UA2477 suffers runway excursion at KIAH

[Boeing Junkie]

737-Max 8 tail # N27290 currently sitting a ditch at KIAH

https://twitter.com/RenGanner/status/1766106367834607810

[mkenig]

Reports are left gear ran onto soft grass adjacent/turning onto last taxiway. Not a ditch, not overrun excursion. Taxi issue in heavy rain and fog?

[BFSGrad]

Landed runway 27.

KIAH 081353Z 19005KT 1 1/2SM BR BKN008 OVC018 23/22 A2971 RMK AO2 SFC VIS 2 1/2 SLP059 T02280217

[procede]

Live ATC: https://www.youtube.com/watch?v=ryS6w9b6OlE

[BFSGrad]

More complete pertinent ATC audio in the version:

United Flight Veers Off Runway Landing in Houston

[DIBO]

A/C "Can we roll it all the way to the end?"
TWR "Keep your speed up"
Then initiating a 90° turn onto SC twy at a GS of 30-ish kts, on a wet/damp surface...

[Hueymeister]

Yup, that’ll do it.

[BFSGrad]

Makes you wonder why UAL was unable to make the high speed (SF) at the 8,000 ft point. Suspect ATC was planning an SF exit for spacing with the next arrival (1383), thus the “keep your speed up.”

Any bets on whether the CVR was vaporized? At least the FDR will tell the tale.

[MechEngr]

Ran when parked.
No low ballers.
We know what we have.

Photos on news show considerable turf damage from going sideways off the taxiway. I expect the groundskeeper will demand United replace the divot.

[ozbiggles]

Ran when parked.
No low ballers.
We know what we have.

Photos on news show considerable turf damage from going sideways off the taxiway. I expect the groundskeeper will demand United replace the divot.

Good luck with that, how long did it take them to replace a guitar?

[BoeingDriver99]

Any motorcyclist will tell you; the painted bits are slippery when wet. Avoid at all costs. And the piano keys make for a hell of a lot of paint for slipping on.

[Ripper3785]

ABC13 first heard the Houston Fire Department reporting the incident on radio traffic around 8 a.m. HFD first reported an "alert two," which means a plane in the air has had some kind of incident that requires emergency response. Within minutes, HFD escalated it to an "alert three," which means a plane has had an incident on the ground.

I assume this is just bad info or someone made a mistaken radio call re:alert level. When i read it I was reminded of the stuck rudder from cold soaked servo of another MAX 8.

[BraceBrace]

Any motorcyclist will tell you; the painted bits are slippery when wet. Avoid at all costs. And the piano keys make for a hell of a lot of paint for slipping on.

On the topic of slippery paint, a bigger "threat" is lack of knowledge on the "no weight on the nosewheel" situation. Widebody people generally are aware, but it's less known with 737 classic and NG skippers as FOs have less taxi experience prior upgrade. It's a remark that is commonly made when upgrading these FO's.

This Ryanair has already proven they can easily get it done on a dry runway as well...
https://www.youtube.com/watch?v=iOYMzu4Avjw

(ok, Ryanair folks... I know the purple video is out there :-))

Anyway, not saying this is what happened here. Lots is possible.

[Flch250]

Am I mistaken? You are on the runway and it is yours. What is this may we stuff?

[BoeingDriver99]

Purple video??? Spill the beans!

[Chiefttp]

Purple Video?
Are you referring to the recent FedEx MD-11 taxiing video? It was a MX taxi not pilots at the controls.note the gear pin flag on the left main gear flapping at the end of the video
https://barandgrill.ipapilot.org/home/leaving?allowTrusted=1&target=https%3A%2F%2Fvideo.twimg.com%2Fext_tw_video%2F176327 0884494626816%2Fpu%2Fvid%2Favc1%2F320x330%2FJPNid_Q8SC9PxWyB .mp4%3Ftag%3D12

[BraceBrace]

Purple Video?
Are you referring to the recent FedEx MD-11 taxiing video? It was a MX taxi not pilots at the controls.note the gear pin flag on the left main gear flapping at the end of the video
https://barandgrill.ipapilot.org/home/leaving?allowTrusted=1&target=https%3A%2F%2Fvideo.twimg.com%2Fext_tw_video%2F176327 0884494626816%2Fpu%2Fvid%2Favc1%2F320x330%2FJPNid_Q8SC9PxWyB .mp4%3Ftag%3D12

Nice catch! Didn’t know that ... although I know pilots...

ok going too off topic now 😀

[BFSGrad]

View of the tire tracks (skid marks?) at 0:51.
KHOU 11

[Lake1952]

Is the tilt due to left main gear sinking into soft ground, a ditch or gear failure?

[Boeingdriver999]

Purple Video?
Are you referring to the recent FedEx MD-11 taxiing video? It was a MX taxi not pilots at the controls.note the gear pin flag on the left main gear flapping at the end of the video
https://barandgrill.ipapilot.org/home/leaving?allowTrusted=1&target=https%3A%2F%2Fvideo.twimg.com%2Fext_tw_video%2F176327 0884494626816%2Fpu%2Fvid%2Favc1%2F320x330%2FJPNid_Q8SC9PxWyB .mp4%3Ftag%3D12

No idea; hence the question....

If the main gear made those skid marks they must have been hauling ass.... Plus max manual braking would have given a bit of Swedish flick to the nose gear.

Nothing a UA crew couldn't accomplish in a normal day of work... if they worked

That's a joke by the way; keep your main wheels on

[First_Principal]

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.org-vbulletin/541x330/closeup_7a4d9b83d71d924b8a57de1c0e25e747e3c07993.png

[BFSGrad]

KIAH once again accepting arrivals on 27 so accident MAX must have been moved. NOTAM closing runway 27 until 3/23 has been cancelled.

[BFSGrad]

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 (https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193898/pdf)

[MechEngr]

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.

[OldnGrounded]

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.

I believe ADS-B ground speed is GPS-derived.

[B2N2]

ADS-B ground speed is GPS-derived.


Correct.

[MechEngr]

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.

[jolihokistix]

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.

[FlyingStone]

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?

[meleagertoo]

More complete pertinent ATC audio in the version:

United Flight Veers Off Runway Landing in Houston (https://youtu.be/0nToERYvYmQ)

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?

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.

[jetpig32]

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.

RCC was at 3/3/3 due to “slippery when wet” notam. Per FAA AC, if any portion of the runway fails friction RCC 5 when wet, they notam whole thing 3/3/3. Typically due to rubberized deposits. 27 in Kiah is heavily a landing runway, where 9 not so much. Either way, if unfamiliar with the runway, probably best to treat it as advertised.

[FlyingStone]

Ditto re stowing speedbrakes and idle reverse. Where's that come from?

From the report:

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.

[PEI_3721]

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.