
Abstract of the NTSB Report on Air Canada flight 759's taxiway overflight at SFO [pdf] - CaliforniaKarl
https://ntsb.gov/news/events/Documents/DCA17IA148-Abstract.pdf
======
nutcracker46
The report identifies good preventive measures. Autotuning the ILS would be
handy, as would an aural alert for lateral deviation, perhaps announcing,
"Localizer, Localizer."

The crew may have caught the closure of 28L and planned better with a review
of NOTAMS before top of descent and including them in the approach briefing.

When I'm up there, and sleepy, I ask for a coffee and pull out the NOTAMS for
one last look before we pull up the approach in the computer, manually set up
the radios, and do the briefing.

On final approach, more precise ground based monitoring would be nice to have
in case things are fubar in the plane.

~~~
augustz
Just for SFO you have 84 NOTAMs.

!SFO 06/079 SFO OBST RIG (ASN 2017-AWP-3368-NRA) 373740N1222224W (0.5NM NE
SFO) 41FT (34FT AGL) FLAGGED AND LGTD 1806201400-1811010100

This is a flagged and lighted obstruction half a mile way that is 34 feet
above ground level.

Now put in a full route and takeoff airport and maybe if you have had some
stops during the day. The NOTAM seems a bit long. Then if are overseas and
have to deal with the BS political notams. Check out greece and turkey notams.

...THE REF (B) TURKISH NOTAM A3009/16 LTAAYNYX (111139 EUECYIYN JUL 2016) HAS
NO GROUND, CANNOT PRODUCE ANY INTERNATIONALLY LEGAL EFFECT WITHIN ATHINAI FIR/
HELLAS UIR AND IS CONSIDERED NULL AND VOID.

I'm curious how many pilots fully read all NOTAMs, locate them geographically
to understand where they are etc etc on every flight.

~~~
powercf
Outputting that in lower case could be a small step to making them easier to
parse, and therefore more likely to be read. I find the text you posted tiring
even to look at.

THE REF (B) TURKISH NOTAM A3009/16 LTAAYNYX (111139 EUECYIYN JUL 2016) HAS NO
GROUND, CANNOT PRODUCE ANY INTERNATIONALLY LEGAL EFFECT WITHIN ATHINAI FIR/
HELLAS UIR AND IS CONSIDERED NULL AND VOID.

vs

The ref (B) Turkish NOTAM A3009/16 LTAAYNYX (111139 Euecyiyn Jul 2016) has no
ground, cannot produce any internationally legal effect within Athinai
FIR/Hellas UIR and is considered null and void.

~~~
DocTomoe
Yeah, good luck with changing hundreds of established, life-or-death-systems,
most of them actually embedded in planes in the airline industry worldwide, at
the same cutover date, to suddenly support mixed-case script.

Have a one-hour watch to understand what kind of beast you are wrestling here:
[https://media.ccc.de/v/31c3_-_6308_-_en_-
_saal_1_-_201412281...](https://media.ccc.de/v/31c3_-_6308_-_en_-
_saal_1_-_201412281245_-_beyond_pnr_exploring_airline_systems_-_saper)

~~~
michaelt

      good luck with changing hundreds of established, 
      life-or-death-systems, most of them actually
      embedded in planes
    

Seems to me that's precisely the sort of thing the NTSB _is_ supposed to be
able to do?

Of course IMHO a mere change of case doesn't go far enough.

~~~
DocTomoe
You do realize that US planes still have to be able to fly to countries other
than the US, and vice versa, right?

------
organman91
As a private pilot, small planes going down occasionally are just a fact of
life. But this incident scares me. There were four planes lined up on the
taxiway the Air Canada narrowly missed. The worst aviation accident ever was a
collision of two 747s resulting in 583 deaths:
[https://en.wikipedia.org/wiki/Tenerife_airport_disaster](https://en.wikipedia.org/wiki/Tenerife_airport_disaster)
\- this could have doubled that number.

~~~
oh_sigh
Is it plausible that that AC759 could have taken out all 4 other planes? I
don't really have a sense of the distances planes are spaced out on taxiways
at major airports.

~~~
DocTomoe
Spacing between planes on a taxiway is a lot shorter than you would imagine.
Depending on type, a 25-50 meters apart is common.

Keep in mind that these four planes were preparing for take-off, meaning that
they were fully fuelled...

------
abaillargeon
I've been anticipating the release of this report this since I heard about the
incident.

I work on an avionics product that's designed to prevent this exact scenario.
We use the aircraft's position along with a database of runways and taxiways
to determine if the aircraft is approaching the runway the pilot intends. If
we determine the aircraft is landing, we issue a visual and aural alert to the
pilot ("TAXIWAY LANDING" or "NOT A RUNWAY").

~~~
sandworm101
How do you account for winds and pressure differences, both of which will
modify an approach. A plane may look like it is landing short, or to the
left/right, when in fact the pilot is anticipating a change in wind as they
drop in altitude.

~~~
abaillargeon
Good question. We've run into similar issues while developing a related
feature that helps pilots perform a stable approach. Sometimes pilots were
performing a circling approach to a different runway, and a naive approach to
determining lateral deviations would have caused a nuisance alert.

For this particular system, the alerting threshold is only met when we've
determined that the aircraft is "landing". As I mentioned in another comment,
I'm vague about this point because it depends on the way the aircraft
manufacturer has configured this state machine. Sometimes we use throttle
position, altitude, speed above Vref, gear position, height above threshold,
etc. You're correct that conditions can slightly modify an approach, but we're
confident that we can nail down "we're landing" closely enough to mostly
eliminate nuisance alerts.

~~~
oh_sigh
What's your market? Light aircraft? airliners?

~~~
abaillargeon
Our market right now is general aviation and business jets. I believe our
biggest customer is the Cessna Citation Longitude (max takeoff ~40,000lbs). I
noticed the NTSB abstract had some recommendations for inclusion and
certification of a system on a broader range of aircraft. Larger aircraft are
required to have similar safety-related systems such as terrain, reactive
windshear, etc so this could be the next step.

------
mmaunder
This is what is called a 'cascade of failures' in aviation - and the term is
used elsewhere. Multiple failures resulting in a catastrophic failure. In your
own life and goings about, it's sometimes interesting to do a failure analysis
and you'll often find you experienced a cascade.

It's really unfortunate that the cockpit voice recorder was overwritten. I'm
guessing they're using very old technology where storage space is at a
premium.

They're still using the flashing X on closed runways - e.g. at SEATAC right
now. The lights looked incandescent a couple nights ago while passing the X.
So not very bright or visible.

This accident would probably have been one of the worst in history. Multiple
passenger planes on the taxiway taken out by a passenger jet.

------
SaberTail
If anyone would like to listen to the ATC radio:
[https://www.youtube.com/watch?v=ZW-
ETmZU0u8](https://www.youtube.com/watch?v=ZW-ETmZU0u8)

~~~
joncrane
OMG that is just pure gold! The United guy is SOOOO laconic. Like him speaking
up on the open freq saved hundreds of lives and he sounds like he's reading
yesterday's corn future prices.

~~~
stordoff
Reminds me of the BA Flight 9 announcement:

> Ladies and gentlemen, this is your captain speaking. We have a small
> problem. All four engines have stopped. We are doing our damnedest to get
> them going again. I trust you are not in too much distress.

------
aeternus
I'm surprised that remote video cameras aren't used by tower controllers.

The perspective of the control tower makes it difficult to catch issues like
this, but a simple video camera aligned with the center-line of each runway
would allow controllers to more easily verify that planes are lined up as well
as other possible issues like gear down & locked, etc.

~~~
zkms
> I'm surprised that remote video cameras aren't used by tower controllers.

I'm surprised that forward-looking infrared cameras aren't more commonly used
in civilian aircraft, especially given the availability of staring arrays with
decent resolution/framerate that don't require cooling.

Even without the requisite certification for use as a for-realsies landing
aid, it's nevertheless a useful tool to get situational awareness in inclement
weather / at night.

~~~
outworlder
They are more commonly found aboard 'experimental' aircraft because of the
certification issues you pointed out.

~~~
DuskStar
And high-performance infrared cameras are also probably one of those things
that end up on arms control lists. (Since it's not just useful for spotting
planes on your "runway", but also for spotting tanks or people on your hill
requesting an ordnance delivery)

~~~
bigiain
I have several of these emails (when ordering to Australia):

Hello,

Your recent SparkFun order contains 1x KIT-13233: FLiR Dev Kit. This item is
export controlled by the United States government. By law, we are required to
gather the following information from you as the importer:

1) Do you intend to sell or send this item to anyone in any of the following
countries: Cuba, Iran, North Korea, Sudan, or Syria?

2) Will this be used in any military applications?

3) Will you be the ultimate end user of this item? If no, please go to 3.a.

3.a) If you are not the end user, who will this item be sold or transferred
to? Please include full name, physical address, end use and confirmation that
they will not sell or transfer this item to any party in Cuba, Iran, North
Korea, Sudan or Syria.

4) What is the end use of this item?

5) Where is the location where the item will be used?

Response to all five questions is necessary before we are able to ship your
order. If we don’t hear back from you within one week, your order will need to
be canceled.Please let me know if you have any questions. I hope you have a
great day!

~~~
semi-extrinsic
I've had this exact one for all sorts of kit. Digital pressure regulators,
optics alignment hardware, etc.

------
cmurf
I'm not operationally familiar with SFO. But based on experience at other
airports, a taxiway at night can be a sea of black at even 100' above the
ground. I would probably see airplane navigation lights at some point, but
would I bet my life on it? No. So this incident has to be taken seriously.

However, I'm still not clear from this reporting how the crew mistook blue
taxiway lighting for white runway lighting. This isn't supposed to be subtle,
and I haven't ever experienced it to be subtle.

Edit: OK there is a partial explanation here that appears as though at the
time they committed to taxiway C as runway 28R, the visual cue they relied on
was airplane lighting looking like it was runway lighting. Airplane taxi and
takeoff/landing lights are white, navigational lights are green or red.
Strobes usually aren't on while on the ground or at least probably shouldn't
be.

It's an interesting dilemma. And fatigue is a significant contributing factor
as well.

~~~
oasisbob
I don't understand it either.

Here in Seattle, SeaTac airport has a parallel taxiway (Taxiway Tango) with a
long history of being mistaken for a runway. The list of things tried so far
to resolve the issue is interesting:

[https://www.bizjournals.com/seattle/news/2015/12/31/tango-
ta...](https://www.bizjournals.com/seattle/news/2015/12/31/tango-taxiway-a-
history-of-mistaken-landings-and.html)

~~~
wmblaettler
The very first thing I thought of upon reading your comment "The list of
things tried so far to resolve the issue..." was "What about a big lighted
'x'?" then I clicked the link.

~~~
jonah
I'd like to know why they removed it.

~~~
PhantomGremlin
Exactly my question. It's 9000+ feet long. Put a lighted red X on it every
1000 feet. Or, maybe Xes aren't the answer, but there must be _some_ technique
to produce a startling visual warning.

It's probably a situation like Chesterton's fence. There are probably good
reasons for not having the Xes. At least I hope so, I hope it's not just "that
costs money and then we have to maintain it". The money can't be an issue. How
much would 500 or 1000 deaths cost? How expensive are all the other proposals
which have been mentioned? Those aren't cheap either.

------
debt
"The cues available to the flight crew to indicate that the airplane was
aligned with a taxiway did not overcome the crew’s belief, as a result of
expectation bias, that the taxiway was the intended landing runway."

Damn. It didn't matter that the whole world was telling him it was a taxiway
because he was so sure it was a runway.

------
bahmboo
Gotta hand it to the NTSB - they are thorough. This is just the abstract.

~~~
glup
Also that they cite fatigue / circadian low as one of the core causes. I
thought they might avoid it because of the potential cost implications for the
airline industry.

~~~
scrumper
Worth noting that the Canadian regulations are looser than USA in that respect
- the Air Canada pilots were in compliance with home regs, but would have been
in breach of FAA regs.

Other point is that the NTSB isn't generally particularly shy about calling
out the need for expensive changes (one example being their recommendation for
fuel tank inerting systems after TWA 800). They have no power to mandate their
recommendations be implemented after all: that's the job of the FAA.

~~~
jackpirate
Why does a plane in US airspace not follow FAA regs?

~~~
scrumper
Well, it does pretty much, just not that bit (14 CFR 117). In this Air Canada
case it's governed by 14 CFR part 129, which covers operations by foreign air
carriers in the USA.

[https://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol3/xml/CFR-...](https://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol3/xml/CFR-2011-title14-vol3-part129.xml#seqnum129.15)

EDIT - removed erroneous reference to 14 CFR 121.480-> which applies to cargo
ops.

------
tetrep
> Cockpit voice recorder (CVR) information was not available for this incident
> because the data were overwritten before senior Air Canada officials became
> aware of the severity of this incident.

How long are recordings normally kept? I would assume at least a few days for
mundane flights (storage is cheap, isn't it?) but any sort of incident similar
to this I would assume they keep recordings for much longer, if only for
internal purposes.

~~~
Havoc
The tower recordings are posted above.

>(storage is cheap, isn't it?)

Not on ancient planes where everything needs a billion certifications from all
sorts of regulatory bodies.

~~~
avar
There's other issues at play. Pilots hate the idea of more monitoring of the
cockpit, and have been vocal in trying to prevent e.g. a video recording of
the cockpit being part of the "black box", even though it would have helped to
shed light on a lot of aviation incidents[1].

1\. [https://www.wired.com/2014/07/malaysia-370-cockpit-
camera/](https://www.wired.com/2014/07/malaysia-370-cockpit-camera/)

------
Waterluvian
Speaking with a fair level of ignorance, how hard would it be for some onboard
computer to be freaking out that a landing attempt is being made way off
course of a known runway?

Going to guess this is one of those things where, yes, we have all the
requisite technology, but practical implementation is the hard part.

~~~
abaillargeon
I get excited seeing stories about aviation on HN because it's something I
work on every day. I've written a few comments above but I'm developer on the
system you described (and more) being used in aircraft today.

With a GPS and onboard databases of runways and taxiways, we can determine if
a pilot is attempting to take off or land on a taxiway. The key is preventing
nuisance alerts when the pilot is just flying around and happens to be aligned
with a runway. The "11 secret herbs and spices" depend on the aircraft but are
usually speed and configuration (ie landing gear) based. Approaches are fairly
predictable and we can use that to sequence through a state machine that tells
us the pilot intends to land.

Here's a video of the system on a G1000 (meant for smaller planes) skip to
0:45ish
[https://www.youtube.com/watch?v=V2bswm0w4cY](https://www.youtube.com/watch?v=V2bswm0w4cY)

~~~
Waterluvian
Thank you for sharing. Really cool to see just how much real-time GIS there is
in aviation these days.

------
CaliforniaKarl
As per [https://www.ntsb.gov/news/press-
releases/Pages/NR20180925b.a...](https://www.ntsb.gov/news/press-
releases/Pages/NR20180925b.aspx):

>The full report will be available on the NTSB website in several weeks.

------
oh_sigh
Are there any reports from passengers on the taxiway planes? I'd have to
imagine an A320 flying 60' over your roof would cause a fairly large
disturbance.

------
gok
It's kind of baffling to me that there's a system for detecting collisions
with other airplanes in the sky (TCAS) and a system for detecting collisions
with the ground (EGPWS) but not system for detecting collisions with other
airplanes on the ground. This easily could have killed a thousand people.

~~~
hangonhn
Different problems, no? Trying to pick out an airplane against the ground is
different from detecting an object in the air, which doesn't generally reflect
radio back, and detecting the ground, which does reflect. The problem you're
describing requires you to differentiate between two things that both reflect
signals back to you. It's obviously do-able since the military does it all the
time for targeting. However, I doubt it's cheap and there might be cheaper
ways to do it that don't leverage the two systems you've mentioned.

~~~
eesmith
TCAS uses active transponders, not radar reflection.
[https://en.wikipedia.org/wiki/Traffic_collision_avoidance_sy...](https://en.wikipedia.org/wiki/Traffic_collision_avoidance_system#System_description)

------
tialaramex
CVR overwrite is bad news here. The crew knew this was a serious problem when
it happened, there's no way they should have allowed the CVR, crucial evidence
of exactly what happened, to be overwritten.

Perhaps the full report will have more detail on this, as it stands I have to
believe somebody made the decision to overwrite this because they thought it'd
be better if it didn't exist. Whether that's the crew, their bosses or other
staff, somebody managed to go from "serious incident, preserve evidence" to
"maximum ass covering" and that person or persons are an obstacle to effective
investigation and thus to safe air travel.

~~~
cpitVoxRec
They actually do clearly state in this PDF that a degree of fault lies in the
crew being compromised by fatigue. Operating for 19 hours straight definitely
places an individual in an area where one can be fighting to pay strict
attention, even when it really counts.

There's also plenty of communication with Air Traffic Control in the tower,
and not a whole lot of gaps to introduce significant mystery, so it's pretty
unlikely that there would be anything earth shattering on the cockpit voice
recorder.

~~~
tialaramex
What I'd expect the CVR to provide good evidence of is the extent to which
crew were actually doing the checks that should have caught this error, and
their reaction when they belatedly discovered their true position.

Without even trying to mislead investigators a human will report a sanitised
version of events when not cued by facts. "Then I scratched my arse and
sniffed my finger" is not going to appear in this sanitised version of events
even if true. Neither is "I glanced at the panel, I know I'm supposed to scan
it, but usually anything important flashes red". The tower log helps, CVR is
better, and CCTV better again.

It also really helps to get into the routine of analysing this stuff. If your
aircrew routinely skip steps 4, 18 and 23 from the checklist, only finding
that out when 200 passengers die in a crash is stupid. Let's find out now.
That needs lots of heavy lifting, pilots have to trust the airlines not to
fire them for ordinary human frailties, and airlines have to accept that their
pilots are human and "But the manual says not to do that" doesn't make it stop
happening magically.

You're right that fatigue is an obvious element here, and there are several
technical countermeasures mentioned. I definitely don't want to come across as
believing in a conspiracy to hide the facts, but on the other hand I struggle
to believe that it took over 30 minutes to get this thing back down after the
incident and so the overwrite was not a decision. And if we agree it was a
decision, it was a seriously bad one that should not be repeated.

~~~
cpitVoxRec

      I struggle to believe that it took 
      over 30 minutes to get this thing 
      back down after the incident
    

If your inferring that a 30 minute offset was introduced, in order to dump the
stale audio buffer, before permitting access to the CVR instrument on the
ground, I'd offer the idea that there were 4 other planes on the taxiway,
waiting to take off, and that the intervening 30 minutes could be eaten up by
letting those planes depart, based on an array of other factors.

A concerted effort to dump the recorder buffer would require the participation
of more than just the flight crew, since it manipulates the standing traffic
pattern. Not an impossibility, and we know that in-group "walls of silence"
definitely accumulate in high-intensity industries, but the air traffic
control audio suggests a really minor transgression of situational awareness,
even if the circumstances are assuredly unforgiving ones.

In the radio audio, the pilot clearly states that he's noticing lights on what
he imagines to be his runway, and asks for confirmation as to what they might
be. The tower reaffirms that he's all clear. Only then does a pilot from one
of the planes on the ground speak up, and complain.

At that moment, both ATC and the plane realize the error. It's arguable that
the pilot anticipated a likely go-around, based on intuition that the lights
he was observing were definitely other planes, and that what appears to be an
extremely close call proves it's own margin of error as reasonable, given that
the participants recovered from the error.

~~~
tialaramex
No, I'm _implying_ that I don't believe it took 30 minutes to get down. Based
on the abstract I would say you're going to find out it came back down in
under 30 minutes, and then "oops" they let the CVR be re-used, overwriting the
recording anyway.

The text from the linked abstract says: "Cockpit voice recorder (CVR)
information was not available for this incident because the data were
overwritten before senior Air Canada officials became aware of the severity of
this incident"

One of the nice things about working in the Web PKI is that this crap doesn't
get you anywhere since keeping records is one of the requirements, and any
time the options are "This issuer might be crooked or they might be
incompetent" both are disqualifiying anyway, no need to figure out which it is
to make a determination.

It lets me sleep easier, were people at Symantec reckless, or were they so
greedy that they actively tolerated fraud? Don't care, not my problem now, let
their shareholders worry about it.

~~~
cpitVoxRec
Oh, I don't know about these particular ideas you're chasing. There are quite
a number of independent, redundant resources that would be very difficult to
align forgeries across and present as fraudulent data, worldwide, for weeks,
months, and even years after the incident.

It just sounds like a fishing expedition for some kind of cover up that
exploits an incredibly narrow gap, covered by a myriad of alternative
information sources that are more than capable of sealing up an air tight
sequence of events by other means.

Open, consumer information sources like flightaware.com alone had the answer
to the questions you're asking, long ago.

The radar history for this event was paywalled here for days after the event:

[https://flightaware.com/live/flight/ACA759/history](https://flightaware.com/live/flight/ACA759/history)

The open, freebie log only gives like two weeks of charts, but the data you
mention was lying around, available for like 8 months, to anyone with premium
access to that particular service. And anyway, I'm sure it's just a
convenience wrapper to public data that's still floating around to anyone
willing to dig.

Here's another service, if you've got $500 bucks, and _really_ would like to
know right now:

[https://www.flightradar24.com/data/flights/ac759/](https://www.flightradar24.com/data/flights/ac759/)

And to reiterate, this is only costing money today on account of being late to
the party.

Multiple systems surfaced this data to the world in real time, and openly
back-logged for months after. I'd bet good money a wide audience fact checked
exactly what you've suggested a long time ago (even here:
[https://news.ycombinator.com/item?id=14741605](https://news.ycombinator.com/item?id=14741605)).
But my opinion isn't very important when the information is available in a
general sense, to anyone who really wants it, even now, more than a year
later. Feel free to be suspicious about these resources being far downstream
and non-official consumer products, but if that doesn't suffice, then other
(much, much bigger) doubts occlude any potentially satisfactory assessment
which won't get solved in a random thread by amateur internet detectives like
us.

