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Hopefully someone will post something better shortly, in the meantime do I see the LH mains tucked up where they shouldn't be?:
https://cimg9.ibsrv.net/gimg/pprune....47e3c07993.png |
KIAH once again accepting arrivals on 27 so accident MAX must have been moved. NOTAM closing runway 27 until 3/23 has been cancelled.
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Drifting to the MAX…
“With about 1,000 ft and 500 ft of runway remaining the airplane ground speeds were about 72 kts and 57 kts respectively. The right turn to exit the runway was initiated at about 39 kts groundspeed and the aircraft departed the end of the paved surface at about 22 kts.” NTSB Aviation Investigation Preliminary Report - N27290, UAL2477 |
I wonder how the ground speed is determined. If it is from the tires then as the slide begins the ground speed will only be in alignment with the fuselage and not represent the true velocity of the aircraft. By way of example - if the plane is sliding directly sideways the tires will not rotate regardless of the slide speed.
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Originally Posted by MechEngr
(Post 11629912)
I wonder how the ground speed is determined. If it is from the tires then as the slide begins the ground speed will only be in alignment with the fuselage and not represent the true velocity of the aircraft. By way of example - if the plane is sliding directly sideways the tires will not rotate regardless of the slide speed.
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Originally Posted by OldnGrounded
(Post 11629924)
ADS-B ground speed is GPS-derived.
Correct. |
I see - there is a ground speed graph that appears to be from the DFDR as well as the ADS-B data.
Comparing the two would allow finding out when the slide started, but the graph is too compressed to make that easy. |
It seems that it was not so much UA2477 that suffered a runway excursion, but it was more the runway and grass borders which suffered this excursion upon them.
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Autobrake 1 and stowing the speedbrakes (and thus cancelling autobrake) early into the landing roll, combined with idle reverse on a contaminated runway...
What were they thinking will stop them, aerodynamic drag? |
Originally Posted by BFSGrad
(Post 11611762)
Originally Posted by FlyingStone
(Post 11630194)
Autobrake 1 and stowing the speedbrakes (and thus cancelling autobrake) early into the landing roll, combined with idle reverse on a contaminated runway...
What were they thinking will stop them, aerodynamic drag? Ditto re stowing speedbrakes and idle reverse. Where's that come from? No shortage of contaminated RT though, as usual. "We're rolling the trucks en route" indeed! Let alone readbacks from most of the other traffic, in a situation where punctilous readbacks are even more essential than usual. |
Originally Posted by meleagertoo
(Post 11630277)
Where's there any suggestion the runway was contaminated? The METAR doesn't mention anything remotely suggesting that is possible and the videos show it isn't even raining.
Ditto re stowing speedbrakes and idle reverse. Where's that come from? No shortage of contaminated RT though, as usual. "We're rolling the trucks en route" indeed! Let alone readbacks from most of the other traffic, in a situation where punctilous readbacks are even more essential than usual. |
Originally Posted by meleagertoo
(Post 11630277)
Ditto re stowing speedbrakes and idle reverse. Where's that come from?
The speed brakes extended normally, and the thrust reversers were deployed to idle reverse thrust. The captain said that, shortly after touchdown, he retracted the speedbrakes by the action of moving the speedbrake lever to its down and locked position, which disabled the autobrakes. He did not “slow too much initially” because the runway appeared dry, he wanted to expedite their time on the runway, and because he preferred decelerating gradually for passenger comfort. |
for passenger comfort
I wonder how many incidents / accidents identify 'for passenger comfort' as a contributory factor ?
If the RCC was notified as 3/3/3, then "if unfamiliar with the runway, probably best to treat it as advertised" would be very good advice - FAA view. EASA mandates the use of notified RCC in the before landing performance calculations. |
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