American Airlines jet goes off runway in Jackson Hole, Wyoming
Join Date: Jan 2008
Location: USA
Posts: 100
Likes: 0
Received 0 Likes
on
0 Posts
Hotel Tango wrote:
For the video, see the link at Post 174 above. It is has commentary from AVWeb.com
I see that the video (taken by one of the pax) has been removed. Perhaps some of you later posters have not had a chance to watch it. My recollection was that it indicated a positive rather than a soft landing.
Guest
Posts: n/a
Notes: 1:33, Touch. 1:34, TR gate opens, but not fully. 1:48, gate stows. 1:54, gate opens, TR deployed. 1:02, High Thrust is heard. 1:11, in the snow.
"Jesus Christ"......"Amen"......."No more the Problem, No more the problem!!"..
The 1:33-1:34 are more like 1:32.7- 1:33.5
If TR were selected prior to Untilt, (The time log would say that) There is a logic regroup, and a delay. Thrust was rejected (a/c origin) and the TR did not deploy until the gate shut, and waited for Untilt to initiate a new sequence. then up comes the thrust. I think the Boeing did what it was supposed to do. Spoilers? Tough call.
The a/c is confused. Premature action??
"Jesus Christ"......"Amen"......."No more the Problem, No more the problem!!"..
The 1:33-1:34 are more like 1:32.7- 1:33.5
If TR were selected prior to Untilt, (The time log would say that) There is a logic regroup, and a delay. Thrust was rejected (a/c origin) and the TR did not deploy until the gate shut, and waited for Untilt to initiate a new sequence. then up comes the thrust. I think the Boeing did what it was supposed to do. Spoilers? Tough call.
The a/c is confused. Premature action??
Join Date: Aug 2005
Location: fl
Posts: 2,525
Likes: 0
Received 0 Likes
on
0 Posts
The video definately shows touchdown before attempted reverser deployment. The half second skip might have caused a problem with TR deployment but manually braking and manually deploying the spoilers shouldn't have been a problem. If braking action was good as reported, if it was accurate, then reversers would not have been a big factor. Notice I'm paying more attention to my commas?
Guest
Posts: n/a
The video does not show Touchdown prior to "attempting" to deploy TRs. What it shows is the Jacket migrated aft an inch, then stopped. The attempt was prior to the open/jam, by how much is on the DFDR. If the untilt had not completed, or the switch was operating in normal sequence, the manual application could well have been prior to T/D. IMO. Without spoilers, and good braking, it was a dice roll anyway. T/Rs are not crucial, as explained, but the lack of T/R deployment in timely fashion does suggest some thing was amiss with the plan. It is not accurate to state conclusively, but if the TR system was this late, and occupied our crew elsewhere........not a good runway to get behind the a/c.
Join Date: Aug 2005
Location: fl
Posts: 2,525
Likes: 0
Received 0 Likes
on
0 Posts
I have never seen a pilot deploy thrust reversers before touchdown. Has anybody else? They won't deploy in modern aircraft if you did so what difference does it make? Why manual brakes and spoilers didn't stop the airplane is what puzzles me. Maybe the braking action wasn't as advertised. Maybe they fudged their braking action a bit? We will see.
Guest
Posts: n/a
From the video, did brakes and Spoilers have an effect?? Perhaps, but obviously not enough. Why pay attention to TR when it only acted for 9 seconds before the excursion?? It is guesswork, and two football fields through packed snow shows a good deal of energy left.
Join Date: Aug 2005
Location: fl
Posts: 2,525
Likes: 0
Received 0 Likes
on
0 Posts
As I stated earlier in another post I landed as a first flight into Reno and having an empty airplane didn't worry about runway length but after a snow storm being the first flight in with no braking action reports found the braking was nil and only reverse kept me from going off the end with a 737. We came slowly out of reverse at 80 knots and into idle at 60 knots. That is when with 3,000 feet left realized we could only stop with reverse thrust. We stopped fine but braking action reports should be available and accurate.
Join Date: Sep 2010
Location: Double Oak, Texas
Age: 71
Posts: 180
Likes: 0
Received 0 Likes
on
0 Posts
The south end of JAC is notoriously slippery at times during winter months. The passenger shot video out the left side of the AC never caught sight of a spoiler during the landing roll. On AA's RB211 engined fleet, if all systems are functioning as designed, the reverser sleeve will not translate aft in flight which would allow blocker doors to swivel into position to block fan air. Throttles must be at idle and separate levers mounted low on the front of the throttles must be grasped and raised by a pilot. The copilot was said by the NTSB to have been the PF. He would have been wrestling with the reverse levers. The captain would/should have a ready hand to deploy the ground spoilers if they not auto-deploy simultaneously with touchdown.
Join Date: Nov 1999
Posts: 2,312
Likes: 0
Received 0 Likes
on
0 Posts
During the time period when the air/ground parameter switched back to "air," the speed brake handle position momentarily moved toward the down position and then returned to the armed position where it stayed for the remainder of the recording.
From a performance standpoint, this is really where the problem lies. Reverse thrust is not normally a calculated factor in landing performance. Braking is of course, but without those spoiler panels up (automatically or manually) braking effectiveness is going to be significantly reduced.
If the above quoted preliminary finding, is correct or to be believed, then it will beg the question why the speedbrakes were not operated manually, when the lever didn't supposedly move to the up position on touchdown?
It is entirely possible, that there was a mechanical failure (alluded to here) that prevented such movement. It is possible that the movement of the lever between the down and armed position, and the sound of the drive motor may have provided some level of positive sensory re-inforcement if the crew were otherwise distracted.
All the information should be available to the investigators in this particular incident, so answers should be forthcoming in a reasonably short timescale.
Join Date: Dec 2001
Location: England
Posts: 1,389
Likes: 0
Received 0 Likes
on
0 Posts
A comment found elsewhere implies that speedbrakes are auto stowed if high thrust is applied on the ground. Sounds reasonable but...
If you have just landed and a reverser auto stow occurs.. does trying to apply full reverse thrust fool it into auto stowing the speed brakes as well?
If you have just landed and a reverser auto stow occurs.. does trying to apply full reverse thrust fool it into auto stowing the speed brakes as well?
Join Date: Nov 1999
Posts: 2,312
Likes: 0
Received 0 Likes
on
0 Posts
No it doesn't.
Application of reverse thrust should result in speedbrake deployment even if the speedbrake lever is down (not armed,) however cancelling reverse thrust will not cause the spoiler panels to retract or consequently the speedbrake lever to move.
According to the report given above, the speedbrake lever briefly moved from the armed to the down to the armed position, during the A/G transition phase at touchdown. It then apparantly remained in the armed position for the duration of the event.
In the ordinary course of events the speedbrakes should be deployed manually at touchdown if they do not deploy automatically. Failing that, they should deploy if and when the thrust reversers activate. However you would not rely on the latter feature to satisfy this requirement.
Application of reverse thrust should result in speedbrake deployment even if the speedbrake lever is down (not armed,) however cancelling reverse thrust will not cause the spoiler panels to retract or consequently the speedbrake lever to move.
According to the report given above, the speedbrake lever briefly moved from the armed to the down to the armed position, during the A/G transition phase at touchdown. It then apparantly remained in the armed position for the duration of the event.
In the ordinary course of events the speedbrakes should be deployed manually at touchdown if they do not deploy automatically. Failing that, they should deploy if and when the thrust reversers activate. However you would not rely on the latter feature to satisfy this requirement.
Join Date: Jan 2008
Location: farmm intersection, our ranch
Age: 57
Posts: 206
Likes: 0
Received 0 Likes
on
0 Posts
The lever will never move from armed to disarmed, or disarmed to armed on its own. They must be talking about the status of the auto speedbrake function, not the physical handle itself.
Join Date: Aug 2005
Location: fl
Posts: 2,525
Likes: 0
Received 0 Likes
on
0 Posts
The video is outside the spoiler panels so may or may not have been deployed. AA procedures is to manually deploy them if they didn't deploy. Also using reversers will deploy them if they are not armed. Braking is the question. Why couldn't they stop? Manual brakes should have worked fine. Auto brakes are not required to stop.
Join Date: Jun 2001
Location: Rockytop, Tennessee, USA
Posts: 5,898
Likes: 0
Received 1 Like
on
1 Post
During the time period when the air/ground parameter switched back to "air," the speed brake handle position momentarily moved toward the down position and then returned to the armed position where it stayed for the remainder of the recording.
The lever will never move from armed to disarmed, or disarmed to armed on its own. They must be talking about the status of the auto speedbrake function, not the physical handle itself.
The speedbrake lever has three labeled positions, Down, Armed and Up. When the lever is fully up on the quadrant, it is in the Down position. When it it fully down, it is in the Up postion. I wonder if the NTSB brief meant the handle briefly moved down to the Up position, then returned to Armed.
Kinda sounds like some of those possibly ersatz non-flying handling pilot procedures that were going around ops bulletin boards a few years ago.
If you lightly bounce on landing with a little extra power or gusty winds, sometimes the speedbrake lever will cycle as the tilt sensors load and unload before weight is fully on the wheels. Or, so I'm told...
Some carriers use manual speedbrakes (and throttles) for gusty landings, others do not. Looks like the speedbrake lever was indeed armed on this approach.
I have never seen a pilot deploy thrust reversers before touchdown. Has anybody else? They won't deploy in modern aircraft if you did so what difference does it make?
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 82
Posts: 1,454
Likes: 0
Received 0 Likes
on
0 Posts
bubbers44
I went to the effort of locating where the 757 outboard spoiler panels were supposed to be relative to the passenger video. A piece of the outboard spoiler should have been visible when the camera scanned aft. It is my opinion that the spoilers never deployed. Approximately 1 second before hitting the snow at the end, the camera angled back for an an instant and there was no spoiler visible then either.
The video is outside the spoiler panels so may or may not have been deployed.
Join Date: Aug 2005
Location: Europe
Posts: 97
Likes: 0
Received 0 Likes
on
0 Posts
T/R efficiency
Airbubba
What was the efficiency of "bucket" T/R compared to todays T/R?
Years ago those country boys at Piedmont had a homemade short field procedure on the 737-200 where they would pull the throttles to idle and pull back on the T/R levers in the flare. As soon as the gear touched down and the squat switches closed, the buckets would open without delay for a quick stop. Later when the 737-300's came along, the T/R levers were released by ten (or was it five?) feet radar altitude causing a spectacular fall from grace when the short field 'technique' was used.
Join Date: Jan 2006
Location: US
Posts: 2,205
Likes: 0
Received 0 Likes
on
0 Posts
tribo - someone might have the technical numbers but 'buckets' divert 100% of the air.
With fan engines only the fan(N1) airflow gets diverted. The core thrust is not part of the reverser thrust system.
Accelerating a fan(high bypass) engine in reverse actually increases the forward thrust from the core but it is offset by the increased stopping power of the fan(N1) thrust being diverted.
And different engines have different effectiveness. The PW engines on the 757 have better reverse thrust than the RR powered 757's.
With fan engines only the fan(N1) airflow gets diverted. The core thrust is not part of the reverser thrust system.
Accelerating a fan(high bypass) engine in reverse actually increases the forward thrust from the core but it is offset by the increased stopping power of the fan(N1) thrust being diverted.
And different engines have different effectiveness. The PW engines on the 757 have better reverse thrust than the RR powered 757's.
Join Date: Jan 2006
Location: US
Posts: 2,205
Likes: 0
Received 0 Likes
on
0 Posts
airbubba - "I wonder if the confusion is over nomenclature.
The speedbrake lever has three labeled positions, Down, Armed and Up. When the lever is fully up on the quadrant, it is in the Down position. When it it fully down, it is in the Up postion. I wonder if the NTSB brief meant the handle briefly moved down to the Up position, then returned to Armed."
-----------------------------------------------------------------------
Huh? Down is up, and up is down? 9,000+ hrs on the airplane and "up on the quadrant", along with your other explainations, confuses the heck out of me so I wonder how an ESL(english as a second language) person, or a non pilot, could understand your statements.
The handle fully forward is down(also 'stowed').
There's a slight detent that can be felt when the handle is first moved aft. That is the 'armed' detent and a light is activated that indicates the speedbrakes are 'armed'.
If the speedbrakes are 'armed' they should deploy with WOW(weight on wheels). Armed, or not armed, they should deploy when the thrust reversers are used.
Moving the handle aft(back/rearwards/deployed/out) deploys the speedbrakes in flight. With WOW it also deploys the inboard ground spoilers.
The autobrakes, if armed, should always work. If the braking action by the spoilers and reverse thrust is greater than the selected autobrake setting(1,2,3,4, max) the brakes don't engage until the total deacceleration rate is below the selected autobrake setting.
For example, thrust reverser and spoilers is about a deacceleration rate of just under 3. So if brakes 2 are selected the brakes won't be applied until thrust reverse effectiveness drops below '2' as the a/c slows.
If brakes 3 are selected the brakes are used slightly at high speed(w/thrust reverser and spoilers) and increase brake pressure as the a/c slows and thrust reverse effectivness decreases.
Brakes 4/MAX apply brakes harder throughout the landing.
From a pilot's perspective on a dry runway brakes 2 aren't felt until the thrust reversers are stowed. Brakes 3 are felt slightly during the landing roll. The application of brakes 4, or more, are obvious on a dry runway even when thrust reversers are being used.
Obviously runways less than dry have different reactions. The difference between what the pilots expect and what they actually experience is how 'reported braking action' reports are generated.
The speedbrake lever has three labeled positions, Down, Armed and Up. When the lever is fully up on the quadrant, it is in the Down position. When it it fully down, it is in the Up postion. I wonder if the NTSB brief meant the handle briefly moved down to the Up position, then returned to Armed."
-----------------------------------------------------------------------
Huh? Down is up, and up is down? 9,000+ hrs on the airplane and "up on the quadrant", along with your other explainations, confuses the heck out of me so I wonder how an ESL(english as a second language) person, or a non pilot, could understand your statements.
The handle fully forward is down(also 'stowed').
There's a slight detent that can be felt when the handle is first moved aft. That is the 'armed' detent and a light is activated that indicates the speedbrakes are 'armed'.
If the speedbrakes are 'armed' they should deploy with WOW(weight on wheels). Armed, or not armed, they should deploy when the thrust reversers are used.
Moving the handle aft(back/rearwards/deployed/out) deploys the speedbrakes in flight. With WOW it also deploys the inboard ground spoilers.
The autobrakes, if armed, should always work. If the braking action by the spoilers and reverse thrust is greater than the selected autobrake setting(1,2,3,4, max) the brakes don't engage until the total deacceleration rate is below the selected autobrake setting.
For example, thrust reverser and spoilers is about a deacceleration rate of just under 3. So if brakes 2 are selected the brakes won't be applied until thrust reverse effectiveness drops below '2' as the a/c slows.
If brakes 3 are selected the brakes are used slightly at high speed(w/thrust reverser and spoilers) and increase brake pressure as the a/c slows and thrust reverse effectivness decreases.
Brakes 4/MAX apply brakes harder throughout the landing.
From a pilot's perspective on a dry runway brakes 2 aren't felt until the thrust reversers are stowed. Brakes 3 are felt slightly during the landing roll. The application of brakes 4, or more, are obvious on a dry runway even when thrust reversers are being used.
Obviously runways less than dry have different reactions. The difference between what the pilots expect and what they actually experience is how 'reported braking action' reports are generated.
Last edited by misd-agin; 17th Jan 2011 at 14:48. Reason: added text
Join Date: Oct 2007
Location: fort sheridan, il
Posts: 1,656
Likes: 0
Received 0 Likes
on
0 Posts
we do need to use words properly. I prefer "Illuminate" to light up
I prefer deploy or extended
I prefer stowed or retracted
and abbreviations are surrounding us...TR? when I first learned TR it stood for transformer rectifier...and now everyone seems to say thrust reverser.
do you remember the old nursery rhyme: sticks and stones may break my bones but words will never harm me...unless I misunderstand and am flying a plane
I prefer deploy or extended
I prefer stowed or retracted
and abbreviations are surrounding us...TR? when I first learned TR it stood for transformer rectifier...and now everyone seems to say thrust reverser.
do you remember the old nursery rhyme: sticks and stones may break my bones but words will never harm me...unless I misunderstand and am flying a plane