NTSB releases initial details on AC759 SFO incident


Details from the FAA on the AC759 incident, including positional data and time stamps.
Details from the FAA on the AC759 incident, including positional data and time stamps.

The Air Canada A320 that almost landed on a crowded taxiway at San Francisco International Airport on 7 July 2017 was only 59 feet above the ground at its lowest point and that occurred between two of the four aircraft on the taxiway. This is one of the details the FAA NTSB released today as part of its initial investigation into the Air Canada flight 759 incident. The Air Canada A320 passed over a United 787 and Philippines Air A340 while still descending; it then passed over another United 787 and a United 737 as it climbed, after instructed by ATC to go around.

Details from the FAA on the AC759 incident, including positional data and time stamps.
Details from the FAA on the AC759 incident, including positional data and time stamps.

The timeline established by the FAA NTSB includes a number of interesting data points, any one of which likely should’ve caused the pilots to abort the landing. Ultimately they successfully did but a certain amount of luck appears to be involved in avoiding the disaster this time around.



From three miles out (just over a minute of flight time) the plane was lined up to land on the taxiway, not the runway. The incident was not a last minute shift in positioning.

Details from the FAA on the AC759 incident, including positional data and time stamps.
Details from the FAA on the AC759 incident, including positional data and time stamps.

The pilot reported seeing lights on the assigned runway and asked to reconfirm clearance to land. At that time the aircraft was still lined up for the taxiway and, according to FAA NTSB reports, not on the Airport Surface Detection Equipment Model X (ASDE-X)/Airport Surface Surveillance Capability (ASSC) radar screen. This is one of the systems ATC uses to track aircraft location when very close to the ground, places where traditional RADAR is less useful.

As ACA759 approached SFO, at 2355:52 PDT, the airplane flew too far right of course to be observed by the local controller’s ASDE-X/ASSC and was not visible on the ASDE-X/ASSC display for about 12 seconds.

At 2355:56 PDT, when ACA759 was about 0.3 mile from the landing threshold, the local controller confirmed and recleared ACA759 to land on runway 28R.

The controller did not have the plane visible on the surface radar screen and still cleared the landing, even after the pilot expressed some concern. That seems to me an unusual set of circumstances and probably worth further consideration during the rest of the investigation.

Details from the FAA on the AC759 incident, including positional data and time stamps.
Details from the FAA on the AC759 incident, including positional data and time stamps.

By the time the ATC controller issued the “Go Around” command the plane was already climbing. The pilots applied thrust after passing over UA 1, the first 787, around 85 feet above the taxiway. Roughly 2.5 seconds later the plane began to climb, having reached a minimum altitude of 59 feet over the taxiway, positioned between the A340 and the second 787 lined up for departure. The top of the A340 tail sits 59 feet above the ground; the 787 is about 3.5 feet shorter.



I held off on commenting for the most part because the altitude and positional data was mostly unclear in initial reports. The minimum altitude varied wildly and it was unclear just how close the A320 got to a catastrophe. Now we know, both from the data and the photos, that it was an incredibly close call. And, while the pilots certainly bear responsibility for lining up incorrectly, it also appears they did finally figure out they screwed up before ATC did. That’s a nice save.

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Seth Miller

I'm Seth, also known as the Wandering Aramean. I was bit by the travel bug 30 years ago and there's no sign of a cure. I fly ~200,000 miles annually; these are my stories. You can connect with me on Twitter, Facebook, LinkedIn and .

12 Comments

  1. Pilots were to blame? Sure! But why the pilot have to think they were wrong since ATC clearly gave them green light to land?

    Or maybe the ATC was overworked and underpaid, as those are common reasons for people in this industry who didn’t do their job but kept getting paid….

    1. The pilots were to blame because they were the ones flying the plane and lined up for the wrong runway. How would the ATC controllers (at nighttime) know that the plane was lined up with the parallel taxiway and not the actual runway? Radar does not show pin-point positions which is why visual approaches are generally done. This was a case of an unskilled pilot that nearly caused a major catastrophe. Even rookie pilots can make out what is obviously a runway vs a taxiway. The lighting is completely different and obvious. Runways actually have a long string of lights and arrows pointing towards the runway, while taxiways are nearly dark.

        1. Not sure if you are trying to troll. The ATC gave them permission to land on the *runway*. They certainly did not give the pilots permission to land on the *taxiway*.

          1. And ATC is also partly responsible for awareness of the location of the aircraft and noticing when they’re out of position.

            Again, shared blame. Lots of opportunities to fix the mess and fortunately one of them was taken.

      1. It is rare in these incidents that a single point of blame is assigned. If the plane disappears from the ATC ground radar that’s a red flag; it should not disappear if properly lined up. When the pilot identifies unfamiliar lights on the “runway” that’s a red flag that both the pilot and ATC should consider cause for a go around IMO. They both did eventually, but there was an opportunity to call it sooner, before the risk was as high.

        I’m familiar with the different lighting between a runway and a taxiway. That hasn’t stopped pilots from lining up on the taxiway and occasionally landing on them. It happens every couple years or so. And typically there is blame/responsibility to be shared in the process.

        I’m not saying ATC is THE cause of the incident. But I am suggesting that ATC contributed to the situation.

  2. What exactly does “minimum altitude of 59 feet over the taxiway” mean? Is that measured from cockpit height? From the bottom of the fuselage? The bottom of the landing gear? Usually when we’re talking about aircraft altitude, these differences are just rounding errors, but in a case like this, could really matter.

  3. Wow, what a mess. Agreed that ATC should have seen it, especially that the plane was lined up incorrectly miles out. I’m not a pilot but wouldn’t an onboard system also alert to the incorrect bearing?

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