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-   -   Fedex plane crash (jpn news) (https://www.revscene.net/forums/569230-fedex-plane-crash-jpn-news.html)

no_mercy 03-25-2009 03:30 PM

Quote:

Originally Posted by Rich Sandor (Post 6344921)
Windshear means "wind changing direction & intensity very suddenly"

If you have a 47knots headwind, and you are in the flare, about to touch down, then all of a sudden, the 47 knot headwind veers to a 47 knot tailwind, you'd suddenly lost 94knots of airspeed.

If your approach speed is 155knots, with an added 20knots for headwind, you'll be flying 175knots. Your stall speed is 80knots.

So you're doing 175knots, and all of a sudden the wind veers 180degrees and you loose 94knots of headwind, now your airspeed is suddenly RIGHT AT STALL SPEED.

What do you think is going to happen?

PLANE FALL DOWN GO CRASH.

It's actually pretty simple.

The nose being down in the video is all part of what happens after a plane stalls. Either the nose drops after the stall, or the pilot pushes the nose down in order to recover from the stall. Either way, the plane stalled, or was about to stall, just before touchdown, hence the nose down pitch. In that situation, pulling the nose up would be either impossible, OR, it would result in a straight down vertical drop which would more dangerous than hitting in a slightly nose down attitude but with a forward motion.

I understand how to recover from a stall as I'm a commercial student. The MD-11 is have a sensitive control when landing so it looks like after the first porpoise, the crew may have over corrected for the go around and pulled too much up and then over corrected by putting too much down...

It looks awfully weird for a windshear... I'm not sure why but I feel it's something more complicated that we can't see...

Rich Sandor 03-25-2009 03:40 PM

All we can comment on is what we see in the video. What we can't see, is what the pilot's were doing and what the wind was doing, so, it's kinda pointless to speculate now, since we don't have all the information.

Hopefully the investigations will reveal exactly what went wrong, so that those of us who fly airplanes won't repeat the mistake.

no_mercy 03-25-2009 03:45 PM

and during porpoise, i would maintain my aircraft's attitude and never push down... if i was in a stall in that case, power up and maintain attitude this low... i don't see the benefits of pointing nose down when i'm 10feet off the ground...


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