Originally Posted by
Torquetalk
Airplanecrazy,
Gullibell is sure to be right.
As a point of interest, the FMS sums all available sources to determine ppps, and tells you when it doesn‘t have a reliable determination. No or poor DME signal or a discrepancy means the FMS will disregard the unreliable source. No issue.
What might have helped him was regular real IR training and a greater willingness to use the automatics to get him out of trouble once he lost reference. Not pressing on and chomping it whilst scud running, with limited visibility, in a rising ground environment, would have avoided the accident altogether.
Thanks for your reply. I have reviewed the FMS extraction report again and I still suspect that the FMS is using the wrong position. Either the authors of the report incorrectly decoded the position information, the FMS is confused, or I am confused. The "Active From Waypoint" recorded at 17:37:43 is 34.25080271n 118.7603827w, and that is over 15nm from the actual position at that time of 34.250610n 118.450834w. Furthermore, the aircraft never comes closer than 7nm to that waypoint.
I certainly defer to your experience on whether that possible discrepancy could have had any influence on the outcome. I was hypothesizing that when the pilot entered the steep left turn about 30 seconds before the crash, that something distracted him from watching the primary flight instruments. I was wondering if problems with the NAV radios could have been that distraction, but it sounds like you think that is unlikely. I guess we will see what the NTSB thinks in a couple of weeks. I really appreciate your time!