Pilot explains how Air Canada jet nearly caused an aviation disaster



NTSB released footage of
Air Canada Flight 759.

NTSB

  • Air Canada Flight 759 attempted to land on a taxiway at
    SFO.
  • The incident could have been a major aviation
    disaster. 
  • Smith explains how the Air Canada pilots could
    have made such a mistake.


Editor’s note: Patrick Smith is a commercial airline
pilot who currently flies Boeing 757 and 767 aircraft. Smith also
runs the blog AskThePilot.com
and is the author of the book “Cockpit
Confidential.” 

On July 7th, an Air Canada jet nearly landed on a busy
taxiway at San Francisco International Airport, apparently
mistaking the taxiway for runway 28R. Taxiway C, as it’s
designated (“Charlie,” pilots would call it, using the phonetic
alphabet), runs parallel to the runway on its north side.

At least four other planes were on the taxiway at the time.
At the last minute, the pilots of flight AC759, an Airbus A320
with 140 people aboard, broke off the approach and climbed
away.

This could easily have been disastrous —
something akin to the USAir crash in Los Angeles in 1991. Luckily
the Air Canada crew, aided in part by startled pilots on the
taxiway, realized in time that they were lined up
incorrectly.

What happened in 1991 was an air traffic controller’s
deadly mistake. What happened the other night in SFO appears to
be straightforward crew error, the million-dollar question being
how the pilots got into this situation in the first place. Runway
28R is equipped with the standard electronic landing aid (ILS)
and fancy approach lighting found on most major runways. The
aiming point should have been pretty obvious.

Air Canada Airbus A320 C-FKCKThe Air Canada
Airbus A320 that operated Flight 759.
Flickr/Lord
of the Wings

That said, San Francisco has its quirks. Only about three-hundred
feet separate runway 28R from taxiway C, and approaches into SFO
are often busy and very high-workload. Also, non-precision
approaches to this runway are common, and sometimes the ILS isn’t
used. I land on runway 28R all the time, and the most common
approach is something called an “RNAV visual,” a hybrid procedure
in which the final segment is flown visually, with no
runway-specific guidance from the instruments. You can transition
to the ILS in those final seconds, but this isn’t always done.
And, it was midnight. Maybe fatigue played a role.

Another factor is that the parallel runway, 28L, was closed
that evening, with its approach lights turned off. Pilots landing
at SFO normally expect to see a pair of runways, laid more or
less next to one another. Perhaps they mistook 28R for 28L, which
would have been dark, and saw taxiway C as 28R.

I landed on runway 28R two nights ago, right about at dusk.
Runway lighting and taxiway lighting are very different, and
this, among other things, should have been a huge clue For Air
Canada. They 
should never have broken off
the approach a lot sooner. But as we descended toward the
threshold, I couldn’t help thinking: taxiway C does indeed
resemble a runway!

Those aren’t excuses, but under the right set of
circumstances, what happened isn’t totally beyond the pale. And
there had to be some external contributing factors aside from
pure recklessness on the part of the pilots.

SFO_at_night San Francisco International AirportSan Francisco
International Airport at night.
Wikimedia Commons

How close a call was it? That would
mostly 
depend on how far out the A320 was —
distance from the 
threshold and altitude — when
the crew began the go-around maneuver. Early on, reports said the
plane never got lower than 350 feet above the ground. That’s the
height of a 30-story building and would represent fairly adequate
clearance. The voices on the recordings, meanwhile, show concern,
as well they should, but remained measured and calm, suggesting a
catastrophe was never imminent. However, investigators are now
saying the Air Canada crew flew a full quarter of a mile along
the taxiway before beginning a 
climb, and
came within 55 feet of a taxiing United jet’s tail. If so, that’s
downright alarming, and about as close a call as you can have.
How and why the crew got to that point, and why air traffic
control didn’t notice their mistake and alert them sooner, is
unclear.

Also unclear is why air traffic control didn’t notice the
pilots’ mistake and alert them sooner. In the controllers’
defense, however, the taxiway and the runway are close together,
and they would’ve been watching from a considerable angle,
throwing off the perspective. I’m not sure their radar would have
shown anything too worrying either, at least until the final
seconds. Planes sometimes zig and zag a bit on final approach.
And, after a clearing a crew to land, you more or less take it
for granted they will know the difference between a runway and a
taxiway.

Air Canada Flight 759 ntsbNTSB

As they approached the airport, the pilots queried air traffic
control about traffic on the runway. They saw something that
concerned them. The tower’s reply, that the runway was clear, may
have given them a false sense of security and encouraged them to
continue. They should not have gotten as close as they did, but
it can be very difficult to see other aircraft on the ground at
night, even when those aircraft have all of their
appropriate lighting on. Just ask the USAir
crew 
than landed on top of that plane at
LAX.

Runway numbers correspond to the strip’s magnetic
orientation. Just add a zero. Runway 28 is aligned 280 degrees —
just a smidgen north of due west. The opposite end would be
runway 10, pointing 100 degrees. Runways laid in parallel also
carry a left or right — “L” or “R” — suffix. SFO’s runway 28L was
the one on which an Asiana Airlines 777 crash-landed on July 6,
2013 — four years before Air Canada, almost to the day.

Read the original article on AskThePilot.com. Copyright 2017. Follow AskThePilot.com on Twitter.

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