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By: - 31st December 2010 at 12:33 Permalink - Edited 1st January 1970 at 01:00
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!
By: - 31st December 2010 at 15:12 Permalink - Edited 1st January 1970 at 01:00
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?
By: - 31st December 2010 at 20:07 Permalink - Edited 1st January 1970 at 01:00
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.
By: - 31st December 2010 at 20:25 Permalink - Edited 1st January 1970 at 01:00
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!
By: - 31st December 2010 at 23:43 Permalink - Edited 1st January 1970 at 01:00
slippy runway and dodgy reverse thrust..... could have been alot worse.
By: - 1st January 2011 at 12:37 Permalink - Edited 1st January 1970 at 01:00
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
By: - 1st January 2011 at 13:39 Permalink - Edited 1st January 1970 at 01:00
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.
By: - 1st January 2011 at 14:18 Permalink - Edited 1st January 1970 at 01:00
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.
By: - 1st January 2011 at 14:25 Permalink - Edited 1st January 1970 at 01:00
We already know all that, nJayM, all we're doing is discussing it. Nothing wrong with that, this is a discussion forum after all.
By: - 1st January 2011 at 14:42 Permalink - Edited 1st January 1970 at 01:00
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
By: - 1st January 2011 at 14:55 Permalink - Edited 1st January 1970 at 01:00
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
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."
By: - 1st January 2011 at 18:55 Permalink - Edited 1st January 1970 at 01:00
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. :D
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.
By: - 1st January 2011 at 21:30 Permalink - Edited 1st January 1970 at 01:00
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.
By: - 2nd January 2011 at 00:02 Permalink - Edited 1st January 1970 at 01:00
Runway length may be a contributory factor as in fact it is given as 6299 feet in URL http://www.theairdb.com/airport/JAC.htmlThere 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!
Posts: 24
By: gpew - 31st December 2010 at 10:14
Passenger Video: Odd things appear to be happening with the spoilers and thrust reversers as this American Airlines Boeing 757 runs off the runway at Jackson Hole, Wyoming, in snow.
http://www.youtube.com/watch?v=blFw4Y1dtps
avweb story, here:
http://www.avweb.com/avwebflash/news/757_american_airlines_jackson_hole_2253_snow_runway_overrun_video_landing_203883-1.html