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Old 9th Jan 2010, 11:21
  #366 (permalink)  
Zeffy
 
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Rwy 12 threshold elevation is 8'; rwy 30 is 17'. Of course, the threshold elevations by themselves don't describe any undulations along the length of the pavement.

If the pilot cannot see or perhaps comprehend where the touchdown zone is, nor perhaps see the PAPI (were they working / installed) then the HUD visual mode might be little more than a distraction. Technology is a wonderful thing, but most systems have limits, even pitfalls.
IMHO (and experience with HUD) it could be quite feasible that if the pilot was using HUD he was concentrating on maintaining a reasonable flight path in the turbulent tailwind conditions that he overlooked the GS reference ‘sliding’ down the runway well beyond a sensible touchdown point.
I don't recall any NOTAMs concerning the PAPI servicability; I guess we'll find out soon enough

Tournament level proficiency with HUD does require practice. However, the GS reference line, the FPV and the airspeed deviation cue ("worm/nail" whatever you happen to call it) are pretty basic to HUD operation.

And if the 3.0-deg reference line is "sliding" toward the far end of the runway while a pilot is tunnel-visioned on keeping the FPV on the TDZ, the airspeed deviation cue will be very, very hard to miss.

On a normal HUD approach, pilots typically make corrections for tiniest airspeed deviations shown by the airspeed worm -- i.e., one knot IAS.

As other posters have noted, the fact that the initial touchdown occurred 4000+ from the threshold at Vref would seem to indicate that there was an abundance of energy back at the threshold -- too high, too fast or both.

Far from being a distraction, a HUD will vividly underscore the airplane's energy state referenced directly to the runway.

These pilots were hardly low-time or new to the B737.

It will be interesting to learn the rest of the story as the investigators complete their work.

Last edited by Zeffy; 9th Jan 2010 at 13:49. Reason: grammar
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