Oops! AAL 757 overshoots runway at KJAC-Added You Tube video


#1

"JACKSON, Wyo. – An American Airlines jet went past the end of a snowy runway while landing at Wyoming’s Jackson Hole Airport on Wednesday, but no one was injured and the plane was not damaged, officials said.

Read more: foxnews.com/us/2010/12/29/pa … z19YDXzvro"

flightaware.com/live/flight/AAL2 … /KORD/KJAC

Updated video link: https://www.youtube.com/watch?v=blFw4Y1dtps)

Paging Mr. Patroni.


#2

video removed by user :frowning:


#3

Too bad. It was a good view of the delay of the thrust reverser deployment. After rolling out a good bit without slowing much, the TRs finally fully deployed with a fury. The snow was a flyin and the passengers were quite concerned.


#4

Think the airline wanted it censored???


#5

I don’t know about the 757 but a lot of airplanes do not let the reversers deploy until the weight on wheels “WOW” squat switch on the main landing gear has done it’s thing.
Picture an electrical diagram where a bunch switches are in series. Both throttles must be no higher than idle, both squat switches engaged and on some airplanes an armed switch in the reverse mode then you can get power to the mechanism when you pull up on the T/R handles. Most aircraft also have a lock out solenoid that won’t let you physically pull up on the handles until those switches are all closed.


#6

That or the TSA didn’t like photographers within 8 miles of the airport. :wink:


#7

There’s a video available here: https://www.youtube.com/watch?v=blFw4Y1dtps)


#8

[quote=“rw812”]
There’s a video available here: https://www.youtube.com/watch?v=blFw4Y1dtps)

Wow no spoilers either? What were the guys up front thinking, other than wishing they could go skiing?[/quote]


#9

[quote=“QuickBurn”]

Wow no spoilers either? What were the guys up front thinking, other than wishing they could go skiing?

I have no knowledge of the systems om the 757 but I’d gather that they deploy on touchdown automatically[/quote]


#10

You jet pilots would know better than I, but the plane has to be capable of stopping before the end of the runway without reverse thrust, or you can’t land there, right? So you can’t blame it on mechanical failure. Pilot error, poor braking action? The tapes will tell.


#11

I have no knowledge of the systems om the 757 but I’d gather that they deploy on touchdown automatically

If the pilots want them to, right?


#12

I am an airport guy, not a jet pilot, but I don’t think pilots have to take into account reverser failure when computing landing distance. If so I would doubt a 757 could ever operate on a 6300 ft runway as I bet their brake only stopping distance is much greater.

From the video, not seeing the spoilers deploy, and seeing the reversers open slightly, then close, then open fully, I would suspect some kind of mechancal issue.


#13

Checked it out. Far 25.109 (f) (1) Thrust reversers are NOT to be considered when calculating landing distance. So if you don’t have enough runway to safely stop without reverse thrust you can’t land there. So the fact that the reversers may not have worked properly here should not be the reason that the plane went off the end since it should have been able to stop safely without reverse thrust. If it could only stop safely with the use of reverse thrust, then it was illegal to land there.

I would bet that American Airlines would never let its 757s land at Jackson Hole in violation of the Far. I am sure that it could stop in the distance of that runway without reverse thrust provided everything else was done right.


#14

According to a B757 study guide, “Braking provides the primary stopping force followed by spoilers and reverse thrust.” This is in reference to aborted take-offs. I couldn’t find anything that clearly stated that brakes were the primary method of stopping after landing. There was something about brakes (autobrakes) not being used until the aircraft was below 85 knots so it would seem that the reversers need to be used to slow the aircraft down to 85 knots before the brakes kick in.

I don’t think this goes against FAR 25.109 (f) (1) because wouldn’t dispatch consider the time to (a) slow the aircraft down to 85 kts plus (b) the distance it takes for the brakes to stop the aircraft to make sure the total of (a) and (b) isn’t longer than the runway length. I know what I’m trying to say - not sure if it came out that way. :slight_smile:


#15

Autobrakes on landing: Applied when both throttles at idle and wheels spun up.
Autobrakes on RTO (rejected takeoff): Maximum braking with both throttles at idle, speed above 85 kts and wheels spun up.
Me: below 85 the autobrakes go to low brake or go off.

Speedbrakes on landing; required by checklist (the study guide is from Delta but probably the same procedure as American)
Extend when wheels on ground and throttles at idle.

My speculation: When the thrust reverser did not deploy the landing pilot may have pushed the piggybacks back to the stowed position and inadvertently pushed one or both throttles slightly above idle, pulled the throttles back to idle then redeployed the T/R. But in doing so the autobrakes and speedbrakes would have been unarmed (dis-armed?).
Or, on an icy runway they did not get wheel spin up as quick as normal.

FAR 121 requires the computed full stop landing distance to be no more than 60% of the runway length. Wet or slippery conditions require the runway length to be no less than 115% of the above calculation. (hows that for paraphrasing?)

You guys are correct, Part 25 jet airplanes do not use thrust reverse in the calculations. Brakes are by far the most effective at stopping the airplane.


#16

That’s good, John.
And I think dis-armed is the correct one. :stuck_out_tongue: :wink:


#17

The 757 has some of the best runway performance numbers for airliners.
It is a pilots airplane.

I’m betting on an inaccurate or absent breaking action report being the root cause. Setting up a chain of minor events as described by John ending up with the bird going a bit long.

Jackson doesn’t have measuring equipment and they rely on pi-reps from preceding aircraft.


#18

That is hard to believe for me, as even little ole MCW has a Vericom for friction testing. I can not believe the FAA would allow Jackson to have such large aircraft operating on that size runway, in the winter conditions they have, without some kind of friciton measuring equipment.


#19

I was just there, braking was reported fair by the Airbus infront of me. I had poor braking. They shut it down for 40 mins plowed & swept. Never got braking action measurements prior to departure, just a pirep from a 757 that landed.
There was a Yellow Saab running around talking with ground corrdinating the sweeping but there was never a measured index reported.

I am still leaning to no testing equip, prove me wrong and I’ll admit it.


#20

Sorry if you misunderstood, I am not calling you wrong. I have checked the NOTAMs numerous times and have not seen any reported MU readings. I just can’t believe that FAA would allow them to operate without at least something.

Now on the other hand, the FAA seems to be shifting their stance on issuing MU NOTAMS. They have found that most pilots don’t understand what an MU reading is or how to use them, but at the same time giving reports of Good, Fair, etc. is too subjective to both the issuer and the reader. I predict in the next winter season or two (perhaps sooner after this incident), there will be new guidance to airports for reporting braking actions.

After watching the video numerous times, I would suspect as its been mentioned, that this incident was a result of numerous small issues. It was probably a combination of reduced braking actions and delayed application of reverse thrust and spoilers. There is also the possibility they landed at a higher than normal speed, although they did touchdown in the right spot, if a little sooner.