What Happened Last Night at LaGuardia.

There is a lot we don't know about the tragic collision last night. But we already know enough to be very concerned.

Last night at LaGuardia. The two Air Canada pilots died; many other people were injured or will have their lives changed forever. (Photo Spencer Platt/Getty Images.)

It takes a long time to know the why and how of aviation disasters. The purpose of this post is to point to several early sources that clarify the what of last night’s fatal collision at LaGuardia airport, LGA.

For reference I offer the diagram below. It’s an official FAA chart of the runway and taxiway layout at LGA. The annotations are by me.

Here’s the user-guide:

—Light green, coming in from the southwest corner, is the approach path of the Air Canada regional jet. This is the one that hit the fire truck, and whose two pilots were killed. In the air-traffic discussion it’s addressed as “Jazz 646.” It had been cleared to land and, as the drama begins, was touching down on Runway 4, heading roughly northeast.

—The red box on the left shows the LaGuardia fire station. All big airports have them. The red arrow headed to the right is the route of a group of fire trucks dispatched to help a United airplane (shown in magenta) at the other side of the field. The United plane needed to get its passengers out of the plane in a hurry, because of an odor that had sickened its flight attendants. The fire trucks, with ladders aboard, had been cleared to cross Runway 4 at Taxiway Delta, at the point where the red and green arrows touch.

—This precise point is where the collision occurred. The plane, just beginning to slow after touchdown, crashed directly into the lead fire truck that was crossing its path. The plane’s momentum carried the truck-plane wreckage further up the runway, roughly to Taxiway Echo, marked E.

—The small blue arrow to the right of the impact point, is the approximate location of Frontier 4195, which was waiting its turn to be cleared across Runway 4 so it could taxi for takeoff.¹ I mention this Frontier flight, and the other from United, because, as you’ll see, each played a role in the drama. United, because the reason the fire trucks left the station was to help that aircraft. Frontier, because the controller’s first urgent “Stop! Stop!” call appeared to be addressed to Frontier, followed by many Stop! STOP!!! calls to the lead fire truck.

Now, the guides and videos.

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VASAviation with its illustrations.

I frequently refer to videos from VASAviation, run by a professional pilot based in Spain. These do an excellent job of matching audio with images, to give an idea of where pilots and aircraft are, and what they’re saying and doing, at crucial moments of flight. Sometimes the images and maps are approximations, but they stand up well in offering a general perspective.

You can dig right into this six-minute VASAviation re-creation below. I very highly recommend it. People who follow aviation will find it full of inside-baseball cues and details. I think almost anyone will find it compelling. Below the video, I’ll give a summary of the participants and the dialogue.

-The airplanes.

You’ll hear controllers address or refer to United 2384, the flight that declares an emergency before takeoff because of the unknown odors. And Frontier 4195, an outbound flight that is being directed toward what becomes the collision zone, as part of its progress toward its planned takeoff point. And Jazz 646, the Air Canada flight that touches down into tragedy. Later in the audio you’ll hear instructions to many other flights in and around LGA, mainly telling them to go elsewhere or “go around” after the crash, because the runway is closed (and then the whole airport).

You’ll also hear discussion with Truck 1, the lead fire truck.

-The controllers.

You’ll hear a number of voices, including managers at LGA trying to find an empty gate for the distressed United flight; “approach” controllers handling planes that are being told to go around; and what I think are two or more distinct voices in the LGA control tower.

But mostly you will hear one LGA controller, who has many claims on his attention all at once.

-The incredible juggling act.

Through most of the recordings, this one LGA controller appears to be doing many jobs. He is working both “Tower” and “Ground” frequencies late at night at a busy airport. Which means, listening to two separate radio frequencies at the same time, and broadcasting on them in turn. On the tower frequency, he is clearing planes for takeoff and landing, and is in charge of them while they’re on the runways. On the ground frequency, he tells pilots where to taxi, and what runways or taxiways they may cross.

The same controller is also talking on a land line with other LGA officials. He is dealing with the crew in the fire truck. This means that he is, as a partial list, simultaneously in charge of:

(a) the normal, busy inbound/outbound traffic at LGA;

(b) the United 2384 crew that has a sudden problem to solve;

(c) the airport officials trying to find a place for United passengers to disembark;

(d) the team in the lead fire truck;

(e) Frontier flight 4195 as it taxis for departure;

(f) inbound Jazz 646 as it prepares to land; and

(g) other stuff we probably can’t see or hear.

Controllers excel in multi-tasking. But even for a busy airport this is extreme. Imagine doing this yourself. With such high stakes.

-The crucial moment.

The controller, in his “ground” role, clears Truck 1 to cross Runway 4, on taxiway Delta, to go help the United flight.

In his “tower” role, he clears Jazz 646 to land on that same runway.

Then, back in “ground” role, he tells Frontier 4195 to “stop” as it is heading toward this same taxiway Delta/Runway 4 intersection, presumably until the inbound flight has landed and the lead fire truck has cleared.

At the last minute, he sees what is happening. He yells “Stop! Stop!” initially addressing this to the Frontier flight. Then he starts staying “Truck 1, Stop! Stop! Stop!” And by that point it is too late.

Watch, again, the VASAviation video with that in mind. Or the one below, from Pilot Blog. I recommend starting this second one at about time 2:30. It goes in detail into possible mis-communication issues, especially why the fire truck crew might not have realized that the urgent STOP!!! was meant for them.

And here is an audio-only rendition:

Also I see just this moment that the reliably expert Juan Browne has put up an analysis on his Blancolirio site.

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We don’t know what we don’t know. But we do know this.

First-day assumptions about any air disaster tend to be wrong. We don’t know what the next days or weeks or months might reveal.

But we know two things about implications for commercial aviation, with its decades of exceptional safety. And one more thing about the different world of military aircraft.