The video above is the view from the tower at San Francisco International Airport on the night of July 7, 2017. You can observe a Frontier Airlines taxing, passengers boarding a American airlines flight, and other insignificant stuff. However, if you pay attention to the top left corner, you will see a plane appearing to approach the taxiway, with four other planes. Towards the end, the said plane barely misses the tail of the second plane, and prevented what could have been the worst air disaster in history. This is the story of Air Canada Flight 759.

Earlier that evening, at Toronto Pearson Airport, Air Canada Flight 759, an Airbus A320(Pictured Above), was getting ready for their flight to San Francisco, when the pilots received their NOTAM, or Notice To Airmen, which lists out of the ordinary, or exceptional details for the flight. Inside, towards the bottom, there was a notice stating that runway 28 Left in San Francisco would be closed for maintenance shortly before midnight. However, the NOTAM’s are long, usually several pages, and the runway closure was in a small paragraph. Although the copilot didn’t see it, the pilot did, but thought the plane would make it before the closure. And besides, the warning of a thunderstorm during the flight seemed more pressing, so the pilots didn’t think much of the runway closure.

Around halfway through the flight, the plane experienced the thunderstorm, so they started to go around the storm, because the thunderstorm might be a problem with the flight. However, after the storm, the pilots started to feel tired, as it was past midnight at Toronto time. This is normal, but, for pilots, this is cautionary, because it affects their decision making and makes them think more about sleeping than landing.

But, several hours later, they were flying over California towards San Fran. Because the skies were clear, the San Francisco tower granted the flight visual approach, which is where one guides themselves to the runway based on what they see. This visual approach was over the bay, to reduce noise pollution, and when coming in, the plane looks slightly to the right. They also received their ATIS, or Automatic Terminal Information Service, which gives info about things at the airport, like weather, or a runway closure.

At this point, both pilots, who had landed at San Fran before, think that they will see two parallel runways, but due to the runway closure, the lights of 28 L have been turned off, so planes don’t accidently land there. So, they accidently think that runway 28 R is runway 28 L, and taxiway Charlie is runway 28 R. They start veering towards the taxiway.

On the taxiway, 4 other planes were preparing for takeoff:

-United Flight 1, a Boeing 787 flying to Singapore

-Philippine Airlines Flight 115, a Airbus A340 flying to Manila

-United Flight 863, a Boeing 787 flying to Sydney

-United Flight 1118, a Boeing 737 flying to Cancun.

And the Air Canada flight was flying towards all 4 of them, all containing 1091 passengers. Assuming the Air Canada flight did crash, it would cause the largest air disaster of all time, far greater than the Tenerife disaster, where 583 people were killed when two Boeing 747’s collided with each other.

However, isn’t it kind of dumb that the Air Canada pilots didn’t notice that they were landing on a taxiway? Well, yes, but, they were also tired, and, because the brain is wired to recognize patterns, they were sure they were on the correct runway. However, just to make sure, they could have turned on the ILS, or Instrument Landing System to make sure they were on the right path, but they chose not too.

Still descending on the taxiway, the Air Canada flight reported seeing lights on the “Runway”, and asked the tower if they were clear to land on 28 R, which the tower said they were. Now, I already mentioned before that due to the visual approach, the plane will look slightly to the right, but both the tower and the planes are confused on why it still looks so far right, when the planes on the taxiway realize that Flight 759 is coming strait for them. Quickly, UAL 1 speaks up:

UAL 1: Where is this guy going?

UAL 1: He’s on the taxiway

At this moment, PAL 115 turns their landing lights on for clearer visibility on the taxiway. Air Canada flight 759 starts to realize the disaster that’s about to happen, and prepares to go around. However, while pulling up, the Air Canada flight barley misses the tail of PAL 115. But, it was over, and the worst disaster in air history has been avoided.

Because this is a pretty big thing to screw up on, the National Transportation Safety Board launched a investigation into the incident, and made a list of recommendations. First, in the cockpit and the towers, there has to be a warning system to make sure the plane is definitely landing on the runway. Also, at San Fran, visual approaches at night aren’t allowed when a runway is closed. Finally, there has to be two air traffic controllers in the tower. With this, the world was reminded the dangers of miscommunication at airports, as that also happened at  Tenerife.