Originally Posted by
dalek
It is without doubt the TANS was functioning until impact.
It certainly is not. The internal battery was allowing storage of incoming data but at the 26 (or 32 sec point before impact, depending on which document you read), the power switch was moved to the off position and NAV display and all other functions were lost.
If that is the way it works, then what conclusion should we draw factoring in on what you suggest about care used on inputting time on startup, the switch position after the crash, and the 26+ seconds time difference?
Surely the most likely scenario is that they turned it off 26+ seconds before the crash.
But why?
Looking at the Analysis of Available Data report, this places the switchoff at shortly before they should have reached waypoint change. Have I read that right?
I don't think that they would have had trouble controlling the aircraft at that point - they would have had other more important things to worry about than the TANS in that case.
Most likely they didn't believe what it was telling them.
And why would that be? Surely because it was telling them they were nowhere near where they thought they were.
If my reasoning is correct, then this suggests things had gone badly wrong before waypoint change.
Still loads of ifs and maybes here. Apologies for the ramble.
TN