
Air India Express 737 Hits ILS, Damages Wall on Departure, Flies for 4 Hours - sassyboy
https://www.flightradar24.com/blog/air-india-express-737-hits-ils-damages-wall-on-departure-flies-for-4-hours-before-diverting/
======
justboxing
Just saw the pics of the damage on the twitter thread linked-to in the
article. See below.

[https://twitter.com/shukla_tarun/status/1050595274869993474](https://twitter.com/shukla_tarun/status/1050595274869993474)

Looks quite severe.

I'm impressed the plane flew for 3 hours without getting destablized and
crashing....

Air India has the worst safety reputation in India, and several accidents /
incidents. I flew Spice Jet a few times over the last few weeks when I was
there visiting. Spice Jet is like India's Virgin America. Service was
excellent and I did not experience any issues while flying.

~~~
nitinreddy88
The most surprising part is, trichy to mumbai takes hardly 1hr flight time.
What caused them to take 4hrs?

In 4hrs, they could have landed in Dubai itself easily

Being Indian, I agree with statement about AirIndia. I would never fly in
AirIndia even if the ticket price is too low, laughably they usually cost way
above than any other competitors.

~~~
jayalpha
"Being Indian, I agree with statement about AirIndia. I would never fly in
AirIndia even if the ticket price is too low, laughably they usually cost way
above than any other competitors."

Since I have flown with Air India, would you mind being more specific? Are the
statistics? My flights were okay. Okay, zero status miles credited at Star
Alliance and a bit stingy with alcohol on board. But food and service was
good, plane looked well maintained.

Please tell me more.

~~~
distant_hat
I used to be a government employee and was required to fly Air India so I flew
it a fair bit. Personally, the flying bit was not that different from others.
Their website was a nightmare to book on, usually I found them generous with
alcohol on international flights, but sample size is small here. Their miles
were hard to use, too many conditions. Staff was a bit low on professionalism.
Saw a couple of fights between flight attendants.

~~~
dsfyu404ed
> Saw a couple of fights between flight attendants.

In flight entertainment.

------
rhn_mk1
I hate articles introducing three-letter-mysteries and leaving the readers in
confusion. To add insult to injury, none of the comments seem to acknowledge
that the topic is impentrable.

What is the mysterious ILS that was hit?

Even after reading the Wikipedia article, I only have a vague idea - seems to
be a radar system, both on ground and in the air. Did the plane hit a radar
tower?

~~~
danaliv
Others have noted that ILS stands for Instrument Landing System. It’s a system
used for landing airplanes when you can’t see the runway, typically getting
you down to 200 feet, but with special training and equipment you can get down
to 100 or even zero (autoland). ILS is the world standard for getting
airplanes onto runways in bad weather.

The ground portion of an ILS consists of two antenna arrays, one at the end of
the runway called the localizer, and one just off to the side called the
glideslope. These arrays produce two fan-shaped signals that vary left-to-
right and up-and-down in such a way that an aircraft can determine its
location relative to the runway with remarkable precision. The localizer
signal provides lateral guidance to the runway centerline, while the
glideslope provides vertical guidance down to the touchdown zone, usually on a
3° glidepath. One or both of these arrays is what this airplane ran into.

The system is passive, in that the signals are simply broadcast from the
ground continuously, aren’t unique to a particular aircraft, and there is no
return or response from aircraft. The ground antennas simply “shout into the
void” as it were, and aircraft receivers determine their location based purely
on the shape of the signals at the aircraft’s location in space.

For illustration here is a localizer antenna (though note that the airplane in
this picture is “backwards,” i.e. the localizer for a given runway is at the
far end of the runway, though it is possible to “fly the backcourse” and land
with one at the near end):
[https://image.slidesharecdn.com/instrumentlandingsystemils-1...](https://image.slidesharecdn.com/instrumentlandingsystemils-140507064050-phpapp01/95/instrument-
landing-system-ils-6-638.jpg?cb=1399444891)

And here is a glideslope antenna:
[https://i.pinimg.com/originals/8f/56/b3/8f56b3b52fb9b81c84f7...](https://i.pinimg.com/originals/8f/56/b3/8f56b3b52fb9b81c84f7f883cbc3d301.jpg)

~~~
avip
Another one of these comments that make this forum always a joy to read.
Thanks for the detailed walkthrough.

------
14
I have been trying to go over how this could happen. The damage to the wall
seems so severe that I would image even over the sound of the engine the pilot
would hear and notice that they had hit a wall. Flying the plane at this point
would be risking their life. The first thing that came to my mind was the only
reason a pilot would risk his life is if his life was already at risk and if
he had been drinking when he hit the wall he would face many year in jail I
assume for putting lives at risk. In a panic says to himself the plane is
damaged but I know it can still fly and takes off without a plan really but
perhaps just to let the alcohol he had leave his system. I hate to speculate
here on HN. This is just crazy to me and I really look forward to hearing more
details as to how his happened.

~~~
captain_perl
After V1, the accelerate-stop distance, the pilot is committed to continue
flying.

The cargo area of most airliners is not pressurized, so the gash is not an
immediate problem.

In a case like this, the pilots would want to climb to several thousand feet
and evaluate the situation before landing.

Looks like the pilot did a great job once it was realized the airplane was
damaged of remaining calm and flying the airplane.

~~~
sandworm101
Cargo is definitely pressurized. Not heated/aced, but pressurezed the same as
the rest of the cabin. Everying from the skin inwards is under 5000ish feet of
pressure.

~~~
Johnny555
It's heated above freezing too as far as I know, I've never had anything in my
luggage freeze.

~~~
sandworm101
Heated in that the air becomes warmer as it is compressed. But not the
additionally-heated air provided the main cabin. Even so, at low air density
even -30 would take a while to cool the large mass of bags.

------
nutcracker46
Who wants to wager that the pilots did an aviation version of the five stages
of grief, with some help from passenger / flight attendant reports?

FO: Tower said we hit something, may have damage. Capt: Just close, we'll be
okay. FA: We heard a thump, and so did the passengers. CA: Just a noise, we'll
be okay. Dispatch on ACARS: You hit the localizer and wall past the far end,
you morons. Descend, lower your cabin diff pressure, and GTF to Mumbai. CA:
How do we explain this? FO: Ask the passengers for newspapes, we must find new
jobs..

~~~
FabHK
Not inconceivable that they decided to keep flying to overwrite the CVR
(assuming it was the old 120 minute type).

Given the apparent structural damage, that was a risky decision.

------
mbell
Unless I'm misinterpreting the satellite image its ~150m from the end of the
runway to that wall[0] and it also looks a bit downhill from the runway to the
wall[1].

I don't see how this could happen without the pilots noticing; they would have
been skimming the ground well past the end of the runway.

[0]
[https://www.google.com/maps/place/Tiruchirapalli+Internation...](https://www.google.com/maps/place/Tiruchirapalli+International+Airport+TRZ/@10.7652872,78.705696,232m/data=!3m1!1e3!4m5!3m4!1s0x3baa8b30609d9727:0xa2f4f10a6d8add6c!8m2!3d10.7603678!4d78.7088693)

[1]
[https://twitter.com/shukla_tarun/status/1050581391828836352](https://twitter.com/shukla_tarun/status/1050581391828836352)

~~~
kijin
Perhaps they were slightly airborne, like 0.5m above the ground, but ground-
based instruments recorded the plane as still being "on the ground" (i.e. same
altitude as the runway) because of the downhill slope? If they really were on
the ground, the pilots would have continued to feel the vibration of the
wheels against the ground, a very clear indication that they aren't flying.

I'm even more surprised that the plane could land on its own wheels despite
the huge gash in the fuselage. Do landing gears retract so quickly, or was the
wall simply not wide enough?

~~~
sokoloff
I have no first-hand information, but I think this is going to turn out to be
a reduced thrust takeoff with the crew being unaware of that (meaning they
screwed up).

Airliners have enough power to lose an engine at a decision speed (V1) while
still on the runway and _on the one remaining engine_ continue to accelerate
on the runway to rotation and eventually liftoff speed and still clear
obstacles. There is no mention of an engine loss causing this issue (and
surely the airplane wouldn't launch for FL360 with one engine INOP), so this
almost has to be a mis-set takeoff thrust accident as, with both engines set
for proper takeoff thrust, it's rare to use more than 2/3 of the runway and
the initial climb is brisk due to the large excess of power a turbojet engine
has at sea level.

------
nmstoker
Question for professional pilots here: does this feel like normal behaviour
for a pilot?

From my limited experience of pilots, this seems entirely unlike the kind of
behaviour you'd expect - they're usually conservative when it comes to safety
or is that just the projected image to reassure the public?!

~~~
unionemployee
Unfortunately don’t have time for a long post at the moment, but as an airline
pilot and instructor/check pilot, I can say that extreme incompetence exists
in the airline world, especially in Africa, India, SE Asia. There could be
some very good reasons that they chose to continue, and often I learn those
reasons when the facts are released, discovering that a good decision was
made. I’ll be following the investigation, but this one seems somewhat
alarming to me. Here’s another of mind-blowing incompetence, also from India -
[https://www.ajc.com/news/national/airliner-forced-land-
after...](https://www.ajc.com/news/national/airliner-forced-land-after-pilots-
accidentally-leave-landing-gear-down-for-entire-
flight/YCu3nXWUl3367aYfQHffMJ/).

Also, more automated, single-pilot/ground operated or pilotless aircraft can’t
come soon enough.

~~~
ksec
\--I can say that extreme incompetence exists in the airline world, especially
in Africa, India, SE Asia

including Hong Kong?

~~~
FabHK
Cathay has a pretty good reputation, I believe. The HK civil aviation
authorities, so-so, but all right. Struggling to get the expensive new ATC
center to work.

(Note that HK is considered part of East Asia.)

~~~
FabHK
Self-reply to add:

See here for some news articles on the ATC centre:

[https://duckduckgo.com/?q=HK+atc+site%3Ascmp.com](https://duckduckgo.com/?q=HK+atc+site%3Ascmp.com)

------
userbinator
The AVherald article:
[http://avherald.com/h?article=4bedd321&opt=0](http://avherald.com/h?article=4bedd321&opt=0)

As some of the others have mentioned, the reason the plane survived is likely
because that was not a pressurised area. If it had breached the pressure
vessel they would've noticed it very quickly (lack of pressurisation).

~~~
InTheArena
Not really - If there had a been a gash in pressurization, they would have
caught it on the way up. The 737 is a _tank_. It has more or less the same
wing load as a F-16. It takes a lot to shake around - it's every bit the 1950s
build 707 chassis, and like the old 50s lathe - it can take a hit and keep
going.

~~~
wahern
Plenty of 737's have had explosive depressurization with injuries or
fatalities, most recently this year

[https://www.bbc.com/news/world-us-
canada-43818752](https://www.bbc.com/news/world-us-canada-43818752)

and one of the most famous incidents (in the U.S.)

[https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243](https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243)

Both were from fatigue, but fatigue doesn't have to be a gradual thing; it
could come from a single hit that causes the pressure vessel to fail at
altitude.

See the whole list here

[https://en.wikipedia.org/wiki/Uncontrolled_decompression#Not...](https://en.wikipedia.org/wiki/Uncontrolled_decompression#Notable_decompression_accidents_and_incidents)

~~~
TylerE
The difference is that happens _at altitude_. When the plane has just taken
off there is no pressure differential. There’s no energy TO explode.

~~~
wahern
Damage can be less severe than an actual puncture of the pressure vessel.
Damage can _weaken_ the pressure vessel such that it only fails (possibly
explosively) once under pressure.

------
gefh
Impressive resilience by the airframe. Good job Boeing.

~~~
yborg
Yes, I'd say this incident makes for a good Boeing ad - "Even a brick wall
can't stop a 737 from flying a route!"

~~~
p1mrx
That seems mildly irresponsible. "Eh, I don't need to pull up, it's a Boeing."

------
basicplus2
Lets hope they scrap that aircraft..

i could not find a reference but i remember an incident where an aircraft only
scraped its backend on take off and repairs were made, but years later the
aircraft was lost with everyone on board after cracks propagated up and around
and the aircraft lost its whole tale section

~~~
aaronmdjones
Those incidents (CAL611, JAL123) only happened because the repair was
completed _improperly_ to begin with and subsequently _missed_ by every
inspection.

There's no reason the aircraft can't be properly repaired, and be as strong as
it was when it was delivered. The Boeing Structural Repair Manual is very
precise. It was just ignored.

~~~
AdrianB1
The problem here is that the plane climbed risking catastrophic
depressurization - you cannot repair in flight, you need to land first for
that.

~~~
azernik
GP was proposing scrapping the aircraft, which is _not_ necessary for ground
repairs.

------
outside1234
Yet another reason not to fly Air India, just in case you needed another
beyond price, on-time performance, service, and cleanliness.

------
nutcracker46
It wouldn't be the first time a crew errs in calculating their takeoff
performance and uses too low a thrust or flap setting. Everyone on that plane
is lucky to be alive, as others have died after similar takeoffs.

~~~
dorfsmay
Too low a thrust?

I thought that on airliners pilots input runway length, altitude and wind
strength and direction, and the computer optimized the thrust accordingly?

~~~
dingaling
Yes, the autothrottle commands the thrust as calculated for a Flex take-off.
But it's only correct if the input parameters are correct. There was a Sunwing
737 which bent the runway lights at Belfast in 2017 because the pilots had
entered the wrong temperature variable:

[https://www.flightglobal.com/news/articles/temperature-
error...](https://www.flightglobal.com/news/articles/temperature-error-behind-
sunwing-737s-near-overrun-441346/)

------
sorenjan
Can we take a moment and reflect on the fact that all of this data is freely
available to anyone? I can sit in front of my computer, or anywhere with my
phone, and follow planes around the world with an accuracy of a few meters,
and replay the data at a later date.

The various flight trackers all use thousands of receivers around the world,
and most of them probably use the same kind of SDR chip that was originally
designed for USB TV and radio receivers.

[http://rtlsdr.org/#history_and_discovery_of_rtlsdr](http://rtlsdr.org/#history_and_discovery_of_rtlsdr)

------
smaili
If anything this is great free advertisement for Boeing's quality.

~~~
sjg007
As a pilot once told me: "If it ain't Boeing, I ain't going"

~~~
mprev
Brand loyalty is an amazingly powerful thing.

I wonder if anyone says, “I won’t be there Gus if it isn’t an Airbus”.

~~~
jackweirdy
Time’s a plenty in an a320

------
decasia
The obvious mystery is why you would keep flying for so long after an incident
like this...

~~~
burfog
A good reason would be fuel weight on possibly damaged landing gear.

Also, the airport wasn't good anymore. They had just destroyed the Instrument
Landing System at the end of the runway. Nobody should land there.

~~~
djsumdog
A lot of pilots don't use ILS and use a visual approach. That was one of the
issues with the SF airport, as the left runway was closed, the lights were off
and the pilot lined up with the taxi way.

~~~
deathanatos
> _the lights were off_

While it is true that the normal lighting was off (because it wasn't a valid
runway at the time), there was a lighted, flashing X to indicate that fact.
Along with the fact that the taxiway was not illuminated as a runway, _and_
the pilots were notified about the runway closure…

[https://ntsb.gov/investigations/Pages/DCA17IA148.aspx](https://ntsb.gov/investigations/Pages/DCA17IA148.aspx)

------
worldexplorer
I thought they track things like small vibrations in plane body due to such
incidents. How would they detect Bird
strike([https://en.m.wikipedia.org/wiki/Bird_strike](https://en.m.wikipedia.org/wiki/Bird_strike))
if hitting wall go unnoticed? Don't airports have sensors and cameras for such
situations to alert Air traffic control immediately?

------
irrational
It wasn't clear from the article. What kind of wall did they hit?

~~~
cycrutchfield
It's in the linked Twitter thread. It was a brick wall.

[https://twitter.com/shukla_tarun/status/1050581391828836352](https://twitter.com/shukla_tarun/status/1050581391828836352)

~~~
ams6110
Well a single layer, unreinforced brick wall isn't really that strong,
especially near the top edge. It's perhaps plausible they didn't feel anything
or at least nothing very alarming. I mean, the gear presumably still retracted
properly and deployed later for landing, so it wasn't damaged too badly.

~~~
djsumdog
Yea I'm interested in seeing what the passengers say. If they just heard a
bump or didn't suspect a thing, the plane may have just graised it and the
pilots didn't notice. If the passengers heard a noticeable sound or reported
concerns and were dismissed, that's grounds for negligence.

------
sn41
Honest question: why aren't pilots forced to take alcohol tests before
flights? There was some JetBlue incident about 10 years ago, IIRC.

~~~
toomuchtodo
Are forced alcohol tests given anywhere?

~~~
sn41
Not that I know of. Mandatory drug testing in sports is now common. When
operating heavy machinery, and when a lot of lives are at stake, I feel some
safety procedures are called for.

------
nitinreddy88
Its mystery how plane survived such a huge impact

Airport perimeter damage:
[https://mobile.twitter.com/ANI/status/1050582092688629760](https://mobile.twitter.com/ANI/status/1050582092688629760)

~~~
usrusr
The landing gear is built to withstand hitting a concrete runway with a 737,
whereas a thin brick wall can be brought down with just a hammer. It's like
rock-paper-scissors: wheels beat wall, ILS antenna beats fuselage skin.

------
jnsaff2
A similar incident that happened with a bigger plane that completed a 13h
flight:
[http://avherald.com/h?article=48c78b3a](http://avherald.com/h?article=48c78b3a)

------
YetAnotherNick
It looks like the plane couldn't properly take off(likely overloaded), and
it's not just an overrun. See the speed graph in the post, and the fact that
the gears were retracted that low.

~~~
FabHK
I don’t think we have enough information to make that statement yet. Could be
they forgot to set flaps, could be they miscalculated TO speeds, could be they
misconfigured auto throttle... As usual, need to wait for investigation and
report.

~~~
YetAnotherNick
Now we have that: [http://www.ptinews.com/news/10109087_Air-India-Express-
plane...](http://www.ptinews.com/news/10109087_Air-India-Express-plane-
possibly-overloaded--officials.html)

------
gandutraveler
Why is there a brick wall so close to runaway?

~~~
TheOtherHobbes
Because most pilots can fly professionally enough not to hit it.

~~~
lolc
There are failures modes a pilot has no chance of resolving.

~~~
jimktrains2
There are worse places to take off/land. Midway (MDW) has very little distance
from the runway to houses and highway. Princess Juliana International Airport
on Sint Maarten (SXM) has very little distance from the end of the runway to
the ocean. Gibraltar International Airport (GIB) is also basically on the
water.

Overrunning the runway is often considered avoidable from my limited
understanding. Planes are flight worthy under _a lot_ of issues. Even single
engine failure or engine fire after V1 (the speed at which you can't
abort/reject takeoff without overrunning the runway) isn't cause to
abort/reject takeoff.

With landing, the plane needs to touch down early enough and at the correct
speed to stay on the runway.

Overrunning the runway is never considered a "good" thing. Rejected takeoffs
that shouldn't have been and bad landings are often causes of death. They're
expected to not happen.

------
nirav72
Air India, an old antiquated government subsidized airline that should die.

~~~
SOLAR_FIELDS
The government has actually been trying to kill it for years but no one wants
it: [https://money.cnn.com/2018/05/31/investing/air-india-
privati...](https://money.cnn.com/2018/05/31/investing/air-india-
privatization-fails/index.html)

~~~
guiriduro
This might provide the government the opportunity to shutter it for good.

