
AA A321 takes off after smashing ground sign at JFK - howard941
http://avherald.com/h?article=4c68c5a8&opt=0
======
cmurf
The avherald reporting is better. And has photos of the damage. Currently
they're calling this an accident, not an incident, and per 49 CFR 830.2 that's
because of the substantial damage to the wing.
[http://avherald.com/h?article=4c68c5a8&opt=0](http://avherald.com/h?article=4c68c5a8&opt=0)

A passenger, who they confirmed was on the flight, says the pilot announced "a
major computer failure".

The runway heading and wind conditions mean a crosswind takeoff. The plane
would have a natural inclination to weather vane toward the wind (yaw right)
and the right wing to have more lift (roll left). Proper crosswind takeoff
counteracts this with right aileron and left rudder and slightly higher
rotation speed. The left wing should have lifted sooner, not later, the idea
being to bank into the crosswind to keep the airplane from drifting; and as
the plane lifts off immediately establish a crab into the wind which then
permits wings level flight and climb out while compensating for the cross wind
in order to maintain a runway heading ground track. Anyway, the exact opposite
happened.

I'm not sure which surprises me more, pilot error or computer error. Both seem
incredible to me, and this report is eyebrow raising. Dragging a wing on
takeoff is extremely dangerous, regardless of the frangibility of airport
signage.

~~~
mc32
It looks like another plane’s jet blast from a 90 degree angle could be a
possibility causing it to veer while taking off.

[Speculation by poster Trixie on avherald]

~~~
cmurf
From where? Takeoff runway is 31L, reportedly from intersection KE, therefore
04L isn't a factor, and it puts rotation around intersection PA. No one is
going to be at takeoff power over there and not on a runway. Idle power
wouldn't do this.

If there's an uncommanded roll before V1, I'd expect aborted takeoff. So it's
more plausible this happened after V1, and before Vr, which means the
instigator was present for some distance.

~~~
FPGAhacker
From a comment on avherald:

> It is being discussed at American that as the aircraft was at rotation, JFK
> Ground had cleared a heavy jet into the ramp and he used a great deal of
> power to get moving. His jetblast, coming from a 90 degree angle to flight
> 300 on takeoff, is being considered a factor in the roll of the Airbus as it
> lifted off causing the displacement from the runway and the wingtip drag.

> Powerful taxi thrust could most certainly be an factor. Many years ago I
> witnessed a DC-10 literally blow a small aircraft up and onto its nose, then
> onto its back during landing with the thrust of those DC-10 engines powered
> up while exiting the runway and turning 180 degrees.

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tyingq
Scroll down to these pictures:

[https://www.pprune.org/rumours-news/620410-aa-a321-takes-
off...](https://www.pprune.org/rumours-news/620410-aa-a321-takes-off-after-
smashing-ground-sign-3.html#post10450077)

Youch. It took quite a bit of that sign with it.

------
leemailll
Found this first on vasaviation
([https://www.youtube.com/watch?v=Ca-0Bi2lZhg](https://www.youtube.com/watch?v=Ca-0Bi2lZhg)),
which focus on atc communications. It looks like the pilots took 5 mins to
report to atc for emergency landing request.

~~~
jdsully
I'm surprised we don't keep video of all take offs and landings. Doesn't seem
like it would be overly expensive.

~~~
pintxo
Continuous video surveillance on 3-4 km of runway, from multiple angles, with
night vision support, working 24/7? Might not be impossible, but surely not
cheap.

~~~
jdsully
I watch landing and takeoff videos frequently on YouTube from only one angle.
The lenses are quite large and depth is very compressed but it’s sufficient to
understand a lot of things relevant to an accident.

Daytime only would still be a huge improvement.

------
lvs
The NTSB seems to get a lot of work.

[https://twitter.com/NTSB_Newsroom](https://twitter.com/NTSB_Newsroom)

~~~
consumer451
Thanks for that well of information.

This highway crash[0] makes me feel like it's crazy that we still haven't
created, and mandated, forward collision avoidance for all tractor-trailer
sized vehicles. The people in the SUV never had a chance.

[0]
[https://www.ntsb.gov/investigations/AccidentReports/Reports/...](https://www.ntsb.gov/investigations/AccidentReports/Reports/HWY18FH015-preliminary-
report.pdf)

~~~
jdsully
Trucks are cut off in traffic extremely frequently. Some trucks do have auto
braking and it getting triggered all the time from jerks on the road is a
frequent complaint.

That said the NTSB has recommended it be mandatory.

~~~
consumer451
> Trucks are cut off in traffic extremely frequently. Some trucks do have auto
> braking and it getting triggered all the time from jerks on the road is a
> frequent complaint.

Yeah, false positives would be a giant source of friction. Do you know what
types of sensors the existing systems use?

~~~
jdsully
Nope no specific knowledge, just a decent amount of trucker griping. The
stopping distance of trucks is much longer so the triggering distance on these
devices must be correspondingly longer as well. A lot of cars don't even
realize they cut off the truck because they can stop so much faster.

A trucker can assume that a car cutting them off with open road in the front
won't slam their brakes. These devices can't.

------
pascalxus
I'm confused as to why there would be a sign anywhere near the flight path of
an airplane.

~~~
tyingq
It's a runway marker sign. They are pretty low, and in the grass, and have
breakaway mounts. This sort of thing:
[https://blog.klm.com/assets/uploads/2015/08/Signs_7.jpg](https://blog.klm.com/assets/uploads/2015/08/Signs_7.jpg)

The aircraft would have been way off center of the runway, with the left wing
literally dragging the ground.

JFK runway 31L is 200 feet wide, an A321 has a wingspan of 112 feet. The wings
are 12 feet from the ground at the fuselage, and maybe two feet higher than
that at the wingtips. The photos[1] show heavy abrasion under the left
wingtip, presumably it was dragging the ground.

[1] [https://imgur.com/a/rKu8cUC](https://imgur.com/a/rKu8cUC)

~~~
mveety
Also if there’s wind and the gas in the shocks is a bit low you can easily hit
them.

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userbinator
This is the AVherald article about it, with more details:
[http://avherald.com/h?article=4c68c5a8&opt=0](http://avherald.com/h?article=4c68c5a8&opt=0)

~~~
dang
Ok, we've changed to that from [https://www.pprune.org/rumours-
news/620410-aa-a321-takes-off...](https://www.pprune.org/rumours-
news/620410-aa-a321-takes-off-after-smashing-ground-sign.html).

------
throw03172019
Expensive accident. Glad everyone is safe!

------
kerng
Does this mean the plane "rolled" slightly to the left while still on runway,
and hence the left wing was able to hit that sign? Did the pilot use the
ailerons while on runway?

~~~
cmurf
Unverified video taken on the ground after landing.
[https://www.airliners.net/forum/viewtopic.php?f=3&t=1420137#...](https://www.airliners.net/forum/viewtopic.php?f=3&t=1420137#p21273103)

It looks similar to other photos, and if authentic yes it suggests a
significant roll to the left. From the available information I can't assess
whether the plane was on the ground or airborne, either are possible.

Aileron is normally used for crosswind takeoffs, to lift the leeward wing
sooner in order to "lean" the plane into the crosswind to keep the plane from
drifting from runway centerline. Essentially the opposite happened in this
case. The airplane must have both drifted to the left of the runway center
line (not out of the ordinary, in particular if it's gusty) as well as left
wing dipped.

It's possible this was a suddenly gusty takeoff. I'm not sure to what degree
A320 series can do auto takeoff or computer assisted takeoffs, and what
crosswind limits they presumably have where a pilot has to do the takeoff
manually instead. Maybe the pilot's suggestion of a computer problem is
related to that, and they subsequently took manual control.

~~~
danaliv
_Aileron is normally used for crosswind takeoff_

Airbus crosswind takeoff recommendation is no lateral stick input. The
sidestick is a rate controller, so a lateral deflection commands a roll, not a
specific control surface position like on non-fly-by-wire aircraft. And you
run the risk of deploying spoilers.

~~~
cmurf
The original article article URL before the change to avherald contains a post
that addresses this:
[https://www.pprune.org/showthread.php?p=10450572](https://www.pprune.org/showthread.php?p=10450572)

Obviously we'll have to wait and see what the actual story is, whether this is
really old bad tribal knowledge, and if the operating manual contradicts that,
and whether pilots are getting the proper training and consistently applying
it in practice.

I'm an opinionated and biased pilot and former flight instructor, but not an
aerodynamic engineer. Spoiler extension does not increase the effective angle
of attack of the wing, whereas a dropping aileron does. And therefore off
hand, and without benefit of an Airbus type rating, I don't really care if the
actual control surface is a bit of right spoiler instead of left (down)
aileron, all I care about is that the windward wing does NOT lift off first
because that will foul up the ground track on takeoff, and that's simply not
proper technique.

~~~
danaliv
I'm not typed either, for the record. Current flight instructor and my boss is
a check airman at a major--that's about all I've got to offer. :) As I
understand it there's a potentially dangerous pitch-up moment that occurs if
the roll spoilers deploy on takeoff. (Don't ask me why!)

