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Old 17th Sep 2011, 09:30
  #93 (permalink)  
gravity32
 
Join Date: Jan 2011
Location: Australia
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A320,
For anyone who clicks my links combined with reading your posts here, they will understand you opened this thread to gain support of pressure altimeter error operating "outside pressure altimeter calibration".
True, but I soon learned here that most of these experienced pilots agreed that there was no reason to suspect the radalt would be wrong, and therefore it must have been the pressure altitude that was wrong.

After you disclosed the speed on page 4, every single pilot on this thread concluded that the pressure altimeter was not operating outside of it's calibrated envelope.
False. Obviously it would be calibrated at the observed speed, 488 knots, at high altitude, but at 50 feet above sea level the plane couldn't be legally flown, so couldn't be test flown, so one would think it couldn't be calibrated. Can you explain how it could be calibrated at a speed far above its legal maximum speed? What grounds are there for claiming that a calibration in thin high altitude air can be applied in dense sea level air?

So let us put this into perspective.. The Radalt was operating more than 2x outside of it's tracking capability according to the data.
You have not provided any source for your claim that the manufacturer's limitation is for horizontal velocity. The plane only moves a tiny fraction of a millimeter in the time it takes for the signal to reach the ground and be reflected back. How can there be any limit to horizontal capability? One concludes this is a false claim.

For example, according to your claim that radalt tracking capability is based on vertical speed, if the aircraft were traveling at 250 knots (422 fps forward speed) with a descent rate of 320 fps (19,200 fpm), you are implying that the radalt could track this measurement because the vertical descent rate is less than 330 fps tracking capability..Pilots here will understand how absurd this notion is as the angle of descent is almost 50 degrees.
The plane was only descending at about 50 feet per second, 3000 feet per minute. I think pilots here will agree that they can safely depend on the radalt at that rate of descent and will find your discussion of an "almost 50 degree" angle irrelevant.

By the way, are you the same A320Slave who came to this site in 2008 to try to get people to agree that AA77 would not have been able to get its position reports correct if it started its flight without entering its exact position prior to moving? Did you not believe John Farmer when he provided on overlay of the radar track and the FDR track, which showed the two tracks converging after the plane had been in the air for a few minutes, and presumably in reach of DME and VOR signals?
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