AA A321 takes off after smashing ground sign

[1a sound asleep]

source

American Airlines A321-231 (N114NN) taxiing out at New York-JFK New York on flight #AA300 (https://www.facebook.com/hashtag/aa300?source=feed_text&epa=HASHTAG&__xts__%5B0%5D=68.ARBNzdFpnl_req-tWmKwY8aYQ9-mCcA0qTZP1sLPHBV9CJjKoy5zyZ45Qt4CI87Nw0H-EsRDGsTVmTP_Y42KR6X26cmZ8edfJrVsz9i02IW1OvyQ-92wUF1vIFkV8oJCopMDFX8aD6w4TURbaW19yN8AwPrvxiECQu3kvL_byNwHe hh3IZHi6BRoQr6LQskR9NDTryYivJ97EGamVkh-LQvCW-wD0lkiOpLsN4jHrVwEpDCfMagNEhOl30kjTPVSG8ZaFswRR09jn645qZBOk_ RH13TMPrkwqX3EW6Ok1xFByx29I8PazXGG8vLzmpfL74SFNM4ezNWh9kSsJZ dse63vOwQl&__tn__=%2ANK-R) to Los Angeles with 109 pax was damaged when its left outer wing struck a sign leaving a large dent on the wing.

Despite the damage, the flight took off.

The pilots then contacted the New York Center controller and stated their intentions to return to JFK Airport, citing they had a "strong roll to the left" on departure
https://www.facebook.com/AIRLINESECRETS/posts/2400655130207491

[DaveReidUK]

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/720x960/56585992_2400653246874346_2788057103707668480_n_9ebd3709fa56 d33b49ff63f121894bceb92012b0.jpg

https://www.facebook.com/hashtag/aa300?source=feed_text&epa=HASHTAG&__tn__=*NK-R

[jewitts]

US News reporting says passenger witnesses claim the plane went to a 90 degree angle on takeoff and hit a runway light. Doesn't sound right.

[RAC/OPS]

US News reporting says passenger witnesses claim the plane went to a 90 degree angle on takeoff and hit a runway light. Doesn't sound right.

sounds about right for a news report though!

[737 Driver]

Word is that at rotation, aircraft lurched left follow by left wing drop, and hit a runway remaining sign before liftoff.

Wake turbulence maybe?

[SteinarN]

sounds about right for a news report though!

Hahahaha :D

[chuks]

What sort of a sign would be installed on movement areas of an airport so high off the ground that a taxying aircraft could hit it with its outer wing? What is that, 15 or 20 feet up?

[DaveReidUK]

What sort of a sign would be installed on movement areas of an airport so high off the ground that a taxying aircraft could hit it with its outer wing? What is that, 15 or 20 feet up?

Other possible scenarios are available. :O

[Micky]

Other possible scenarios are available. :O

https://www.youtube.com/watch?v=d7sBJ7Qky8Y


Maybe there tried something like this

[BluSdUp]

Arch Du Liber!
This chap was brilliant , 62 enemy aircraft shot down in WW1
Barnstormer in the 20s and developed the Stuka in the 1930s together with Melitta Staufenberg.

[Sailvi767]

With 13L/31R closed until next Nov JFK tower is very reluctant to come off the 4/22 runways for landings regardless of crosswind. Don’t know the winds yesterday but there will be lots of crosswind training there this summer. If the go to 13/31 they are single runway ops which means massive delays.

[Airbubba]

AA300 reported 'we were banking an uncontrolled bank 45 degrees to the left' and 'an uncommanded roll to the left as we rotated' on takeoff to New York Center on 134.6 as they were leveling at FL200 and said they wanted to return to JFK. They said the aircraft was 'fine' but that they wanted to get it checked out.

[wiedehopf]

With 13L/31R closed until next Nov JFK tower is very reluctant to come off the 4/22 runways for landings regardless of crosswind. Don’t know the winds yesterday but there will be lots of crosswind training there this summer. If the go to 13/31 they are single runway ops which means massive delays.

Ironically they departed 31L from KE intersection with winds of 010 at 17 reported by tower prior to takeoff roll.

So 04L would have actually been less crosswind, but they were departing 04L and 31L KE dependingn on the first fix on the route.
(Flights with first fix RBV are in that scenario generally departed 31L KE)

[CurtainTwitcher]

LOL. Must be a near cousin of Lord Flasheart this guy.


"Captain Darling? Funny name for a guy isn't it? Last person I called darling was pregant twenty seconds later"Blackadder: Always treat your kite like you treat your woman - Lord Flashearthttps://youtu.be/3noZ3v9kEyM

[Auxtank]

The R & N thread is becoming the domicile of non-pilots and jokers with little emphasis paid/ professional input applied, to the story being told who think Blackadder was funny. It was in parts, like the curate's egg.

But really, this thread should be a serious discussion (does anyone remember how to do that?) on current affairs and industry news, rumours, happenings, reported mishaps and upsets and accidents.

Save the other stuff for Jet Blast.

[WingNut60]

...........

Save the other stuff for Jet Blast.

Some funny things happening with PPRune site at the moment; thread jumps, lost posts, etc.
The Blackadder post seems right out of context (to me).

Maybe just a victim of the thread jumping.

[FlightlessParrot]

Arch Du Liber!


Which, being interpreted (and de-autocorrected to Ach! Du Liebe) meaneth: F'ing Hell!

[Jet Jockey A4]

So...

The aircraft struck something on the ground while taxiing and no one onboard noticed anything before the takeoff?

The pilots did not feel a thump?

The flight attendants did not feel, hear or even see anything?

The passengers on the left side of the aircraft with window seats did not see anything?

The pilots reported problems with the handling of the aircraft at takeoff but yet climbed to FL200?

What's going on here?

[Loose rivets]

Is it conceivable a part of the sign remained hooked on the wing for a few seconds?

[737 Driver]

So...

The aircraft struck something on the ground while taxiing and no one onboard noticed anything before the takeoff?

The pilots did not feel a thump?

The flight attendants did not feel, hear or even see anything?

The passengers on the left side of the aircraft with window seats did not see anything?

The pilots reported problems with the handling of the aircraft at takeoff but yet climbed to FL200?

What's going on here?

What appears to have happened is that for yet undetermined reasons, right at rotation the aircraft lurched to the left with a significant wing drop. During the ensuing excursion, the left wingtip struck the 5000' remaining marker before becoming airborne. Passengers and flight attendants did report the damage to the flight deck, and the aircraft returned to JFK.

That is about all we know right now. Let the investigators investigate.

[oliver2002]

Avherald has indicated where the sign is located on the map:
https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/750x469/american_a321_n114nn_new_york_190410_map_0880c5a5fce5402a520 b0959ba1779e43f02ea5f.jpg

The signs there are what 4-6ft tall?? How much did this aircraft bank? With wind right on the nose?? Are they not allowing for sufficient spacing during single rwy ops?

[The Ancient Geek]

This should never happen.
All ground furniture adjacent to a runway or taxiway MUST be frangible. If an airport fails to comply with regulations someone is due for a severe talking to.

[DaveReidUK]

This should never happen.
All ground furniture adjacent to a runway or taxiway MUST be frangible. If an airport fails to comply with regulations someone is due for a severe talking to.

Just because something is frangible (i.e. will break or yield on impact), doesn't mean you can hit it without sustaining any damage.

[skadi]

So...

The aircraft struck something on the ground while taxiing....

Not during taxiing, it happend short after takeoff.

skadi

[DaveReidUK]

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/957x485/jfk_runway_marker_a97be9e8176eb168896d8a44d3ce7ba07006563a.j pg

[maggot]

What's the width of that strip? CL!

[Doors to Automatic]

The width of the strip if it is standard (which I think it is) is 150ft plus (looks like) 60ft shoulder either side. What position the aircraft must have been in to hit that sign on rotation I can only imagine. All I can say is I am glad I wasn't a passenger on that flight!

[fdr]

yikes.

the damage is the outcome of a weirdness not the cause. QAR/DFDR/CVR will be interesting.

[Wake Turbulence]

Per the Port Authority website:
Runway 13R-31L is 14,511 feet long by 200 feet wide and is one of the longest commercial runways in North America.

https://www.panynj.gov/air-cargo/jfk-runways.html

[b1lanc]

Citing AVH,
"According to information The Aviation Herald received on Apr 12th 2019 ground tracks reveal the aircraft was dragging its left wing tip for quite some distance on the ground, the ground tracks even suggest the aircraft came close to ground loop.:eek:

The aircraft and left wing tip became airborne just ahead of the runway sign, the left wing tip impacted the sign, parts of which became embedded in the left wing tip. The wing also sustained according damage to its underside near the wingtip."

[chuks]

An A321 has a wingspan of 35.8 m, according to Wikipedia.

Assume it's on the centerline of a 61-meter (200-foot) wide runway.

30.5 m, runway centerline to edge - 17.9, half the wingspan of an A321 = 12.6 m (41 feet), distance from wingtip to runway edge.

An A321 should have a clearance of 12.6 m, or 41 feet, from each wingtip to each edge of the runway.

From the runway edge to the sign that was struck looks like another 75 feet or so, just guessing from the image shown. Let's call it about 22 m.

12.6 m wingtip to runway edge + 22 m runway edge to sign = 34.6 m wingtip to sign.

That would place the sign about 35 m (115 feet) from the wingtip when the aircraft is on centerline.

If all this stuff is correct then that machine must have been quite far off the runway when it hit that sign, about 120 feet laterally displaced on a runway that is 100 feet wide from centerline to edge. Wow!

[Fergus Kavanagh]

..... when he rolled LEFT on rotation he might just have moved LEFT as a result, and collected the sign on the LEFT side of the runway, his LEFT wing being low enough to clip it.?

Do the newsrags deliberately mis-state the facts to allow them to spice up the headlines.? I think they do. Including the almighty Beeb.

[wiedehopf]

The signs there are what 4-6ft tall?? How much did this aircraft bank? With wind right on the nose?? Are they not allowing for sufficient spacing during single rwy ops?
They were not running single runway ops. Arriving 4R and 4L, departing 4L and 31L intersection KE.

The wind given by tower prior to takeoff was 010 at 17.
Where do people get wind straight down the nose?

[hawk76]

04/158 (a3244/19) - rwy 31l 5000ft dist remaining sign missing. 11 apr 05:13 2019 until 25 may 02:00
2019. Created: 11 apr 05:13 2019

[Meester proach]

You can guarantee your margins will always be reduced by JFK. Pick the most into wind runway then pick another, an obsession with that Canarsie, and VOR approaches ....it’s like stepping back to 1975

[Jet Jockey A4]

What appears to have happened is that for yet undetermined reasons, right at rotation the aircraft lurched to the left with a significant wing drop. During the ensuing excursion, the left wingtip struck the 5000' remaining marker before becoming airborne. Passengers and flight attendants did report the damage to the flight deck, and the aircraft returned to JFK.

That is about all we know right now. Let the investigators investigate.

Thank you.

[bill fly]

Looks like someone needs to brush up on his crosswind take-offs.
So far nobody mentioned skills. Oh perhaps the pilots were not “foreign” enough...

[JW411]

Meester proach: "It's like stepping back to 1975".

What was wrong with 1975? I thought it was pretty good.

[737 Driver]

Looks like someone needs to brush up on his crosswind take-offs.
So far nobody mentioned skills. Oh perhaps the pilots were not “foreign” enough... If it turn out that crew skill was a contributing factor, then that will be fair game for comment. However, there are other possible causes. In fact, it is entirely possible that crew skill kept this incident from becoming a hull loss. Why don't we hold judgement until there is at least a preliminary report?

[SamYeager]

If it turn out that crew skill was a contributing factor, then that will be fair game for comment.
Looking forward to this quote appearing on all discussions of non US airline incidents. /s

[nike]

Seen it plenty of times where the downwind wing in a swept wing jet is allowed to drop at rotation due to the PF being slow or not anticipating.

But this sounds like such a large lateral movement to end up that far off the centerline in a narrow body that you naturally feel there is more to the story than poor rotation technique.

[delarue]

LOL. Must be a near cousin of Lord Flasheart this guy.
https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/983x509/lord_flashheart_a95a40e8e4f5f4d4bbba0f1b4627a599cfdac94e.jpg

"Captain Darling? Funny name for a guy isn't it? Last person I called darling was pregant twenty seconds later"

Hehe! I was watching that episode just a couple of days ago. Now let's go inside and talk about me.

[USN O6]

If it turn out that crew skill was a contributing factor, then that will be fair game for comment. However, there are other possible causes. In fact, it is entirely possible that crew skill kept this incident from becoming a hull loss. Why don't we hold judgement until there is at least a preliminary report?

One of the best posts I've seen in these forums!

[Longtimer]

American A321 suffers un-commanded roll during takeoff incident

17 April, 2019
SOURCE: Flight Dashboard
BY: Jon Hemmerdinger
Boston
An American Airlines Airbus A321 experienced what a pilot called an “un-commanded” roll and struck runway equipment during takeoff on 10 April from New York John F Kennedy.

The aircraft took off from the airport at about 20:40 local time, bound for Los Angeles as American flight 300.

“When we departed… strong roll to the left… as we climbed out,” the pilot told air traffic controllers shortly after takeoff, according to an audio recording from LiveATC.net.
“We were banking… Uncontrolled bank 45° to the left.”
“Turbulence from another aircraft?” the pilot adds.
“I don’t think so. There’s a good crosswind, but we had an un-commanded roll to the left as we rotated.”

The pilot also tells controllers that the aircraft was at that point “flying great”, and he requests clearance to return to JFK, where the A321 landed without incident at 21:09.

The US Federal Aviation Administration is investigating, it says.

“The pilot reported that the Airbus A321 may have collided with an object during departure earlier in the evening,” the FAA tells FlightGlobal. “After the aircraft landed, workers discovered damage to the left wing, possibly caused by striking a runway sign and airport light.”

American confirms in a statement to FlightGlobal that the aircraft “struck an object upon departure”, adding it is investigating the incident in

[Airbubba]

The NTSB is going to take a look:

NTSB is investigating the April 10, 2019, accident at JFK International Airport, New York, involving an American Airlines A321, operating as American Airlines flight 300, which experienced a roll during takeoff and hit a runway distance marker with the left wingtip.10:36 AM - 17 Apr 2019

https://twitter.com/NTSB_Newsroom/status/1118568832875024394

[bill fly]

One of the best posts I've seen in these forums!

Why, because you are not foreign? Take a look at a couple of other threads around here, to see how it usually goes down...

[b1lanc]

The NTSB is going to take a look:



https://twitter.com/NTSB_Newsroom/status/1118568832875024394

This from AVH - passenger allegedly on board the flight:

" I was aboard this aircraft. The take off was fast, rather quick and felt short. Then we pitched down and banked right (left wing up) and then left (right wing up) and the back felt to skid out sideways, I was in the window seat just behind the left wing. Then it felt like the pilot pulled the aircraft up manually. He continued to make very strong left and right banks while in the air before we circled back to JFK. He made an announcement that we had a major computer failure, but that he had control of the airplane and that we'll be making an emergency landing. I watched the metal flap above the wind the whole 43 mins we were in the air. The flight attendants went to the exit rows and said "this is not a drill" can you open the emergency doors to the passengers. I want to hear the audio and see the faa report. If anyone knows how long or where to look for this information that would be greatly appreciated. Thank you "

[Chu Chu]

The passenger's description sounds a lot like the recent BA incident at Gibraltar.

[737 Driver]

https://www.cbsnews.com/news/american-airlines-flight-300-jfk-close-call-appears-worse-than-first-reported/

​​​​​​ (https://www.cbsnews.com/news/american-airlines-flight-300-jfk-close-call-appears-worse-than-first-reported/)A close call for American Airlines Flight 300 (https://streamable.com/v7ur3) at New York's John F. Kennedy International Airport now appears far worse than first reported. Sources tell CBS News the Airbus with 102 passengers and eight crew on board "nearly crashed" last week when the wing scraped the ground and hit a sign and light pole during takeoff.

"We were banking, uncontrolled bank 45 degrees to the left," a pilot could be heard saying on the air traffic control audio of the incident.

"Turbulence from another aircraft?"

"I don't think so. There's a good cross wind but we had an uncommanded roll to the left as we rotated," he responded.

One source briefed on the incident told CBS News: "That was as close as anybody would ever want to come to crashing." According to people familiar with the ongoing investigation, preliminary indicators are that there was a "loss of control" on takeoff, reports CBS News correspondent Kris Van Cleave.

The Airbus A321 took off around 8:40 p.m. on April 10, bound for Los Angeles. But just as the plane was beginning to lift off, it rolled to the left, causing the wing tip to scrape the ground. The wing then hit a runway sign and a light pole before pilots managed to regain control and continued the takeoff. The force of the impact bent the wing.

The flight returned to JFK 28 minutes later with no injuries reported. American Airlines tells CBS News, the airline "is investigating this incident in coordination with federal authorities."

The FAA is investigating and have not determined why the plane banked sharply at a critical moment of takeoff. The NTSB has requested data from the incident. After this report, the NTSB also announced a formal investigation, saying in the statement: "The FAA, American Airlines, and the Allied Pilots Association will be parties to the NTSB's investigation, and the BEA of France has designated an Accredited Representative as the state of design and manufacture of the airplane with Airbus as their technical advisor."

[Airbubba]

Some pictures from social media:


https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/900x1200/d4yusnexkaadnxn_e8b1a1a358d58f2e7da31eb54679b43485dadaa0.jpg
https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/768x1024/d4yusniw0aibw3z_a51d495935d363fd6bf619acf01e16d7198209ff.jpg
https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/900x1200/d4yusnjx4aedvrd_b21fa7be9d7ac387ebe5d8e87d4d25e2ef8fd842.jpg
https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/900x1200/d4yusnfx4ai1kkj_811d018090c33e0cf1250f21377ab9675faea5a0.jpg

[Pilot DAR]

It can be seen that not only the wingtip dragged the ground, but even the aileron shows abrasion from being deflected to lift the wing. The absence of any earth around the abrasion spot suggests to me that it dragged pavement or concrete only. And the wing hit several things, not just one....

[Airbubba]

More from the NTSB:

AA Flight 300: Team of 6, consisting of an investigator in charge & technical subject matter experts in vehicle recorders, flight ops, aircraft systems & performance assigned to investigation. NTSB not planning to send investigators to the scene, but will if/when needed.

https://twitter.com/NTSB_Newsroom/status/1118601691086016512

[flysmiless]

According to an audio recording form liveatc "we were banking... unconrolled bank 45° to the left."

this is so pathetic..

[Banana Joe]

What's more pathetic are some Americans pilots in various sites and FB group blaming the aircraft. It's either the foreign aircraft or foreign pilots' fault.

Let them believe they're God's gift to aviation...

[PerPurumTonantes]

Good demonstration of wing strength - hit a sign at ~150mph, with the thinnest part of the wing, only got a couple of dents and was still flyable.

[Sailvi767]

What's more pathetic are some Americans pilots in various sites and FB group blaming the aircraft. It's either the foreign aircraft or foreign pilots' fault.

Let them believe they're God's gift to aviation...

It appears it was in fact a aircraft malfunction. More will come out in the next few days.

[DaveReidUK]

And the wing hit several things, not just one....

You don't think the two impact points are just from the two uprights that support the "distance remaining" sign (one of which still appears to be embedded in the L/E) ?

Using the wing chord as a reference, they appear to be around 4 feet apart, which sounds about right.

Hitting two separate items of airfield furniture would be particularly unfortunate, and it's not immediately obvious what a second one could have been.

[Jet Jockey A4]

It appears it was in fact a aircraft malfunction. More will come out in the next few days.

Agreed... Can we just wait to see some actual facts before pointing the finger at anyone or anything!

[737 Driver]

What's more pathetic are some Americans pilots in various sites and FB group blaming the aircraft. It's either the foreign aircraft or foreign pilots' fault.

Let them believe they're God's gift to aviation...

Take a stroll over to the Atlas Air 767 thread and see if you still believe this to be the case.

[Jet Jockey A4]

Take a stroll over to the Atlas Air 767 thread and see if you still believe this to be the case.

Can't believe how long it is taking to get some real facts from either the FAA or NTSB on that accident.

[SeenItAll]

What's more pathetic are some Americans pilots in various sites and FB group blaming the aircraft. It's either the foreign aircraft or foreign pilots' fault.

Let them believe they're God's gift to aviation...

Banana: Just to note, "aircraft malfunction" can be due to some design fault, some structural or software failure, or perhaps shoddy maintenance. Calling the problem that is not tantamount to blaming Airbus. Indeed, the famous AA DC-10 crash out of ORD was not really due to any McDonnell Douglas fault, but improper technique used by AA engineers to replace the port engine. So cool your presumptive jets and wait for the investigation.

[ImbracableCrunk]

Wow. You can actually see the distance remaining marker wrapped around the wing.

[dogsridewith]

USA am TV news says wing tip scraped ground and a runway light is imbedded in the wing.

[fox niner]

Why are those distance remaining signs there in the first place? Certainly not because of an ICAO directive.

[DaveReidUK]

Why are those distance remaining signs there in the first place? Certainly not because of an ICAO directive.

FAA Standards for Airport Sign Systems (https://www.faa.gov/documentlibrary/media/advisory_circular/150_5340_18f.pdf)

Chapter 2.

[DaveReidUK]

USA am TV news says wing tip scraped ground and a runway light is imbedded in the wing.

Might be better to believe what JFK and the NTSB say.

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/790x158/jfk_notam_3303e2cbd9195a7ae1b8f5123ff5cd3337932aca.jpg

[Banana Joe]

Banana: Just to note, "aircraft malfunction" can be due to some design fault, some structural or software failure, or perhaps shoddy maintenance. Calling the problem that is not tantamount to blaming Airbus. Indeed, the famous AA DC-10 crash out of ORD was not really due to any McDonnell Douglas fault, but improper technique used by AA engineers to replace the port engine. So cool your presumptive jets and wait for the investigation.
Might as well be. As far as I know Airbus had to change put in place some changes more than once after some events. Like the LH overran in Warsaw and the LH wing strike in Hamburg.

My point was that also with the Atlas Air there have been assumptions about the FO's ability without waiting for the preliminary report, because allegedly he was pushed by the HR dept thanks to his race. Many said he was also fired by TWA in the 90's. I call that, with all due respect, BS.

[Airbubba]

Many said he was also fired by TWA in the 90's. I call that, with all due respect, BS.

Who are these 'many'? Can you provide a reference?

aterpster had the Atlas FO confused with the captain in the UPS 1354 crash and subsequently posted a correction:

The F/O previously worked for TWA. As I understand it he left there in 1990.

Then, I must have been given bad information. Do you know his age on the date of the accident?

EDIT: The person who had been let go by TWA was the captain of UPS 1354. Sorry for the confusion.

[Banana Joe]

On US centric forums.

[Reluctant Bus Driver]

What was the cause of the BA Airbus out of Gibraltar doing the " wing walk"?
Some months ago I was landing a 319 and it started doing that over the numbers. Wind was not a factor and I'm pretty sure I didn't start it. Almost went around before it settled down. Wondering if experienced Airbus pilots can chime in if they have had similar experiences. Kinda hard for me to believe, not knowing all the facts, that the JFK incident could have been pilot induced.

[AKAAB]

From 19 years of personal experience as a captain on the A320, I can confidently state that 90%+ of the pilots I fly with don't put any crosswind correction in for the takeoff roll. On rotation with a strong crosswind, there is usually a rudder wag and quick correction as the nose comes up and the plane tries to simultaneoulsy roll away from the wind and weathervane into the wind. This fits what we know so far.

My inital instructor at Airbus told us to not use crosswind aileron inputs because the computers would take care of it and you didn't want to get spoiler extension. This was proved patently incorrect and it's now clearly spelled out in the FCOM. I had a new FO right out of IOE that could not land the plane. Upon discussing his difficulties, he said he was taught (at Airbus Miami) to never use cross-controls for landing. With some new knowlege and coaching, he was easily able to handle crosswinds. Again, I suspect there is some old, bad tribal knowledge still out there.

I'd place a bet on this being a factor.

[aterpster]

NTSB has classified this as an accident. I understand they dispatched a Go Team of 6 to JFK.

We'll find out a lot in due course.

https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/789x1149/aal_jfk_6fe38c2d408e3a68b57236ac5695e17173f6e824.jpg

[Smythe]

Looking at quite a few of the recent events where aircraft are banking hard on DEP, I believe we are seeing the effects of reduced spacing on DEP, especially with similar aircraft. Spacing is far too close between similar variants.

I recently experienced a severe event, in an A321 behind an A320. About 60 seconds behind the A320, we had just rotated, when a hard right, followed by a hard left bank at about 300 feet. Felt like a vertical roller coaster as well.

There have been several very similar events recently in the aviation news, with uncommanded bank at low altitudes, and I am just wondering if this reduced spacing is an issue.

[AKAAB]

Looking at quite a few of the recent events where aircraft are banking hard on DEP, I believe we are seeing the effects of reduced spacing on DEP, especially with similar aircraft. Spacing is far too close between similar variants.

I recently experienced a severe event, in an A321 behind an A320. About 60 seconds behind the A320, we had just rotated, when a hard right, followed by a hard left bank at about 300 feet. Felt like a vertical roller coaster as well.

There have been several very similar events recently in the aviation news, with uncommanded bank at low altitudes, and I am just wondering if this reduced spacing is an issue.

JFK typically uses distance instead of time for determining the departure spacing. They get annoyed when someone gets cleared into position and they respond they need the full two minutes for wake turbulence.

[threemiles]

The take off was fast, rather quick and felt short. Then we pitched down and banked right (left wing up) and then left (right wing up) and the back felt to skid out sideways
I would look at takeoff data in the FMS. Emirates, Melbourne, I guess was the one.

[Smythe]

My inital instructor at Airbus told us to not use crosswind aileron inputs because the computers would take care of it and you didn't want to get spoiler extension. This was proved patently incorrect and it's now clearly spelled out in the FCOM.

I think most are concerned about tailstrike..

[pattern_is_full]

What was the cause of the BA Airbus out of Gibraltar doing the " wing walk"?
Some months ago I was landing a 319 and it started doing that over the numbers. Wind was not a factor and I'm pretty sure I didn't start it. Almost went around before it settled down. Wondering if experienced Airbus pilots can chime in if they have had similar experiences. Kinda hard for me to believe, not knowing all the facts, that the JFK incident could have been pilot induced.

Aviation Herald reports this from a passenger - whom they contacted and received documentation from that she was aboard.

"I was aboard this aircraft. The take off was fast, rather quick and felt short. Then we pitched down and banked right (left wing up) and then left (right wing up) and the back felt to skid out sideways, I was in the window seat just behind the left wing. Then it felt like the pilot pulled the aircraft up manually. He continued to make very strong left and right banks while in the air before we circled back to JFK. He made an announcement that we had a major computer failure, but that he had control of the airplane and that we'll be making an emergency landing. I watched the metal flap (runway sign) above the windg the whole 43 mins we were in the air.

Accident: American A321 at New York on Apr 10th 2019, wingtip strike and collision with runway sign during departure (http://avherald.com/h?article=4c68c5a8&opt=0)

I'm agnostic as to 1) crosswind or 2) Airbus software glitch, combined perhaps with PIO in response or 3) wake turbulence or 4) something else. They have all occurred at one time or another, and it won't astound me if any particular one is identifed as the cause or a factor, eventually.

[dogsridewith]

USA am TV news says wing tip scraped ground and a runway light is imbedded in the wing.
Might be better to believe what JFK and the NTSB say.

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/790x158/jfk_notam_3303e2cbd9195a7ae1b8f5123ff5cd3337932aca.jpg

From AV Herald article that was updated today:
"According to information The Aviation Herald received on Apr 12th 2019 ground tracks reveal the aircraft was dragging its left wing tip for quite some distance on the ground, the ground tracks even suggest the aircraft came close to ground loop. The aircraft and left wing tip became airborne just ahead of the runway sign, the left wing tip impacted the sign, parts of which became embedded in the left wing tip. The wing also sustained according damage to its underside near the wingtip.

In the afternoon the FAA reported: "AMERICAN AIRLINES FLIGHT 300 AIRBUS 321 STRUCK RUNWAY SIGN AND AIRPORT LIGHT". The FAA reported no injuries and unknown damage to the aircraft."

(So TV reported wrong component of airport stuck in the wing.)

[DaveReidUK]

From AV Herald article that was updated today:
"According to information The Aviation Herald received on Apr 12th 2019 ground tracks reveal the aircraft was dragging its left wing tip for quite some distance on the ground, the ground tracks even suggest the aircraft came close to ground loop. The aircraft and left wing tip became airborne just ahead of the runway sign, the left wing tip impacted the sign, parts of which became embedded in the left wing tip. The wing also sustained according damage to its underside near the wingtip.

It will be interesting to see if the NTSB agrees with Avherald's (unattributed) report that "the ground tracks even suggest the aircraft came close to ground loop".

[hans brinker]

From 19 years of personal experience as a captain on the A320, I can confidently state that 90%+ of the pilots I fly with don't put any crosswind correction in for the takeoff roll. On rotation with a strong crosswind, there is usually a rudder wag and quick correction as the nose comes up and the plane tries to simultaneoulsy roll away from the wind and weathervane into the wind. This fits what we know so far.

My inital instructor at Airbus told us to not use crosswind aileron inputs because the computers would take care of it and you didn't want to get spoiler extension. This was proved patently incorrect and it's now clearly spelled out in the FCOM. I had a new FO right out of IOE that could not land the plane. Upon discussing his difficulties, he said he was taught (at Airbus Miami) to never use cross-controls for landing. With some new knowlege and coaching, he was easily able to handle crosswinds. Again, I suspect there is some old, bad tribal knowledge still out there.

I'd place a bet on this being a factor.

my current manual:
Pilot Flying | Takeoff Expanded (continued)
At VR:
• ROTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15° THEN SRS
- At VR, initiate the rotation to achieve a continuous rotation with a
rate of about 3° per second, towards a pitch attitude of 15° (12.5° if
one engine is failed).
- Minimize the lateral inputs on the ground and during the rotation to
avoid spoiler extension.
- In strong crosswind conditions, small lateral stick inputs may be
used, if necessary, to aim at maintaining wings level.

[Smythe]

"I was aboard this aircraft. The take off was fast, rather quick and felt short. Then we pitched down and banked right (left wing up) and then left (right wing up) and the back felt to skid out sideways, I was in the window seat just behind the left wing. Then it felt like the pilot pulled the aircraft up manually. He continued to make very strong left and right banks while in the air before we circled back to JFK.

Sounds like a wake encounter.

[booze]

Sounds like a wake encounter.
Wake encounter in such crosswind?! Sounds like pisspoor piloting skills to me.

[b1lanc]

It will be interesting to see if the NTSB agrees with Avherald's (unattributed) report that "the ground tracks even suggest the aircraft came close to ground loop".

I would think that some marks would exist if true and haven't seen anything 'leaked' yet. Pics of wing damage are available.

[thundersnow9]

Wake encounter in such crosswind?! Sounds like pisspoor piloting skills to me.

SLF here. Just wondering if perhaps a wake from an aircraft departing 31R could have propagated downwind to 31L given the breeze. I've hit by more than a few wakes while sailing close to the runways in BOS, they do seem to sink fairly efficiently.

[A321drvr]

SLF here. Just wondering if perhaps a wake from an aircraft departing 31R could have propagated downwind to 31L given the breeze. I've hit by more than a few wakes while sailing close to the runways in BOS, they do seem to sink fairly efficiently.
​​​The two parallel runways mentioned are just too far from eachother with lots of obstacles, like terminal buildings, etc. in between.

[SquintyMagoo]

I hope AA isn't again training in aggressive use of rudder pedals in turbulence as before the AA 587 crash.

[Smythe]

Wake encounter in such crosswind?! Sounds like pisspoor piloting skills to me.
Sorry, I dont see the crosswind details anywhere.

Would also have to see where at this airport the crosswinds are measured.

[Loose rivets]

The problem seems to be establishing just what the manufacturer stipulates, and how strictly that's interpreted as SOP.

A pal of mine had a friendly chat with a boss about holding the side-stick back slightly during the deceleration run. Such a small issue; a hangover from the old days. So what of crossing the controls on take off? If allowed at all, I'm sure it wouldn't be great handfuls of stick and rudder like the DC3 days.

There was a discussion a year or so back about crossing up upon landing. I was pleasantly surprised at a few more experienced posters being very for this technique. This was after a near wing-tip scraping landing with a major thump when the starboard wheels came down.

[tdracer]

Wake encounters are pretty obvious and distinctive on a DFDR review.
Not suggesting it was (or wasn't) a wake encounter, but they should readily be able to tell fairly quickly.

[FIRESYSOK]

Handling skills are now tertiary to what managers are looking for in a newly-hired pilot. There is a presumption - by HR types - that pilots should first be customer service agents, then pilots. Flying can be trained after the fact. That’s their opinion. Anything goes to be the most PC company now.

[booze]

Sorry, I dont see the crosswind details anywhere.

Would also have to see where at this airport the crosswinds are measured.
KJFK 110051Z 36017KT 10SM SCT250 10/M03 A2998 RMK AO2 SLP153 T01001028=
KJFK 102351Z 33015KT 10SM FEW070 FEW250 11/M03 A2996 RMK AO2 PK WND 34026/2257 SLP145 T01111028 10161 20111 53034=
TWR wind was 010/17 prior takeoff roll.
Anemometers are placed along all RWYs, although I'm not sure about their spacing or number.

[Longtimer]

Just imagine the comments if this had happened to a 3rd world carrier..... Just Saying!

[hans brinker]

Just imagine the comments if this had happened to a 3rd world carrier..... Just Saying!

https://aviation-safety.net/airlinesafety/industry/reports/IATA-safety-report-2017.pdf

pg 47:
Regional Accident Rate (2013-2017) Accidents per Million Sectors
North America, north Asia, and EU around 1.
Asia/pacific, Latin america, Middle east 2-3
Africa/Russia 4-6
Just Saying!

[Smythe]

33015KT
Wind direction 330 at 15 kts, peak 23, runway direction 313.9...

crosswind? 5kts?

[Airbubba]

SLF here. Just wondering if perhaps a wake from an aircraft departing 31R could have propagated downwind to 31L given the breeze. I've hit by more than a few wakes while sailing close to the runways in BOS, they do seem to sink fairly efficiently.

Not a player in this case:

JFK 03/759 JFK RWY 13L/31R CLSD 1904010300-1911162200

This NOTAM in secret coded format says that runway 31R was closed when the mishap occurred.

The aircraft taking off on 31L prior to American 300 was Envoy 4077, an EMB-135, about two minutes earlier. Just before AA300 started to roll (in more than one sense) Avianca 244 was landing on 4R and Delta 408 was taking off on 4L, both A330-200's:


https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/1580x813/aal300_cee86791d5ae0a7ed1a0808063dfa8ebf1190d52.jpg

[Smythe]

Well, I dont think an ERJ caused a wake...nor a mild crosswind...
dragging a wing for a bit and taking out a sign....damn.

!JFK 03/760 JFK RWY 13L/31R WIP CONST LGTD AND BARRICADED 1904010300-1911162200
CREATED: 29 Mar 2019 21:44:00
SOURCE: JFK

!JFK 03/759 JFK RWY 13L/31R CLSD 1904010300-1911162200
CREATED: 29 Mar 2019 21:43:00
SOURCE: JFK

Finished work early? NOTAMS for closure, not for open!
So many crane obstruction NOTAMS hanging out there...

https://pilotweb.nas.faa.gov/PilotWeb/notamRetrievalByICAOAction.do?method=displayByICAOs&reportType=RAW&formatType=ICAO&retrieveLocId=KJFK&actionType=notamRetrievalByICAOs (https://pilotweb.nas.faa.gov/PilotWeb/notamRetrievalByICAOAction.do?method=displayByICAOs&reportTy pe=RAW&formatType=ICAO&retrieveLocId=KJFK&actionType=notamRe trievalByICAOs)

[FrequentSLF]

Wingtip Scuffed In Takeoff Mishap - AVweb flash Article (http://flash.avweb.com/avwebflash/news/Wingtip-Scuffed-In-Takeoff-Mishap-232674-1.html)

Another...

[booze]

33015KT
Wind direction 330 at 15 kts, peak 23, runway direction 313.9...

crosswind? 5kts?
Reported TWR wind was 010/17. Anyhow even 5 kts of crosswind is enough to highly reduce the effect of wake caused by the preceding aircraft, if any.

[737 Driver]

Reported TWR wind was 010/17. Anyhow even 5 kts of crosswind is enough to highly reduce the effect of wake caused by the preceding aircraft, if any.

Actually, a light crosswind can actually make it worse. Wingtip vortices move slowly outward away from the departure runway. A light crosswind can effectively hold the upwind vortex on the runway. Not saying that's the case here, but it's something to consider when judging your separation needs.

[booze]

Actually, a light crosswind can actually make it worse. Wingtip vortices move slowly outward away from the departure runway. A light crosswind can effectively hold the upwind vortex on the runway. Not saying that's the case here, but it's something to consider when judging your separation needs.

https://www.faa.gov/training_testing/training/media/wake/04SEC2.PDF


https://cimg7.ibsrv.net/gimg/pprune.org-vbulletin/766x697/me01x_1a4c6c2c9cbcf61363ea81db5876705e9cc66ea2.png

[Smythe]

Actually, a light crosswind can actually make it worse. Wingtip vortices move slowly outward away from the departure runway. A light crosswind can effectively hold the upwind vortex on the runway. Not saying that's the case here, but it's something to consider when judging your separation needs.

Dont get me wrong, it does seem like a wake encounter... (eye witness says it banked right first, then left) but it was only an ERJ 135, while the ERJ likely rotated much earlier on the rwy that the A321, it was 2 minutes prior. The wake could have settled just at the ground level, and the 321 got it, but ....
the A321 had problems right at rotation. ground tracks reveal the aircraft was dragging its left wing tip for quite some distance on the ground, the ground tracks even suggest the aircraft came close to ground loop.

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1200x675/1812p_pe_wake1_16x9_eed6253f0a9b81e48ffa7b24b398f8544358e582 .jpg

[b1lanc]

Citing AVH,
"According to information The Aviation Herald received on Apr 12th 2019 ground tracks reveal the aircraft was dragging its left wing tip for quite some distance on the ground, the ground tracks even suggest the aircraft came close to ground loop.


I have yet to see any other source confirm this.

[Smythe]

True, but a pretty good sanding down of the wingtip...definite contact

[Dani]

It appears it was in fact a aircraft malfunction.

Be it what it was... - I'm less concerned about the actual happening than by the handling therafter: Why on earth would you continue your flight to FL 200 and only then realize you have to return? Would they have continued to LAX if they wouldn't have a roll problem?
There might be legitimate reasons why you get a wing touching the surface, but thereafter you do never continue the flight. Period.
This is what frightens me about this AA crew. Haven't they checked their wings after the rotation? Have they thought about keeping the slats out with structural damage?!

[Airbubba]

Here are the edited ATC comms from VASAviation (looks like the wrong tail number in the video):

https://youtu.be/Ca-0Bi2lZhg

The AA300 crew seems to minimize the seriousness of the situation and says they don't need any assistance on the ground. They apparently didn't declare an emergency.

[aterpster]

Rumor has it they took off with full aileron trim. Stay tuned.

[Jet Jockey A4]

Rumor has it they took off with full aileron trim. Stay tuned.


No out of range for takeoff trim warning on the Airbus?

[rowdyyates]

Love it !!!

[tubby linton]

Rumor has it they took off with full aileron trim. Stay tuned.
Interesting as the Airbus doesn’t have one

[West Coast]

Be it what it was... - I'm less concerned about the actual happening than by the handling therafter: Why on earth would you continue your flight to FL 200 and only then realize you have to return? Would they have continued to LAX if they wouldn't have a roll problem?
There might be legitimate reasons why you get a wing touching the surface, but thereafter you do never continue the flight. Period.
This is what frightens me about this AA crew. Haven't they checked their wings after the rotation? Have they thought about keeping the slats out with structural damage?!

TEM advises you create time. As the takeoff actually occured and there was nothing along the lines of smoke, fire or life threatening that required an immediate response, the proper actions would to find a safe place, assess and proceed with the plan.
FL200 is out of the immediate craziness of the terminal area, yet likely not all that far from the airport considering they had lots of gas, airport options, communications to complete and possibly reading to do depending on what if any messages were displayed. Very comfortable with this aspect of the crew's reaction.

[Dani]

FL200 is out of the immediate craziness of the terminal area, yet likely not all that far from the airport considering they had lots of gas, airport options, communications to complete and possibly reading to do depending on what if any messages were displayed. Very comfortable with this aspect of the crew's reaction.

I agree that FL200 is better than crawling along the surface like Ethiopian, but I would rather reduce speed and keep the flaps out. Imagine having a thing big as a house door in your slats and you try to retract them...

[West Coast]

I agree that FL200 is better than crawling along the surface like Ethiopian, but I would rather reduce speed and keep the flaps out. Imagine having a thing big as a house door in your slats and you try to retract them...

If as you describe has occured, it would have been obvious visually or through airframe buffeting.

[Squawk7777]

Be it what it was... - I'm less concerned about the actual happening than by the handling therafter: Why on earth would you continue your flight to FL 200 and only then realize you have to return? Would they have continued to LAX if they wouldn't have a roll problem?
There might be legitimate reasons why you get a wing touching the surface, but thereafter you do never continue the flight. Period.
This is what frightens me about this AA crew. Haven't they checked their wings after the rotation? Have they thought about keeping the slats out with structural damage?!

What about if no damage is visible from the flight deck and the cockpit? I remember posting a thread about an EK flight with rudder damage and odd ECAM advisory messages (or whatever Boeing calls it) from Moscow to DXB a couple of years ago. The majority of contributing pilots argued that if no error message is present it would be perfectly safe to continue the flight. The EK crew made that decision and discovered huge piece of their rudder missing when they landed in DXB.

But after years of reading pprune I realize that most pilots are inferior to certain European ones.

[Squawk7777]

If as you describe has occured, it would have been obvious visually or through airframe buffeting.

Or the opposite could have occurred. Imagine slat damage and suddenly pieces of it tear off.

[ELAC]

Citing AVH,
"According to information The Aviation Herald received on Apr 12th 2019 ground tracks reveal the aircraft was dragging its left wing tip for quite some distance on the ground, the ground tracks even suggest the aircraft came close to ground loop.:eek:

The aircraft and left wing tip became airborne just ahead of the runway sign, the left wing tip impacted the sign, parts of which became embedded in the left wing tip. The wing also sustained according damage to its underside near the wingtip."

“When we departed… strong roll to the left… as we climbed out,” the pilot told air traffic controllers shortly after takeoff, according to an audio recording from LiveATC.net.
“We were banking… Uncontrolled bank 45° to the left.”
“Turbulence from another aircraft?” the pilot adds.
“I don’t think so. There’s a good crosswind, but we had an un-commanded roll to the left as we rotated.”

The pilot also tells controllers that the aircraft was at that point “flying great”, and he requests clearance to return to JFK, where the A321 landed without incident at 21:09.

“" I was aboard this aircraft. The take off was fast, rather quick and felt short. Then we pitched down and banked right (left wing up) and then left (right wing up) and the back felt to skid out sideways, I was in the window seat just behind the left wing. Then it felt like the pilot pulled the aircraft up manually. He continued to make very strong left and right banks while in the air before we circled back to JFK. He made an announcement that we had a major computer failure, but that he had control of the airplane and that we'll be making an emergency landing."

Given this description of the ground track, a prevailing crosswind from the right, the reported crew comments and the reported passenger observations this event could be the result of something similar to what occurred to the Lufthansa A320 D-AIPW in 2001. If a mis-wiring of the ELAC plug fitting is still possible (can't recall if Airbus modified this subsequently) then a reversal of the PF's aileron control could possibly account for what's been observed/reported.

Imagine the PF establishing a small into wind right wing down input when rotating to counter the expected effect of the right wing rising due to what he described as a "good crosswind". A reversed aileron input would exacerbate the crosswind's effect of raising the right wing with the PF responding by adding a further reversed right wing down input causing the right wing to rise further and the left to start dragging on the ground. Increased drag on the left side pulls the aircraft to the left eventually with the tip off the paved surface and contacting the DTG sign just as the aircraft gets airborne. Once in the air the reduction in drag on the left side after the impact with the sign induces an initial roll back to the right mentioned by the passenger followed by further roll oscillations to left and right that would be bound to occur if the ailerons were operating in reverse to the PF's stick inputs. As with D-AIPW a transfer of control to the other pilot or engagement of the A/P would have caused the reversed inputs to cease allowing the airplane to be controlled normally and leaving the appearance to the crew of having experienced an uncommanded roll to the left on take-off (which indeed it would be).

There was also at least one instance of spoiler actuators being incorrectly locked out that led to a similar flight control response on rotation, but in that case the uncommanded roll effect persisted throughout the flight which does not accord with the pilot's statement that the aircraft was subsequently "flying great"..

ELAC

https://aviation-safety.net/wikibase/wiki.php?id=147094

https://www.bfu-web.de/EN/Publications/Investigation%20Report/2001/Report_01_5X004-0_Frankfurt_A320.pdf?__blob=publicationFile

https://aviation-safety.net/wikibase/wiki.php?id=147070

https://assets.publishing.service.gov.uk/media/5422fde4e5274a1314000905/Summary_2-1995_Airbus_A320-212__G-KMAM.pdf

[West Coast]

Or the opposite could have occurred. Imagine slat damage and suddenly pieces of it tear off.


'Could have happened"

Well, that didn't happen. I could also "what if" a scenario from the actions you propose that ended up with the crew lawn darting. They did what they did based off training and the information available to them and landed safely. You can arm chair it and hypothesize any number of outcomes and work towards building a narrative. I'll point to the successful outcome

[Squawk7777]

'Could have happened"

Well, that didn't happen. I could also "what if" a scenario from the actions you propose that ended up with the crew lawn darting. They did what they did based off training and the information available to them and landed safely. You can arm chair it and hypothesize any number of outcomes and work towards building a narrative. I'll point to the successful outcome

That was the point I was trying to make. Too many armchair experts here. All I can say is that I wasn't working the flight, meaning I don't know all the details.

[aterpster]

No out of range for takeoff trim warning on the Airbus?

Anything I flew only had an out-of-range warning for stab trim. I didn't fly the AB.

[PJ2]

Given this description of the ground track, a prevailing crosswind from the right, the reported crew comments and the reported passenger observations this event could be the result of something similar to what occurred to the Lufthansa A320 D-AIPW in 2001. If a mis-wiring of the ELAC plug fitting is still possible (can't recall if Airbus modified this subsequently) then a reversal of the PF's aileron control could possibly account for what's been observed/reported.
. . . .
I have had plug reversals on a hydraulic pump, (A333, green/yellow, #2 engine) and I've also had the stick briefly to the stops in the flare when a crosswind picked up a wing, (A320), but a control reversal would be something we'd likely hear loud and clear about right away, wouldn't it? PJ...

[ELAC]

I have had plug reversals on a hydraulic pump, (A333, green/yellow, #2 engine) and I've also had the stick briefly to the stops in the flare when a crosswind picked up a wing, (A320), but a control reversal would be something we'd likely hear loud and clear about right away, wouldn't it? PJ...

You’d like to think so. But, somewhat ironically, I’ve just now noticed that the story behind the “SXF Runway Blocked” thread is a very similar type of an occurrence and yet it took more than a week before any official findings made it into the public domain, so who knows?

Certainly the more time that passes without an AOT the more you tend to expect a more straightforward explanation than reversed wiring of the ELAC.

Cheers!

[DaveReidUK]

Given this description of the ground track, a prevailing crosswind from the right, the reported crew comments and the reported passenger observations this event could be the result of something similar to what occurred to the Lufthansa A320 D-AIPW in 2001. If a mis-wiring of the ELAC plug fitting is still possible (can't recall if Airbus modified this subsequently) then a reversal of the PF's aileron control could possibly account for what's been observed/reported.

It's hard to imagine any rewiring of plugs going on during a 2-hour turnround at JFK.

[ELAC]

It's hard to imagine any rewiring of plugs going on during a 2-hour turnround at JFK.

If that was the length of the time on the ground I would agree.

[Zeffy]

Aircraft being scrapped?

​​​​​​https://simpleflying.com/american-airlines-scraps-wing-strike-a321/amp/

​​​​​​If the reports are correct, some larger aircraft components will either go back to Airbus or be donated. But the airframe will be scrapped. JonNYC made the claims on July 25 and has since doubled down, saying, “all this seems to be pretty confirmed.”

[Ray_Y]

Still no details what had happened? No interim report? Alas. They'll scrap the incident aircraft before we see analysis progress.

Just imagine the comments if this had happened to a 3rd world carrier..... Just Saying!

Fresh wing strike in pprune do that: 737-banged-up-papua (https://www.pprune.org/rumours-news/634400-737-banged-up-papua.html)

[BFSGrad]

NTSB docket opened 6/14/22.

DCA19LA134 (https://data.ntsb.gov/Docket?ProjectID=99240)

[DaveReidUK]

NTSB docket opened 6/14/22.

Opened a couple of months after the event in 2019; released to the public two days ago.

[FlightDetent]

Unless I mixed the L/R sense on the data plot the crew's handling was as expected with resulting appropriate control surface movements.

What went wrong?

[rnzoli]

The CVR, the crew testimonies and crew interviews are shocking. They really had a near-death experience and even the ramp dude was amazed they made it back alive, after seeing the damage.
And this statement from the captain - still under the influence of the adrenaline rush - is something that Airbus will contest heavily.
yeah well, you know what? we, we, we're just having a conversation about that. # Airbus man. this is the kinda # we don't like about it. you know there's so many computers we don't, we don't know what it # does sometimes.

(Well, at least they had the unexpected behavior on the yaw and roll axes, not on the pitch axis.)

[rnzoli]

the crew's handling was as expected
I find the increasing left rudder pedal deflection (and control surface deflection) from 20:40.29 rather unusal, especially with the steady heading and the nose wheel still on the ground. (i.e., good view on the centerline).
I would expect the left rudder deflection for the crosswind from the right to be decreasing, but here it is increasing to its maximum left deflection (almost to the maximum available deflection) just about the nose gear leaving the ground.
I didn't feel the captain had a good recollection on what happened in those moments (aircraft unexpectedly veering left), and the F/O was not looking outside in those seconds.
The initial reflection of the captain was that the rudder pedal somehow "stuck" to the left, meaning that he wasn't aware of pushing it left, so either something or someone may have pushed it to the left, or the captain being under some sort of illusion of the airplane turning right, which he unknowlingly tried to complensate. Is there any centering force for the rudder pedals that may have become asymmetric?

[FlightDetent]

More eyes, more detail, yes. https://data.ntsb.gov/Docket/Document/docBLOB?ID=13940164&FileExtension=pdf&FileName=final_factual_DCA19LA134-Rel.pdf

I did not realize which plot is the zero line on rudder trace - wrongly assumed the bold one which is 10 deg L, apparently. Now I note with interest the docket, among the usual files, has PDF entries on cross-wind take-off techniques.

Here's a pic with the zero rudder line enhanced:



https://cimg9.ibsrv.net/gimg/pprune.org-vbulletin/2000x1274/qar_plot_033b0c411f185bdaaaaaaf97ff59be2bf4a2b8d1.jpg

[FlightDetent]

The vertical orange line marks the moment of rudder zero position.

The green tick 20:40:35.25 marks peak pedal deflection at the "maximum recovery effort" moment. The pedals are hardwired connected, hence only one readout variable.
Same tick is superimposed at start-of-rolling-motion 20:40:32.25, suggesting there was a rudder input about 90% of physical travel - onside.

Still there's a more interesting moment.
from 20:40:31.25
until 20:40:31.75
When L-sidestick (PF) moves from centre to full R deflection in half a second. Strong hand right there, given the spring forces overcome. Is that a reaction to the developing track divergence (zero roll yet, still on the ground)? Wrong as it sounds, it could be - airplane veers to the donwind, we tilt the stick opposite direction. But watch the rudder - at that very moment the pedal deflection doubles into the downwind side.

Then sidestick is released for a second while the left rudder rudder is kept more than 50% of the travel into the roll.

[waito]

Also took a look at the high res FDR plot

20:40:34 EDT shows WoW Sensor Main Right going to AIR. I will group some FDR evens around that timestamp. Values are read with sort of inaccuracy.

Rwy Mag HDG is 314°

-9 ... -4s:
Rudder between -0 and -10° (left), in sync with pedals

-4s ... -3s:
Rudder starts to exceed -10° (left)
Now HDG soon follows Rudder to left

-3 ..
Left Sidestick moved right 16° and pulled back 20°
Rudder quickly to -16° (left), then only gradually reduced
HDG changes up to 309°

-2s ...
Left Sidestick briefly moved to left -5° then right again 20°
Rudder only relieved to -13°
WoW Nose = Air
Roll (Bank) left up to -4°
HDG changes up to 301°

-1s ...
Right Sidestick had moved Right 20°
Rudder slowly reduced to -10° then runs right to 8° (note the pedal-to-rudder offset)
At time of WoW R Main = Air: Bank is -14° (left)

0s ...
Right Sidestick briefly released to <10° then again Right 20°
Left Sidestick briefly pushed to -3° then pulled again close to 20°
Right Sidestick follows the pull
HDG peaks at 290°
Bank develops to -36°
Rudder develops up to 20° right

+1s ...
Bank max at ~37°

+1.5s: WoW L Main = Air
then Rudder towards neutral
Both Sidesticks Lateral (Bank) towards neutral

+2s ...
Right Sidestick now is completly relased and not used anymore
Left Sidestick goes right then full left again
and is then reduced Longitudinal (Pitch) towards 0°
Rudder around neutral, then start to turn left again
bank reduces from -30 to -7°

+3s ...
Rudder at -20° (left) again
Bank around 0°
HDG 300°
Then Left Sidestick Lat (bank) back to 0°

+4s ...
Rudder back to neutral, then 2s right 10° then neutral for the remainder
Bank changes left to 16°
Left Sidestick moves right to 20°

+5s ...
Bank peaks at -20°
Now Left Sidestick is releived towards lat (bank) 4...0°
HDG ~288°

waito

[FlightDetent]

You chose the reference zero at MLG RH WoW = Air understandably, that is when the bank which developed into the tip scrape begins.

Let me offer somewhat offset view. The ground contact was a terrifying ending of a problem. The bank angle is the second manifestation of the problem, the first being the centerline divergence. The problem is whatever caused that divergence. The dynamics of the banking motion and later ground contact are both in the consequences link of the accident chain.

At 20:40:31.5 the PF attempts a correction (quite wrongly), maybe becasue the aeroplane was observed pointing for a sideways excursion. An interesting moment when the onside rudder probably amplified the situation beyond controllable for this crew. Nevertheless, to my understanding, the 'chain-link zero timestamp' is 20:40:30.

Shame this was not a SE Asian LoCo or CEE ACMI P2F. By now we would be having a very livid discussion about the de-skilling of the pilot out of the profession with many well-researched academic explanations.

One more picture to show why I think 20:40:30 is relevant.

[FlightDetent]

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/463x1186/qar_plot_033b0c411f185bdaaaaaaf97ff59be2bf4a2b8d1_649dc405de 0201bc86630c33a6e7218f885e7f3d.jpg

Notwithstanding the 5° symmetrical aileron droop, everyting is reading 0 except the rudder pedal and the (consistent) surface deflection. Initially needed to keep centeline under crosswind conditions, however at 20:40:30 the airplane starts deviating left. The rudder angle being steady until that point (cropped out), this could be due to increased aerodynamical effectiveness as the airpseed builds up (155 KIAS should be enought to be well airborne even for a heavy A321 BTW, what Vspeeds did they actually calculate?).

That heading deviation is followed by an additional L rudder pedal input while everything else remains perfectly neutral. That is the problem - I don't know what it is but I can see where it is.

Quack :sad:.

[waito]

FlightDetent: My reference point "0 seconds" doesn't hold any importance. It's just meant as a split between takeoff roll and liftoff for orientation. As you show, the issue starts around 4 seconds before that. Why the rudder was moving this way I don't judge. I haven't read most of the files yet.

An interesting note from me for casual readers:

Wind from clearance was 010/17
A321 has a 25° sweepback wing
The heading change was up to 8° per second

When a swept wing plane is yawing left:
right wing accelerates forward into the wind = lift increase
right wing sweep angle reduces relative to airstream (160kn IAS vs. 010/17) = lift increase
left wing vice versa: ... decelerates ... sweep angle increases out of the airstream = lift decrease
within fast left roll, right wing effectivly faces lower AoA = lift decrease, left wing higher dynamic AoA, lift increase

Now I can't do the math obviously and what dominates over what. Let's not forget, countering aileron input was large. But just not enough obviously. By the way, what's the A321 Flight Law / Aileron Strategy in this takeoff phase?

Any mentioning of gusts in the docket? CVR states a 010/17G23 at landing clearence later.

[FlightDetent]

Clear on that. A less understanding reader might focus on the wrong moment, hence I mentioned it.

Without checking the books, at this stage all control should be direct to the surfaces, no FBW magic. Apart from the relationship not being necessarily linear angle to angle that is, it could be electronically 'geared' but still with direct relation to control displacement.

Near full rudder will cause sideslip which comes with profound effect on the relative wing span (also shielding the root area on the leeway side). Guessing these two create the rolling motion the strongest, not any gusts. As you say, the rolling itself has a dampening effect but of a much smaller extent.

A conventional into-the-wind aileron input (not recorded on the trace btw, quack) prevents any undesired roll caused by gust on this dihedral wing. Very little is needed, around 3 deg - a piloting technique required to avoid raising the upwind spoilers.

In other words, as the QAR with a full set of data was immediately available most likely the knowledgeable people formed a very good understanding within 48 hours. Since then:
- no Airbus operational telex
- no bells from the ALPA

[waito]

From the docket - bold is the accident minute at KJFK
https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/624x486/aa300_winds_b6d0da71b9ad548d03450e6549757f92345c340e.jpg

[FlightDetent]

Follow up on the steering:

Ground mode is a direct relationship between sidestick deflection and elevator deflection, without auto trim. [FCOM DSC 27-20-10-20 A]

For roll control during take-off, the transition from Ground Mode blends into to Flight Mode (full FWB magic) over 0,5 seconds after the pitch reaches 8 degrees N.U. Thus anything afer 20:40:34 is roll demand control of the FBW - assuming it is what it actually does (pitch normal law is most certainly not a simple 1g command as the FCOM explains).

More observations:
+ despite full and dual R sidesticks, the aileron deflection is not maximized after Flight Mode becomes active. At 20:40:35 this is understandable, as the roll 1st derivation (not charted) peaks with reversal of the bank. Inbetween secon d 34-35 it is bit more confusing. Maybe the effect of absolute symmetrical deflection being reduced due to tkof aileron droop?
+ seconds 39-40 the aileron displacement is not symmetrical
+ we don't know the impact moment. Assuming it happened at recorded max bank is not correct.

[rnzoli]

+ we don't know the impact moment. Assuming it happened at recorded max bank is not correct.
That's interesting, how can someone find that moment actually? I looked for the ground impact moment as a sudden freeze or reduction of left bank angle, but I didn't find any. The wing damage is also more pronounced on the leading edge, i.e., hitting something sticking out of the ground. Maybe the left wingtip was only grazing the ground surface, without excerting a major force against the left roll.

Any thoughts about the rudder's transition from ground to flight mode?
As the captain reported that the rudder pedal felt "stiff" and had to input a larger than usual left rudder force with his left leg during the ground roll.
This makes me think that the pedals may have "softened up" during those few seconds, and this may have been another reason, why the captain inadvertendly increased the left pedal deflection.
He may have kept pusing the left pedal with the same force as during the ground roll, but the resistence of the pedal decreased unexpectedly, so the pedal deflection increased for a few seconds, before the captain could comprehend the situation and reverse the rudder.

I hope Airbus will not come with the same - and wrong - theory as Boeing did many years ago, when they claimed the pilots mixed up their left and right legs....

[FlightDetent]

It might have been the max bank angle moment, just assuming automatically that is was is not correct.

Rudder has a direct linkage to flight deck and as such to my understanding only has a direct mode at all flight phases. FCOM is sketchy on this one and there is some witchcraft involving the (software) yaw damper. The yaw damper commands (also used for turn co-ordination) are NOT fed back to the pedals.

The personal profile of the S.I.C is not exactly the ordinary, not sure how common that is even in the US.
​​​​​​
For the moment I don't have an answer about the rudder pedals centering mechanism. However, unusual resistance is to be expected if you put unusual amount of it.

15 kts is the standard SIM cross-wind setup, should not be a new encounter to anyone. Reader beware, indeed, the tower reported wind only has a loose co-relation to the actual air mass environment experienced at rotation.

The plane did not strike the ground, God forbid. Only clipped the distance marker which is bad enough. Any such superstructure is frangible by regulation and the collision with 65-ish metric tonne behemoth at 160 knots hardly resulted in marked change in kinematics.

Audio? Not sure over the TKOF engine roar and it is easy to understand the crew had sensory overload just trying to process what they were seeing.

[waito]

+ we don't know the impact moment. Assuming it happened at recorded max bank is not correct.
Start of impact:
Not before Bank Angle exceeded zero at 20:40:32
At which angle depends on compressed strut state of Left MLG
When we assume it's in the 5°-12 region, that gives us a time of start between 20:40:33 and ...34. Only 1 second uncertainty!

End of impact:
Latest when the Bank angle started to reduce, because that will move up the wing tip (instead of the fuselage and right wing suddenly losing height). Maybe it takes a split second to unload the wing tension.
So end of impact around 20:40:35.0...35.5 mark

Duration in the 1 - 2.5s range. Can we narrow it down further?

I'm also looging at the Vertical Acceleration Graph, but can we read something from that?

[waito]

Rudder has a direct linkage to flight deck and as such to my understanding only has a direct mode at all flight phases. FCOM is sketchy on this one and there is some witchcraft involving the (software) yaw damper. The yaw damper commands (also used for turn co-ordination) are NOT fed back to the pedals.

From our position we cannot rule out any erroneous system influence regarding rudder during the takeoff roll. Because the direct link is augmented with the auto-coordination/yaw-damper function.
Not knowing Airbus at all, I wonder what the partial deviation rudder pedals to actual rudder surface FDR could mean. It's not simply a delay.

[waito]

+ despite full and dual R sidesticks, the aileron deflection (...) Inbetween secon d 34-35 it is bit more confusing. Maybe the effect of absolute symmetrical deflection being reduced due to tkof aileron droop?


https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/439x122/aa300_aileron_fdr_23d166b958bcb4f8e8deb490031ee47642139525.j pg

I thought about it. Since it happened in the seconds of the wing impact, the Left Outer Aileron was likely to pressed back. See contact mark on picture.

https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/841x497/aa300_aileron_e05059c08d8805af9767991fc2a968d0e3b2b16c.jpg
When the wing flexed away the aileron took some of the force? So the wingtip contacted earlier, then for a shorter time the aileron? Or was it a momentary impact from the marker alone? But wouldn't this show a sudden pushback and a slow extension of that aileron?

Does FDR show actual hardware position of the outboard aileron at all?

[rnzoli]

Yes, that must have been a moment of wingtip scraping, and it conincides with the moment the right MLG lifted off the ground, but the left MLG still has weight on it.
This means that the force around the longitudinal axis was present already at Vr and banked the aircraft immediately, while the left MLG hasn't even come away from the runway.
I am not sure how it works with this bird> does it have a crossover speed, below which the ailerons are unable to compensate the rolling forces caused by the almost fully deflected rudder surface?
If yes, the question is not why the aircraft rolled, but goes back to the question, why the pedal deflected so much to the left a few seconds before rotation and unstick.

[hans brinker]

So, someone correct me if I am wrong, but the only thing I see is the rudder being deflected to the left, during the ground roll. As they get closer to Vr, this input increases, and later the PF comments that he was almost full left rudder to correct for their left deviation (…????…). Upon rotation with a lot of left rudder it rolled to the left, and (both) pilots put in right stick input, and the aircraft started to roll right, the pilot(s) added right rudder, and the aircraft rolled too far too the right. Eventually the oscilations stopped.
I see nothing the aircraft did that isn’t explained by the inputs the PF made. And his comments to the FA that with the bus you never know what it is doing don’t really help.

[rnzoli]

later the PF comments that he was almost full left rudder to correct for their left deviation (…????…)..
Where did you see THAT comment?

Crew statement:
The takeoff roll was normal up to approximately V1/VR speed, at which time the aircraft began to turn to the left at an alarming rate. I immediately began to rotate the aircraft and we became airborne near the runway edge. At this point, the aircraft seemed difficult to control in both pitch and roll axes. The aircraft rolled left and we apparently struck an unknown object with the left wingtip as we became airborne.

Crew interview
About 130 knots the nosewheel steering was completely disengaged and they can only use rudder to steer the airplane. In other airplanes they would put aileron into the wind but in the A320 series the spoilers would deploy. The technique was to leave the stick neutral and rotate the airplane, once in the air apply some aileron into the wind. He estimated winds were about 60 degrees from the right and they had a 15-knot crosswind component during their takeoff. He kept the aileron neutral until rotation then he added aileron into the wind. He anticipated the need for right aileron and slowly let go of the rudder to establish a crab.
...
He remembered the rudder feeling a little heavy but did not really know why but chocked it up to a stronger crosswind. On the playback he noticed some modulation on the rudder. He was surprised how much left rudder it was taking but at the time he felt the airplane was controllable. At the time he did not see any reason to believe that he would not be able to maintain the aircraft on or near the centerline. It was taking a lot of physical force and energy to hold the rudder during the takeoff roll.

[waito]

but the only thing I see is ...

Mind what you don't see and can't feel, hear, sense. I refrain from premature conclusions.

[hans brinker]

Where did you see THAT comment?

CVR from the docket. 20:46:32.0
INT1"that was a ah full left rudder to keep it on the, on the runway and the ah"

[hans brinker]

Mind what you don't see and can't feel, hear, sense. I refrain from premature conclusions.

So do I. No conclusion was drawn. I asked if my observation was incorrect.

[rnzoli]

CVR from the docket. 20:46:32.0
INT1"that was a ah full left rudder to keep it on the, on the runway and the ah"
Thanks, I see. That comment refers to the left rudder that was necessary to keep it on the centerline during the takeoff roll due to the right crosswind..
It is NOT referring the unexpected left turn just about rotating and becoming airborne.
That part is referred to in the 2nd part of his remaining sentence
and then ah the one- the once we got airborne she just went # tits up

The "tits up" event is when the aircraft made a surprise turn to the left and approched the the runway edge during V1-Vr, as if the right crosswind had been replaced by a crosswing from the left, or, the amount of force necessary to deflect the rudder pedal to the left had decreased significantly, allowing it to be deflected much more than during the takeoff roll - with the same force from the captain's left leg.

[hans brinker]

Thanks, I see. That comment refers to the left rudder that was necessary to keep it on the centerline during the takeoff roll due to the right crosswind..
It is NOT referring the unexpected left turn just about rotating and becoming airborne.

Yes. I fly the A320. You would need a small amount of rudder input for the crosswind that was reported. It looks like they were left of center, and in a left turn on the ground. His statement suggests that he was making the input that caused that. If you rotate holding full left rudder, and again, it looks like he did, a left bank after rotation would be expected. I still don't see anything the aircraft did that wasn't commanded by the pilot.

[tubby linton]

A useful source is in Dsc 27-20-10-10 which shows how the modes change on rotation.When the aircraft is on the ground (in “on ground” mode), the sidestick commands the aileron and roll spoiler surface deflection. The amount of control surface deflection that results from a given amount of sidestick deflection depends upon aircraft speed. The pedals control rudder deflection through a direct mechanical linkage. The aircraft smoothly transitions to “in flight” mode shortly after liftoff.

When the aircraft is in the “in flight” mode, normal law combines control of the ailerons, spoilers (except N° 1 spoilers), and rudder (for turn coordination) in the sidestick. The pilot does not need to use the rudder for turn coordination. While the system thereby gives the pilot control of the roll and heading, it also limits the roll rate and bank angle, coordinates the turns, and damps the dutch roll.

[FlightDetent]

The full pedal delection is about the famous 10 inch.

A recognizable xwind of 15 kts requires about 2 inches, later reducing to about 1. During the final stages before rotation it is pulsating a bit (towards 0) to prevent overcompensation and fighting your own PIO.

​​​​At roatation I get the most consistent and smoothest results by centering everything. Immediately post liftoff the personal de-crab techniques differ.

Last tested 3 hours ago.

The CVR reads to me very clearly. Also the recorded parameters look consistent to tracked inputs on the controls.

To reiterate, I find constant 1 inch (10% of travel) input during high speed borderline excessive.

The plot shows the initial deviation compensated by full into the wind sidestick (which has no effects whatsoever) and a cross-control full rudder eventually, which only worsens the situation and is recored as such.

[rnzoli]

Yes. I fly the A320. You would need a small amount of rudder input for the crosswind that was reported. It looks like they were left of center, and in a left turn on the ground. His statement suggests that he was making the input that caused that. If you rotate holding full left rudder, and again, it looks like he did, a left bank after rotation would be expected. I still don't see anything the aircraft did that wasn't commanded by the pilot.

That's fine, but then it begs another question that maybe you can explain.
We also know that the pilot placed an unusual amount of input force to the left pedal during the early stages of the takeoff roll. (He stated this during the interviews as a "feeling", and he also was surprised about simulation playback later on.)

So in that case, why didn't the aircraft run off the runway earlier?

I find it rather suspicious, that someone is able to keep a fairly steady heading during the takeoff roll, but suddenly mixes up left and right leg just about becoming airborne. .
This sort of left/right mixup theory was already tried (and failed) during the attempts to explain the Boeing rudder reversal accidents in the 1990's. FDR's at that time didn't show the actual rudder deflection, so it was easier to make such a claim, assuming that the rudder pedal and control surface must have moved together. But Boeing's expert was proven wrong., pilots don't mix up left and right legs after a few thousand hours. So "the captain suddenly forgot everything he knew, and mixed up his left and right leg" theory seems very odd again.
By the way, the aircraft never flew again, it was scrapped, which I find a little unusual. Perhaps a PR move from the airline.

[rnzoli]

When the aircraft is on the ground (in “on ground” mode), the sidestick commands the aileron and roll spoiler surface deflection. The amount of control surface deflection that results from a given amount of sidestick deflection depends upon aircraft speed..
I wonder Is there any data about the spoilers in the FDR? I could not find any.

edit: I am curious about that because from the outline of the event, the captain had to input more than usual left rudder to keep the aircraft accelerating on the runway. Why? Maybe:
- much crosswind stronger than expected?
- nose wheel steering slight misalignent?
- asymmetric braking of the main wheel?
- excessive right spoiler deployment?
- ?

I could attribute the event to the pilot's complacency and lack of attention, if the wrong inputs had been provided only during the rotation time period.
With the excessive left rudder input already present during the early part of takeoff rol, I can't help thinking of a right yawing tentency he tried to keep under control, and which disappeared in the moments of becoming airborne.

[waito]

I wonder Is there any data about the spoilers in the FDR? I could not find any.


Modern FDR should record it, but it's neither in the plot not in the tabular "raw" data inside the docket.

[waito]

If you rotate holding full left rudder, and again, it looks like he did, a left bank after rotation would be expected.
I think nobody challenges this anymore. It's quite clear

I still don't see anything the aircraft did that wasn't commanded by the pilot.

So either it's the PF trying to cover up mishandling or ...

the captain had to input more than usual left rudder to keep the aircraft accelerating on the runway. Why?

... any influence yet unknown to us.
​​​​​​​

[waito]

Time,Time Hrs,Time Min,Time Sec,Altitude Press,Accel Vert,Aileron-L,Aileron-R,
Airspeed Comp,Altitude Radio 1,Elevator-L,Elevator-R,Eng1 N1 Act,Eng2 N1 Act,
Gear WOW-L,Gear WOW-N,Gear WOW-R,Heading,Pitch Attitude,Roll Attitude,
Rudder,Rudder Ped,Sidestick Lat-L,Sidestick Lat-R,Sidestick Long-L,Sidestick Long-R

That's in the tabular data. Anything not plotted in the Graph?

[waito]

Brushed up my FDR-to-Excel Skills (it's tough using a non-US-version with its other decimal and time format support.)
Here's higher resolution of the roll and rudder values (right axis, minus=left is up). Only added the WoW as other data so far

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1784x754/aa300_own_fdr_1_4ac95ca60029f29591fcff4683c5eebbd347d102.jpg

[henra]

With the excessive left rudder input already present during the early part of takeoff rol, I can't help thinking of a right yawing tentency he tried to keep under control, and which disappeared in the moments of becoming airborne.
What right yawing tendency? There is a left yawing tendency in the heading starting some time before the main upset. And after this left yaw started left rudder pedal was continously increased to more than twice the deflection (and an enourmous deflection at that) compared to when the left yaw started. There is nothing suspicious in the traces regarding what the aircraft did compared to what the control input was. Only problem is the inputs don't seem to make any sense. I guess we will never really know what the reason for those inputs were.

[rnzoli]

What right yawing tendency? There is a left yawing tendency in the heading starting some time before the main upset. .
The heading reflects the combined result of a yawing tendency AND the rudder surface deflection together.
If you step back from the imminent main upset, and look at the early part of the takeoff roll instead, the pilot already had to input stronger left rudder force than he expected with the wind data. So there must have been an additional right yawing tendency during the early part of the takeoff roll, that he - successfully - compensated with stronger push on the left pedal.

(If there had been no such tendency, the aircraft would have ran off the left runway edge before becoming airborne. But it didn't. Something was causing a greater tendency to yaw to the right than expected, which disappeared around the moment when the aircraft rotated. The continued pressure of the left pedal remained, led to an even greater deflection of the rudder pedals and surface, and the over-compensation of the disappearing-reducing right yawing tendency resulted in a susprise turn to the left and yaw to the left instead, with practically no input force change from the pilot flying.)

The last appearence of that "hidden" right yawing tendency may be between 20:40:26 and 20:40:28. You can see a slight heading deviation to the right, followed by a significant 10 degree left rudder deflection, and a subsequent return to the normal heading. Would be good to understand, what "conditioned" the pilot to input larger-than-usual left rudder forces, because that pre-conditioning may be partially the answer why the deflection increased into the wrong direction at rotation.

[FlightDetent]

I see what you mean. Yes, that 10 deg rudder seem to fix a right deviation back to centre-line. It's almost 2 seconds and markedly larger than normally expected.

The plot is missing LOC deviation to see the lateral offset. Following your line of thinking, another would be the brake pressure for wheels 3&4 and their temperature.

To my experience, without a small aileron input the plane has a tendency to go downwind. And theirs (during the roll) didn't despite the left rudder input.

[waito]

Allright, here Special FDR's from start of T/O roll (FDR tabular data starts at 20:40:00 anyway)
(Edit: replaced Plots with better ones)

Overview:
https://cimg9.ibsrv.net/gimg/pprune.org-vbulletin/1091x792/aa300_own_fdr_2_38f434d6cfb7adceab83bcee4fff7350e76e3937.jpg


Following Plot with Heading in higher range, Rwy Hdg marked with yellow line, Rudder Zero marked with blue line
I reversed HDG here so +y is left turn to match rudder orientation:

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1096x791/aa300_own_fdr_3_db1120a1a639cd180031efe98b1e35ca32cc5442.jpg

[waito]

Especially looking at those new plots of mine,

from 20:40:10 the left rudder peak values show a decreasing line over speed, as we expect.
This is a trend up to 20:40:30, with exception reacting for 2 heading bumps to the right.
Only at and after 20:40:30 this known "violent left push" leading to the mess is outstanding.


Now if a zig-zagging between -5 and -13° rudder in initial roll, then moving btwn -3 and -10° in the later roll is typical on that xwind values, I have no idea.
How much inch of travel is 10° rudder pedals?

engines seem stable
speed has unsteadiness at 4-5 points, looks like going along with those heading variations - gust or wake turbs ... so it was not totally steady air, but also not drastic.
no brake line values, no spoiler readouts to compare a right assymetry

Don't think we find other hard facts from it. But how do I know...

[FlightDetent]

Capt. Occam suggests the mysterious right tendency might just be the cross-wind acting on the empennage after all.

[rnzoli]

The plot is missing LOC deviation to see the lateral offset. Following your line of thinking, another would be the brake pressure for wheels 3&4 and their temperature.
In the interviews, they mention a computer simulation playback of the incident, so I think there will be some more information on the actual deviation from the runway centerline.
And yes, perhaps it was nothing but higher than expected crosswind gusts Captain Occam is often right. It's just good to have all the failure modes on the table, so that we can discard 99% of them with confidence :)

[henra]

Allright, here Special FDR's from start of T/O roll (FDR tabular data starts at 20:40:00 anyway)
(Edit: replaced Plots with better ones)

Overview:

Following Plot with Heading in higher range, Rwy Hdg marked with yellow line, Rudder Zero marked with blue line
I reversed HDG here so +y is left turn to match rudder orientation:

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1096x791/aa300_own_fdr_3_db1120a1a639cd180031efe98b1e35ca32cc5442.jpg


Thank you!
So there was indeed at the beginning on average a relevant left deflection of the rudder while heading was more or less stable and straight. The average Rudder deflection almost linearly decreases from slightly below 10° to around 5° at takeoff speed before suddenly and continuously being deflected to 20°.
Reducing of deflection would match the correction of a cross wind (or the nose wheel not pointing exactly aligned with the rudder, but this would have surely been identified since).

[FlightDetent]

I have measured the deflection in a D-level FSTD. Well, it's not 10 inches. :rolleyes: More like 11 cm.

Thus the 1/2 deflection, oscillating and reducing to 1/3 (5 to 2 cm travel) during the stable roll matches personal experience (post #153)

[BFSGrad]

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The captain’s excessive left rudder pedal input during the takeoff ground roll, which caused a large heading deviation and a left roll upon rotation that resulted in the left wingtip striking the ground.

Also from the NTSB final report:

Further examination of the airplane determined that the left wing had a permanent upward deflection starting about midspan of the left wing, resulting in the left wingtip being about 6 inches higher than the right wingtip.

[waito]

Thank you BFSgrad. I assume the permanent upward warp was the result of the accident, not it's cause.

Summary on AVHERALD (http://avherald.com/h?article=4c68c5a8&opt=0) tells it was no aircraft related issue and I can't see any other influence than the PF excessive left rudder.

It was a 14-17KT crosswind, stronger than wind check from tower suggested, but about half of companys' 35KT xwind limit
comparison with 12 months data of other flights showed less rudder input, even on takeoffs with stronger crosswind
simulation showed that the aircraft reaction was consistent with the input given. Expained the yaw to the left runway edge and the roll during liftoff. So no anomaly, and I guess no other contributing factors
The only anomaly was the aileron deflection during wing scrape (as we found already in the FDR plot), again as a consequence, not cause.


Bad day, and yes, Human factor applying control force without being aware of it.

[waito]

Answer to other questions:

After the accident, American Airlines examined runway 31L and documented a left main landing gear tire mark that was 564 ft long, a right main landing gear tire mark that was 216 ft long, and a scrape mark from the left wingtip that was 323 ft long. The wingtip scrape marks began to the left of the runway edge marking and extended to the edge of the paved surface. The airplane’s left wing impacted a distance remaining marker on the left edge of the paved runway surface

Means the scraping lasted for around 1.25 seconds.

[zambonidriver]

I find it remarkable that they decided to scrap the airframe 🤔

[DaveReidUK]

I find it remarkable that they decided to scrap the airframe.

FlightGlobal reports that the aircraft was left with a permanent deformation midway along the port wing, such that one wingtip was 6 inches higher than the other.

Attempts to buff it out were unsuccessful. :O

[fdr]

Would love to say that there was a technical issue with this aircraft, can't find any justification for that however. The aircraft at all times responded correctly and promptly to the flight crew input.


Countering the stuck spoiler case, the aircraft yaws on the ground to follow the rudder,

"and the rudder is responding correctly to the rudder pedal"
Not so. Sensing rate for the data stream from the 429 bus is 8Hz. The timestamp is common to both data streams for the rudder and pedal.

The data shows that the rudder position appears to be feeding back to the pedals, in what should be an irreversible control system, yet, there are a number of data points that show the opposite, that the rudder has moved before there was a control input recorded. There is the potential for an artifact from the frequency of the sampling, however, there are a number of data points where it is not possible that the control input could have been made in the time to the record of the position that would result in an artifact, where the control is leading the pedal input.

I am surprised to see that in the data. I doubt that a normal person can make a control input that is so fast that it is recorded out of sequence with the following data.

The blue + is the rudder position, the orange X is the Rudder pedal position recorded in the DFDR. This should not be QAR data, so it should have no sampling errors from 429 to 717 or similar, this should be valid data and valid sampling times. In the expanded view below, there is a rational control position that could have a smoothed line on it, per the DFDR analysis done by the NTSB, but then the position of the control surface is preceding the control input, which is not something that should occur. This occurs in the mid acceleration on the runway, and again appears again in the middle of the upset. Is it an artifact? Probably, but it needs to be discounted before the firing squad lines up.

https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/2000x1075/screen_shot_2022_07_28_at_3_39_25_pm_aa5f8e7d52b4d8ce6ab0e6e a83f3e28d845a53ef.png




Can a hydraulic control system feedback to the control input? Normally it does not, however, there are possible internal leak cases that could do that.

Does it look like that happened at the rotate? No, not immediately, however, if and it is a big if, the rudder system was compromised and feeding into the pedals, then how that would show would be dependent on how it has failed. The rudder pedal is fed back the position of the rudder as well, it also does so on both pedals.

It is possible that a rudder issue did actually occur. I doubt it, but the position of the rudder in the middle of the takeoff acceleration leading the recorded pedal position is concerning, and the same happening in the middle of the lateral excursion is also concerning.

Sensor saturation of the pedal, or rudder or both may be in play, but the data suggests a further look could be warranted. Equally, an error in the followup of the hydraulic actuator to the pedal input could be occurring.

All in all, it is an odd bit of data.



https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/1512x946/aa_300_takeoff_roll_03a552bf906ad05c33cd052550050e42c3e5a38c .png

Figure 1: initial take-off acceleration

https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/1368x859/aa_300_rotate_cc16c919909cb91cf7e73de5c15220f41f054905.png

Figure 2: Nod's wild ride

Super quick intervention by the RHS occupant, as in, wow!

https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/1368x855/aa300_landing_1ce582570004ef6c8140350dc0879747b180a011.png

Figure 3: the last revenue landing of this A321

RHS landing. Interesting decision.


https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/1584x750/aa_300_to_toc__6bcc8ad05ae1c14ba61a926bba337f5d32f07ed6.png

Figure 4. LH SSC gets a work out to 20:51

And then the FO does the landing with a damaged "plain". Interesting call.

[FlightDetent]

I'll need to look it up, but there is a mechanical linkage of the pedals to the rudder as per FCOM. Should work both ways, but perhaps introducing some freeplay?

Would Yaw Damper function or just kinematic / aero lag (WTH, on a powered rudder, why?) explain a bit of what you are seeing? I can't really read it at first glance. I don't think there is any FBW filtering / gearing for the rudder at all, save for that Yaw Damer function (which is not fed back to the pedals - so much for a mechanical linkage).

Once I believed the link actually only goes as far as a hydraulic clutch, into the tail assembly, where it interfaces with a closed loop internal servo-booster of the rudder itself.

Otherwise the YD on the bus is underexplained in the FCOM and that is an understatement. But hey what, they need to say steady climb is a constant 1 g path for their audience.

[waito]

I noticed this as well 1 month ago:
Also took a look at the high res FDR plot
...
20:40:33 EDT ...
Right Sidestick had moved Right 20°
Rudder slowly reduced to -10° then runs right to 8° (note the pedal-to-rudder offset)


But now with the final report stating that no aircraft system was a cause, this would rather be a FDR related pecularity. Whatever, no undetected anomality influencing the events.

But keep digging, it's a funny detail.

[hans brinker]

Would love to say that there was a technical issue with this aircraft, can't find any justification for that however. The aircraft at all times responded correctly and promptly to the flight crew input.


Countering the stuck spoiler case, the aircraft yaws on the ground to follow the rudder,

"and the rudder is responding correctly to the rudder pedal"
Not so.
The data shows that the rudder position appears to be feeding back to the pedals, in what should be an irreversible control system, .

I won't even try to dispute the technical part of your analysis. Having said that:
- The captain was (most probably) the only pilot with feet on the pedals.
- Those pedals ended up deflected to the left.
- The airplane turned to the left, and after rotation banked to the left.
- The captain commented the aircraft banked left, but not did comment the rudder pedals deflected uncommanded.
And while I cannot understand how a 20K hour pilot can make such a basic mistake, I feel it is more likely than a failure leading to an uncommanded input that wasn't recognized by the pilot.

[FlightDetent]

Is not the aileron a give-away? When the heading starts to diverge, there is almost full counteracting stick. And just as you would in a cross-controlled slip landing to keep aligned, even more downwind rudder follows.

40:31 until 40:32,5 on FIGURE 2 from fdr. With the aircraft still on the ground, there is no corrective effect coming from the aileron deflection and the rudder makes the deviation worse. Once pitched up the effective span difference of the swept wing rolls the plane

The stick is back at neutral for rotation while the rudder input remains until after airborne.

[punkalouver]

Interesting that this is not the first AA Airbus departing JFK damaged by the pilot’s excessive rudder pedal input.

[FlightDetent]

Waistline?

[fdr]

I won't even try to dispute the technical part of your analysis. Having said that:
- The captain was (most probably) the only pilot with feet on the pedals.
- Those pedals ended up deflected to the left.
- The airplane turned to the left, and after rotation banked to the left.
- The captain commented the aircraft banked left, but not did comment the rudder pedals deflected uncommanded.
And while I cannot understand how a 20K hour pilot can make such a basic mistake, I feel it is more likely than a failure leading to an uncommanded input that wasn't recognized by the pilot.

I would absolutely agree with you, however, there are pesky data points that are out of order and that may be an artifact, but do not appear to be so, and if they are not an artifact, then there was a potential back drive of the surface to the rudder pedals. Should not happen, but then many things should not happen yet do. Other than that set of data points, I would be suggesting this is a crew cognitive error, but then, there are these pesky data points....

If someone has a rational explanation for that, I should be happy. Without a rational explanation that determines they are artifacts "I am troubled".

Low-frequency sampling can throw up artifacts, but the rate of input change needed to achieve such a sampling rate artifact would be somewhat beyond my creaky bones nowdays, faster than landing a Pitts S1, or downwind hover taxi of an R-22... all usually fun for tap dancing. Rough order, the guys feet would be moving between the 8Hz data points sufficient to get the surface recorded at a place that is then nowhere near the next sample of the pedal position. That is a 2-3" amplitude reversal at around 2 times sampling rate or 16Hz or so. Even Gregory Hines would have issues doing that for the Ethiopian Shim Sham Sand Dance... james Devine may be able to do it, he can get 38 taps per second out, which is toe/heel, and 2 feet, which is around 8.5Hz then.... so, there is some odd data there.

Shim Sham Sand Dance

[WideScreen]

Would love to say that there was a technical issue with this aircraft, can't find any justification for that however. The aircraft at all times responded correctly and promptly to the flight crew input.


Countering the stuck spoiler case, the aircraft yaws on the ground to follow the rudder,

"and the rudder is responding correctly to the rudder pedal"
Not so. Sensing rate for the data stream from the 429 bus is 8Hz. The timestamp is common to both data streams for the rudder and pedal.

The data shows that the rudder position appears to be feeding back to the pedals, in what should be an irreversible control system, yet, there are a number of data points that show the opposite, that the rudder has moved before there was a control input recorded. There is the potential for an artifact from the frequency of the sampling, however, there are a number of data points where it is not possible that the control input could have been made in the time to the record of the position that would result in an artifact, where the control is leading the pedal input.

I am surprised to see that in the data. I doubt that a normal person can make a control input that is so fast that it is recorded out of sequence with the following data.

The blue + is the rudder position, the orange X is the Rudder pedal position recorded in the DFDR. This should not be QAR data, so it should have no sampling errors from 429 to 717 or similar, this should be valid data and valid sampling times. In the expanded view below, there is a rational control position that could have a smoothed line on it, per the DFDR analysis done by the NTSB, but then the position of the control surface is preceding the control input, which is not something that should occur. This occurs in the mid acceleration on the runway, and again appears again in the middle of the upset. Is it an artifact? Probably, but it needs to be discounted before the firing squad lines up.

Can a hydraulic control system feedback to the control input? Normally it does not, however, there are possible internal leak cases that could do that.

Good catch. Strange, this got unnoticed with the investigation.

To me, this looks like the hydraulic accumulator(s) got depleted, due to the extreme high flow/volume requested because of the excessive rudder application. Once the accumulator is depleted, the rudder will no longer rapidly follow the rudder pedals (only at the rate the hydraulic pumps are able to deliver). There is no longer enough hydraulic energy for the rapid "extra" rudder deflection, nor for a forced "return to neutral (or opposite deflection)". And just a few seconds later, without heavy rudder inputs, the accumulator(s) got boosted again, and the sloppy issue is over.


Does it look like that happened at the rotate? No, not immediately, however, if and it is a big if, the rudder system was compromised and feeding into the pedals, then how that would show would be dependent on how it has failed. The rudder pedal is fed back the position of the rudder as well, it also does so on both pedals.

It is possible that a rudder issue did actually occur. I doubt it, but the position of the rudder in the middle of the takeoff acceleration leading the recorded pedal position is concerning, and the same happening in the middle of the lateral excursion is also concerning.

Sensor saturation of the pedal, or rudder or both may be in play, but the data suggests a further look could be warranted. Equally, an error in the followup of the hydraulic actuator to the pedal input could be occurring.

All in all, it is an odd bit of data.

......
I certainly can understand that a rudder, not following the pedals, feels like driving a bicycle/motobike/car with partial flat tires....

Not to say, the ailerons/spoliers may have become sloppy too, given these are having the pressure benefit from the same accumulators.

Q: Do rudder, elevators, ailerons and spoilers use all the same accumulator or are the 3 hydraulic systems working in parallel ? The latter would imply, all accumulators were depleted at the same time.

All in all, it could very well be, the captain was right about the "malfunctioning" of the rudder/ailerons, IE operating in unknown territory, though he did cause this issue himself. The handling transfer to the other side was a decision correct for the malfunctioning experience he encountered.

[fdr]

On hydraulics, the sizing of hydraulic supply has considerable reserves of volume for operations, [§25.1435(c)], separately, Subpart C covers loads but not rates.

Back a ways the AS350 had a nasty little habit of having a jack stall in one particular manoeuvre... another helicopter on one occasion happened to return back to the manufacturers ramp after a funny, which distorted the rotor blades, the company owner being the driver. Hydraulics can have anomalies, but in this case, my concern is that there is a curiosity in the data, the full data set should exist still and could provide some further insight into whether this was an artefact or a control anomaly.

Q: Do rudder, elevators, ailerons and spoilers use all the same accumulator or are the 3 hydraulic systems working in parallel ? The latter would imply, all accumulators were depleted at the same time.

Each of the 3 systems have accumulators, and a priority valve prioritises flight control supply over all other services. there are also had fuses that could cause anomalies to supply volume. The data should readily show transients, but the data in th public docket is an inadequate subset to assess deeper. All 3 systems, green, blue and yellow, power the rudder by recollection on that bus. A single transient would likely not result in an anomaly of much note, but more could become an issue, and could be latent. This is a wild card but the data suggests that there is a funny that should be explained. Weird stuff doesn't just happen to marines.

[spornrad]

... the position of the control surface is preceding the control input, which is not something that should occur. ...

Couldn't it simply be that the pilot let the rudder pedal go, the rudder is blown back towards center and the pedal position is now following the rudder? (with a sub-second delay)
(simple fly-by-steelwire PPL here, no clue about big kite hydraulics)

[WhatShortage]

Couldn't it simply be that the pilot let the rudder pedal go, the rudder is blown back towards center and the pedal position is now following the rudder? (with a sub-second delay)
(simple fly-by-steelwire PPL here, no clue about big kite hydraulics)
Pedal position does not follow rudder position, it's the other way around. If there's hydraulic pressure rudder will be kept neutral if pedals not touched.

[spornrad]

So when the pilot lets the pedal go, rudder being centered, pedals stay deflected? Don't think so...
(Edit: learned there is a conventional mechanical link between pedal position and rudder PCU in the A321. So rudder following pedal and vice versa, both ways.)

[FullMetalJackass]

It appears it was in fact a aircraft malfunction. More will come out in the next few days.

You mean like Air France flight AF11 where control issues on final to CDG were also due to an aircraft malfunction? Right...... I'm more inclined to believe either the Pilots had something incorrectly set up or failed to react to the conditions they were experiencing....

[slast]

Don't know if this final report from a couple of months ago has been mentioned before. An American Airlines A320 at JFK, April 2019. Aircraft understoodf to have been scrapped due irreparable damage to wing structure - left tip bent approx 6ft higher than right.
https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99240/pdf; summary here Accident: American A321 at New York on Apr 10th 2019, wingtip strike and collision with runway sign during departure (avherald.com) (https://avherald.com/h?article=4c68c5a8)
There's an interesting recreation of it here.The first "cover image" shows the wrong wing in contact wiht the ground though. I have no idea how respected the creator "mentour" is but he seems well informed.
WHY did This Aircraft Suddenly ROLL OVER?! American Airlines flight 300 - YouTube

[fdr]

So when the pilot lets the pedal go, rudder being centered, pedals stay deflected? Don't think so...
(Edit: learned there is a conventional mechanical link between pedal position and rudder PCU in the A321. So rudder following pedal and vice versa, both ways.)

Kind of.
The PCU may lag the rudder pedal slightly, however what it won't do is lead it. That is the "funny" in the data. The data rates are fast enough that it is not likely but not impossible that an extremely rapid input and reversal occurred, but of all of the control axis, the rudder is the most unlikely to have that occur, our legs just don't dance that fast (Fred Astaire, we ain't)