
NTSB Issues Investigative Update on San Francisco Airport Near Miss - helper
https://www.ntsb.gov/news/press-releases/Pages/pr20170802.aspx
======
Animats
This was a very close call. Initial reports indicated it was like an ordinary
go-around. No. "The incident pilots advanced the thrust levers when the
airplane was about 85 feet above ground level. Flight data recorder data
indicate the airplane was over the taxiway at this time. About 2.5 seconds
after advancing the thrust levers, the minimum altitude recorded on the FDR
was 59 feet above ground level."

They overflew an Airbus A340 on the taxiway, tail height 55 feet.

~~~
johnm1019
Something doesn't add up then, the listed elevation for SFO is 13.1 ft MSL.
[http://www.airnav.com/airport/KSFO](http://www.airnav.com/airport/KSFO)

UPDATE: tolerances around GL are 20 ft [https://www.ecfr.gov/cgi-
bin/retrieveECFR?gp=&SID=&r=PART&n=...](https://www.ecfr.gov/cgi-
bin/retrieveECFR?gp=&SID=&r=PART&n=14y1.0.1.3.21#14:1.0.1.3.21.0.363.14.57)

~~~
DavidSJ
Also, they might not have been directly above the A340 at lowest altitude.

~~~
Animats
They were very close. See [1]. They were over the centerline of taxiway C, and
85 feet AGL crossing taxiway W. Minimum altitude was 2.5 secs later. There
were three planes ahead, an A-340, a B-787 (also 55 feet high at the tail),
and some UAL jet of about the same size.

A few feet lower and there would have been a collision.

[1]
[https://ntsb.gov/investigations/Pages/DCA17IA148.aspx](https://ntsb.gov/investigations/Pages/DCA17IA148.aspx)

------
planetjones
_Investigators could not hear what the Air Canada captain and co-pilot said to
each other during the aborted landing because their conversation was recorded
over when the plane made other flights, starting with a San Francisco-to-
Montreal trip the next morning. Recorders are required to capture only the
last two hours of a plane’s flying time_

I wonder what the procedure is in a near Miss like this. It looks like not
enough of the 'process' to capture evidence kicked in soon enough. Judging by
the photo and distances this looks like it was an imminent disaster, which
hadn't been clear to me previously.

Source: [https://www.theguardian.com/business/2017/aug/03/air-
canada-...](https://www.theguardian.com/business/2017/aug/03/air-canada-near-
miss-picture-shows-how-close-planes-came-to-crashing)

~~~
reustle
On top of that, storage is cheap. They can probably afford to keep
conversations longer than 24 hrs.

~~~
TrickyRick
Storage is cheap today, it wasn't 30 years ago when these rules were put in
place (And probably some of the systems manufactured)

~~~
justinjlynn
Retrofits to safety equipment are common when new issues are discovered. That
said, an enforcement action or a procedure change is probably necessary in
this case.

~~~
TrickyRick
For sure, and it might get changed now, but it wouldn't surprise me if planes
are still flying with age old cockpit voice recorders, simply because the
requirements on that front haven't changed. (Bearing in mind this is just an
educated guess, I have no idea about whether or not they have changed)

------
modeless
Before I couldn't imagine how anyone could make this mistake, but now I see
it. The pilots were familiar with SFO and knew that there were two runways,
but didn't realize the left hand runway lights were turned off, so they had an
off-by-one error when choosing the runway.

~~~
notatoad
i'm not a pilot and have no idea what it looks like when landing a plane at
night, so i really shouldn't be commenting here, but: the report says the one
operational runway had 2400 ft of approach lighting that was functional. The
disabled runway had no approach lighting, and presumably the taxiway didn't
have any approach lighting because nobody should be approaching a taxiway. So
yes, they were just "off by one", but they were off by one on a dataset of
one.

~~~
mosheroperandi
Yeah, but once you decide that the leftmost runway you see (with the dark void
on its left) is the left runway, then obviously the parallel strip of lights
to the right of it is the right runway. Sure, the lights look odd, and your
gut's giving off this feeling, but you see, that's the left runway, and I
don't see the right runway anywhere else, so this must be the...

They probably got stuck in several cycles of that before the contrary evidence
was overwhelming enough to break them out of their off-by-one mental model.

~~~
tajen
Can you see the X at the beginning of the runway while sitting in the pilot
seat? I was told the pilots' eyes are expected to be at mid-windshield height,
but pilots prefer their seats in slightly reclined position and no position is
compulsory.

~~~
dmurray
It's meant to be seen when approaching the disabled runway, not as a generic
landmark to help the pilots orient themselves. So it's not prominently visible
when approaching the taxiway.

------
Flammy
Previous discussion on this topic:
[https://news.ycombinator.com/item?id=14741605](https://news.ycombinator.com/item?id=14741605)

This literally could have been one of the worst accidents in American aviation
history had the pilots of the landing airplane failed to react in time. There
were 4 fully loaded and fueled passenger jets directly ahead of them.

~~~
phire
And they cut it extremely fine.

The final NTSB report will probably calculate this, but I'm guessing if they
had waited another second or two before shoving those throttles forwards they
would have hit a plane (or three).

Whats even more scary, is I get the impression that the pilots only shoved the
throttles forwards because the tower told them to abort.

~~~
TrickyRick
Does the NTSB do what-ifs? Seems odd for an investigative body to do guesswork
on what type of disasters could have occurred.

~~~
slavak
The NTSB does not do what-ifs in the sense of calculating expected body count
had an accident not been averted. They do, however, often investigate the
performance envelope involved in an incident/accident and the timeline for
possible corrective actions. So in an investigation it's quite common for the
NTSB to look into how initiating corrective action at different points in time
would have affected the outcome. e.g.: Sentences like "the pilots could have
[taken corrective action X] until Y seconds before collision is a pretty
standard sentence to see in an investigation report.

This kind of information is important for determining the available safety
margin and the proper changes to recommend in order to prevent similar
incidents in the future.

~~~
TrickyRick
Yeah, that kind of conclusion makes more sense as opposed to "If the events
wouldn't have played out as they did, X would have happened". No one really
cares, except to know that it would have been bad, which is why there is an
investigation to begin with.

------
zkms
So the guy keying up and saying "Where is this guy going?" and "He's on the
taxiway" might actually have made a difference in the outcome, huh:

> The flight crew of the first airplane in queue on taxiway C (UAL1)
> transmitted statements regarding ACA759, one of which mentioned the
> alignment of ACA759 with the taxiway while ACA759 was on short final (see
> figures 2 and 3).

> The flight crew of the second airplane in queue on taxiway C switched on
> their airplane’s landing lights as the incident airplane approached.

~~~
mannykannot
It may be doubly fortunate that that multiple pilots and controllers did not
attempt to say this at the same time. At Tenerife, both the Pan-Am crew and
the tower suspected that the KLM aircraft had started its take-off roll, and
both tried to warn its crew at the same time, but the resulting radio
interference between the concurrent transmissions made the messages
unintelligible.

This was discussed in detail here:

[http://www.salon.com/2002/03/28/heterodyne/](http://www.salon.com/2002/03/28/heterodyne/)

The author states that there is a feasible technical solution that, at the
time of the article (2002) had not been mandated. Does anyone know if the
situation has changed?

------
phkahler
I'm think I'm getting it now. Look here at the map:

[https://www.google.com/maps/@37.6265932,-122.3812022,15z?hl=...](https://www.google.com/maps/@37.6265932,-122.3812022,15z?hl=en)

28L is longer than 28R. Similar to how 28R (or at least its lighting) is
longer than taxiway C. The general geometric appearance of the lighting was
probably similar enough to what they were used to that it looked mostly
correct. As for the X, it was 20 feet wide and about 1000 feet away from where
they were aiming, so it would not be relevant to the incident.

~~~
Doxin
Maybe I'm looking at this wrong, but 28L is most definitely shorter than 28R.
Unless they marked the runways wrong of course but somehow I doubt that.

~~~
phkahler
>> Maybe I'm looking at this wrong, but 28L is most definitely shorter than
28R.

You are looking at it wrong. 280 degrees from north would be approaching from
the upper right heading down and to the left on the map. From the pilot point
of view 28L would be to the east and extends further out into the bay.

~~~
phkahler
Well that's just a big oops on my part. It's 19L and 19R I was looking at, not
28L & R

------
probablybanned
VASAviation made a video on this with radio traffic from the incident.

[https://www.youtube.com/watch?v=ZW-
ETmZU0u8](https://www.youtube.com/watch?v=ZW-ETmZU0u8) (1:33)

~~~
TrickyRick
That video doesn't match the sequence of events in the report (Which makes
sense, it was published a few weeks ago). According to the report the remarks
from UAL1 come as the airplane is overflying the taxiway.

------
viraptor
I've seen people mentioning this could be a big disaster, but I'm curious
exactly what the effects could be. Specifically, ignoring the wheels for the
moment, would the hull of the landing plane slide off on contact at all, or
would the planes just get squashed? I have no intuition about friction /
stiffness of materials at that scale. (I'm also assuming the planes were at
least a little bit offset to the side)

With the wheels down, they would just tear through the hull of the lower
plane, right?

~~~
abritinthebay
It wouldn’t have been just the wheels.

They’d have flattened onto each other in a big squash that blew fuel
everywhere.

It would have probably continued due to momentum as a fireball towards the 3
other fully loaded planes.

Basically it could have been a 5 fully loaded plane bowling alley of flaming
metal at 150mph

~~~
dakrisht
This. Sure. But pure speculation. The forward momentum of that airplane could
have clipped a tail and taken it off while pulling up and max thrust. He was
wayyyy below minimum decision height (called out and set before landing,
usually a few hundred feet).

OTOH, he could have very well collided with the other Airbus on the taxiway
rapidly halting his forward momentum and exploding into a fireball
subsequently taking out everything for half a mile ahead.

What's alarming her is the distance of the Air Canada jet to the ground, less
the tail of the Airbus = this guy was FEET AWAY from clipping that jet.

------
bgentry
I would love to see the video that frame is taken from to watch the arc of the
plane as it initiated go-around and missed a collision by just a few feet.

~~~
mosheroperandi
From the current report
([https://ntsb.gov/investigations/Pages/DCA17IA148.aspx](https://ntsb.gov/investigations/Pages/DCA17IA148.aspx)):

 _The NTSB has obtained a security camera video from SFO of the incident
approach that will be released along with the other factual information when
the public docket for this incident is opened in the next several months._

------
greenhouse_gas
What I don't understand (and I'm being honest here) is that between GPSs,
computers, and HUDs, how do these errors still happen?

I mean that if your GPS sees you're aiming at the wrong runway, why can't it
alert the pilot (and/or tower) that it's going to miss.

~~~
matt_wulfeck
I'm wondering the same thing. Why don't planes land themselves at this point?

~~~
kpil
The main reason is that computers aren't very smart although I know that even
some developers think that.

Actually they can autoland but not everywhere and then you still need to tell
them where, basically tune them in on the right glide path. Then you really
need to be prepared to take over any second, which is a dangerous position on
its own. (Just like all self driving cars right now.)

It's still possible to select the wrong ILS beacon or entering the wrong speed
or whatever, and something can still show up in front of the plane.

It's just better in low visibility where you otherwise manually have to follow
the ILS 'needles'.

Didn't a plane crash there killing some chinese schoolgirls just because the
pilots forgot to set the correct speed. Either it was set too low or they set
it but did not activate it. And then the monitoring pilot forgot to monitor
the speed since the autopilot never fails...

~~~
ohwaitnvm
Asiana 214 -
[https://en.m.wikipedia.org/wiki/Asiana_Airlines_Flight_214](https://en.m.wikipedia.org/wiki/Asiana_Airlines_Flight_214)

"Over-reliance on automation and lack of systems understanding by the pilots
were cited as major factors contributing to the accident."

~~~
ziedaniel1
The very same airport, in fact.

They accidentally turned off auto-throttle and took far too long to react to
the falling airspeed.

------
TrickyRick
The map view seems a bit off to me, UAL1 obviously saw the incoming plane and
on the photos it looks to me like there are 4 planes in a straight line, yet
UAL1 is oriented in the other direction on the radar.

~~~
mosheroperandi
I think it's the case as depicted in the first radar image, UAL1 turned 90-ish
of degrees right on the exit from the taxi-way, and the other three lined up.
It could be the angle of the camera is such that it's an illusion they're all
in a straight line. That probably still gives them plenty enough view out the
side of cockpit to see that the plane they're expecting is heading behind them
and not in front of them where it should be.

I think the orientations in the subsequent screens where UAL-1 looks turned
around are probably a case of the radar over-extrapolating from its heading
from the turn and then not being able to tell its heading while it's parked.

------
LittlePeter
How about using different colour lights for taxiways and runways. They are
already using different colour tarmac lines: yellow vs white.

~~~
alexeckermann
> Lights for taxiway C were also on and set to default settings that included
> centerline lights (green) along its length. Default settings also included
> edge lights (blue) and centerline lights (green) illuminating the transition
> or stub taxiways from the runway to the taxiway.

> Runway and approach lighting for runway 28R were on and set to default
> settings, which included a 2,400-foot approach lighting system, a precision
> approach path indicator, touchdown zone lights (white), runway centerline
> lights (white at the approach end), runway threshold lights (green), and
> runway edge lights (white at the approach end).

Taxiway: centre green along length, blue edge lights. Can have planes on it.
Runway: centre white along length and edges (also landing zone), perpendicular
green at end thresholds. Should not have planes on it.

~~~
brianshaler
The planes on the taxiway have white takeoff/landing lights. It sounds like
the second in the queue didn't turn theirs on until just before the incident,
but if any of the others had theirs on prior, it could contribute to
misidentifying the taxiway. I think it's common to have the lights on while
taxiing and turning them off at rest.

------
throw2016
Wouldn't this whole problem disappear if runways were designed differently, at
the minimum one exclusive for landing and one for takeoff with no chance for
planes landing and planes taking off to meet, like 2 parallel hockey sticks.

Both runways would be painted and lit up completely differently with large
lettering explicitly saying take off and landing.

~~~
krallja
No. The captain was not attempting to land on a runway. He was attempting to
land on a taxiway, which is painted and lit up completely differently, and
also covered in airplanes.

------
rcthompson
Maybe taxiways parallel to runways shouldn't be a thing.

~~~
URSpider94
How do you propose to get to and from the runways?

~~~
rurounijones
I may be putting words in OPs mouth here but I imagine he meant not putting
parallel taxiways so close to the main runway.

I know that space restrictions make this very tenuous but I must admit that
looking at the overhead on
[https://ntsb.gov/investigations/Pages/DCA17IA148.aspx](https://ntsb.gov/investigations/Pages/DCA17IA148.aspx)
that the taxiway marked C looks a lot more like a runway than the one marked
F. (due to the width maybe?)

