757 Overrun Video Raises Questions

Runway length may be a contributory factor as in fact it is given as 6299 feet in URL http://www.theairdb.com/airport/JAC.html

There may have been some additional technical/operational problems on or just prior to touchdown.

The runway length wouldn’t have made the thrust reverse partially activate, then close, then open properly. There’s no may about that, something wasn’t right!

The pprune thread covers almost all possibilities nJayM. I daresay that an airport of that length at that elevation with an icy runway and all the other factors thrown in does not leave any room for complacency, misjudgment or technical faults.

Runway length may be a contributory factor though ….

If Ray Bishop, director of the Jackson Hole Airport, is accurate in being quoted saying “The airport’s only runway is 6,400 feet long, which is a little shorter than normal for airports handling commercial flights. Another airplane went off the end of the runway last month, and such events happen periodically there.”

Runway length may be a contributory factor as in fact it is given as 6299 feet in URL http://www.theairdb.com/airport/JAC.html

There may have been some additional technical/operational problems on or just prior to touchdown.

If by any chance we are still around then :diablo:, the accident docket will be found here: http://www.ntsb.gov/dockets/foia_fri-dockets.htm

That is the problem, accident reports take so long to come out that it is usually long forgotten.

I couldn’t agree more – The Press eat companies and people for breakfast

Discussion of known facts and various scenarios is fine considering that the press can come up with wild speculation from time to time. Not to mention other forums that present their full accident report on the same day. I think that most of the time we are well within limits here. 😀

Hi 27vet
I couldn’t agree more – The Press eat companies and people for breakfast. Most of it is unverified sensationalist journalism.
It destroys good companies, people and in some cases countries.

Discussion of known facts and various scenarios is fine considering that the press can come up with wild speculation from time to time. Not to mention other forums that present their full accident report on the same day. I think that most of the time we are well within limits here. 😀

From one of those URLs above, this kind of insinuation would be unacceptable here :

Glad nobody was injured, but those major pilots are dangerous.

Go look there for more.

Some early URLs on the same incident

Some early URLs on the same incident –

http://aircrewbuzz.com/2010/12/american-airlines-boeing-757-200-runway.html

http://www.expressjetpilots.com/the-pipe/showthread.php?40590-AA-757-Runway-Overrun-in-Jackson-Hole-WY

http://www.pprune.org/rumours-news/438003-american-airlines-jet-goes-off-runway-jackson-hole-wyoming.html

And quoting from the last URL above “The airport’s only runway is 6,400 feet long, which Bishop said is a little shorter than normal for airports handling commercial flights. Another airplane went off the end of the runway last month, and such events happen periodically there, he said.”

I haven’t said you cannot discuss it

We already know all that, nJayM, all we’re doing is discussing it. Nothing wrong with that, this is a discussion forum after all.

Hi PMN
I haven’t said you cannot discuss it, just pointing out that there will be a conclusive and accurate investigative report which will pull all facts together and reveal the full ‘story’.
Please see my mod to the last sentence of my post above purely to suit you

We already know all that, nJayM, all we’re doing is discussing it. Nothing wrong with that, this is a discussion forum after all.

CVR, OVR, Met and runway conditions,Tower transcripts & visuals, should reveal facts

The video is hardly conclusive (limitations in visibility from window) and the commentary says so in the second stage.
CVR, OVR, Met and actual runway conditions,Tower transcripts & visuals, should reveal facts along with engineering reports after inspection of the aircraft.
The Captain and First Officer should be able to add the conclusive statements to what they were actually presented with in the cockpit.
I’d rather wait for official findings and since no one was hurt it is at least not an unhappy ending.

Thrust reverse never actually stops the aircraft, in fact even when used heavily it still doesn’t provide anything like the stopping capability of the brakes (bearing in mind only bypass air is reversed on high bypass engines and because it’s redirected it isn’t massively efficient). Braking may well be impaired by certain runway conditions but nonetheless the aircraft still has to be able to stop without using reverse. It can obviously help in certain conditions but it isn’t factored into the stopping distance of the aircraft.

Either way it will be interesting to find out who gets the finger pointed at them.

Incident looks a lot like that Lufhansa A320 at Warsaw many years ago.

In that instance the runway was so slippery from snow and ice that the landing gear sensors did decide that no contact was made with the runway and the aircraft systems therefore didnot engage trustreversers and brakes.

It is true that aircraft can stop on brakes alone but in snow conditions braking may be impaired. Also when one of the wheel(sets) hits an ice spot the aircraft can start skidding very sideways. Trustreversers are not effected by the runway condition and provide a safer way to stop in a straight line.

The runway surface is not visible in the video so its not possible to comment on the braking conditions.

just my 3 cents

rgds
EC

slippy runway and dodgy reverse thrust….. could have been alot worse.

This is for the B767, which should be the same as the B757:

Spoiler Speedbrake Operation
The speedbrakes are controlled by the speedbrake lever located on the control
stand. The speedbrake lever has three marked positions:
• DOWN
• ARMED
• UP
The speedbrake lever can be placed in intermediate positions between ARMED and
UP.
In the ARMED position, when the landing gear is fully on the ground (not tilted)
and the thrust levers are at idle, the speedbrake lever is driven aft to the UP
position and the spoiler panels are fully extended.
On the ground when either reverse thrust lever is moved to the reverse idle detent,
the speedbrake lever is driven to the up position and the spoiler panels are fully
extended. The speedbrake lever does not need to be in the ARMED position.

Why would it open an inch or two on touchdown only to close and then not fully deploy for 30 seconds?

Because something’s wrong, it shouldn’t do that at all! Many landings don’t use anything beyond idle reverse (where the reverse mechanism is engaged but the engine remains at idle), but even then the reverse mechanism would usually be activated around the time the main gear hits and stay active until the aircraft slows to around (I believe) 60kts. I don’t know where the fault lies but something was very much not right about this landing!

You can’t actually see the spoilers, the leading edge devices are deployed, which is normal during the slowing down of the aircraft down in the approach phase.

Aren’t the spoilers supposed to be armed or is that only on older types? The action of the left engines reverser is really abnormal. Why would it open an inch or two on touchdown only to close and then not fully deploy for 30 seconds?

It certainly doesn’t seem normal, but thrust reverse is only there to assist in slowing the aircraft down. That YouTube video almost makes it sound like reverse thrust is the main way to stop a large passenger aircraft, which absolutely isn’t the case. In fact for an aircraft to be certified to land at an airport it has to be able to stop safely without using anything but idle reverse in all conditions, so even though there’s a clear delay in the operation of reverse thrust that alone shouldn’t cause the aircraft to overrun. It’s difficult to tell but it doesn’t really appear that the aircraft is braking all that hard; you really know about it when the anchors are slammed on, and that seems remarkably sedate.

I have no idea what’s wrong, but something doesn’t seem right!