinook contributor I have recently pm'd thinks Holbrooks initial estimate of speed was wrong but one of 120 - 130 IAS was more likely. This ties in with the RACAL estimate of 127.5 TAS 151 GS at impact. So just where was negligence at this point?
If Wratten accepts VMC, sensible speed at WP change, and bases negligence on poor low level abort proceedure, the simulation throws up other anomalies.
If the crew have over a mile visibility and the coastline is clearly visible, they have well over 20 secs to do something. Their TANS is giving them precise ranging. Even if the visibility to the left is poor, why not slow down and come right about? With the icing limitations, an abort is not the best option.
If the simulation is to be believed the crew made a manual change of Waypoint. I never did that until I had identified the Waypoint before. I expect this crew did the same. Having done this, one of the crew switched the display off and if the crew were still in full control of the aircraft, they elected to coast in using DR navigation??
I could go on. This simulation poses more questions than it gives answers.
Final point: Cable gives impact speeds of IAS 150 GS of 174. He bases this, I believe, on debris pattern. The simulation gives TAS 127.5 GS 151. That is a big discrepancy.
If Cable is close to correct then a anaysis worked back from false data at impact is clearly bo**ocks.