PPRuNe Forums - View Single Post - BREAKING NEWS: airliner missing within Egyptian FIR
Old 4th Nov 2015, 06:27
  #790 (permalink)  
RYFQB
 
Join Date: Feb 2015
Location: NO
Posts: 38
@ peekay4: I was curious about how accurate the GPS derived VS would be, so I made an experiment. In this .cvs you'll find a few new columns:

- c_alt contains the change in altitude from vertical speed over time
- n_alt contains the new altitude calculated from previous n_alt + c_alt
- d_alt contains difference between (baro) altitude and n_alt
- vs_alt contains altitude calculated from last trusted altitude and GPS VS after upset

The difference before upset is never more than a few tens of feet, and at the moment things start to happen (t=793.671) the difference is 19.5 feet. So for as long as the GPS precision remains good (which is not all the way to the end), I think the GPS VS and consequently calculated altitude is fairly trustworthy - at least compared to the old data.

My apologies to the folks who are not of the FR24 persuasion.


Last edited by RYFQB; 5th Nov 2015 at 23:47. Reason: Added a map with some of the points, like where GPS precision deteriorated. Coords of last points (p0) should not be trusted.
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