On Situational Awareness

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Do you find yourself baffled by what's going on around you? The clues to ATC's next move are there for the listening. The author uses the fatal 1991 collision of a USAir 737 and a Skywest Metroliner at LAX as an instructive example.

I was working the early morning shift at the Air Ambulance Shop when I happened to read one of the many articles written about collisions between aircraft on what controllers call movement areas but what pilots know as runways and taxiways.

One of those articles mentioned the well-publicized collision between a USAir 737 and Skywest Metroliner in position for takeoff at Los Angeles International one winter night in 1991. From the accident report, it's quite apparent that the radio chatter that night offered plenty of clues that should have alerted both flight crews to the danger looming on the runway.

Traditional training doesn't reveal how these clues can be used. Did your instructor school you in the basics of air traffic procedures, to the extent that you know how a controller sets up an arrival sequence and how to tell just from listening where you fit into the flow? Serious students of the AIM and readers of the ATC manual (7110.65) can puzzle it all out, but neither publication puts things into context in terms that pilots (and controllers) can put to use.

Clues Are There

With this in mind, consider the LAX accident as an instructive example. Departing LAX, the Skywest flight had received its clearance to taxi to the runway. As is typical of commuter crews, the Skywest pilots probably had a lot of work to do in a short period of time and to keep things rolling, they asked for an intersection takeoff.

Skywest 569: "Skywest Five Sixty Nine at (taxiway) 45, we would like to go from here if we can."

Tower: "Skywest Five Sixty Nine, taxi up to and hold short of 24 left."

Skywest 569: "Roger, hold short."

What was going in the Metroliner cockpit? Probably all that remained was to taxi into position, perform whatever line-up checks required by the company and await takeoff clearance. So far so good. But what else? At a busy place like LAX, there's constant activity and most of it will be described in some fashion by radio calls between aircraft and tower and ground positions. Sometimes movements will be obvious; sometimes not.

Holding short of a runway is a good place to start forming a mental picture of what's happening, what the old time controllers call "the flick." If you're on the tower freq, listen for landing and takeoff clearances. Who has been cleared to and from what runways? Who's holding short in the departure queue? Who has been cleared to cross an active runway or told to hold short? Some pilots make a habit of listening to tower on one radio, ground on the other. In the case of Skywest, the clue came from a routine position report from an inbound flight:

USAir 1493: "USAir Fourteen Ninety Three inside ROMEN (the outer marker for runway 24L)."

In a perfect world, the Skywest crew would have made a mental note of this and maybe even discussed the fact that an airplane was about to land on the runway they would soon depart from. Evidently, they did not.

Tower: "Skywest Five Sixty Nine, taxi into position and hold, runway 24L, traffic will cross down field."

Skywest 569: "'Kay, 24L position and hold, Skywest Five Sixty Nine."

No One Noticed

Looking a little deeper into what's happened thus far, there are three situational issues to consider:

  1. The Metroliner was taxiing onto a runway being approached by another airplane;

  2. They had been warned about traffic crossing downfield as if to suggest that once it was clear, they'd be given takeoff clearance; and most importantly,

  3. The tower had not acknowledged the first call-up of the USAir Boeing.

Did that mean that the local controller didn't hear the call or was too occupied to acknowledge? Was she aware of the conflict she had created on runway 24L or was she just pushing tight gaps on departures?

Forty five seconds later, the Metroliner was still in position on the runway, the downfield traffic had long since cleared. The USAir Boeing again called, now well inside the marker. In just short of a minute, it would have eaten up close to half the distance from the marker to the runway threshold. Had the Skywest crew mentally noted the Boeing's position from the initial radio call, they'd have known where it was, even though they couldn't see it. They could have queried the controller or, if the freq was too busy for that, simply taxied clear to sort things out from the safety of the taxiway.

Twenty four seconds later, the tower cleared the USAir 737 to land on runway 24L and still the Metroliner stood parked on the runway, awaiting takeoff clearance. Incredibly, another full minute passed before the tower cleared yet another airplane-a Southwest 737-into position and hold on the very same runway, 24L. Where was the USAir 737? It must have just passed the threshold or the controller wouldn't have cleared the Southwest flight into position and hold. Had the controller forgotten the Metroliner?

Indeed she had. The USAir Boeing was only seconds from colliding with the Metroliner, whose crew must have heard the traffic picture developing but either misunderstood its implications and were too distracted or indisposed to ask. For its part, the USAir crew seemed unaware of the traffic picture as well. Even though they had to call twice to get the tower's attention and would have certainly heard the tower clear the Metroliner onto runway 24L, the implications simply didn't register.

What To Do

Later investigation revealed that a contributing factor in this accident was the fact that the tower controller's view of the intersection where the Metroliner was holding was obscured. But even at that, at a big airport, it's hardly impossible for a controller to lose track of an airplane in the sea of taxiway and runway lights at night. This is particularly true of GA aircraft operating in a terminal where controllers are accustomed to seeing the bright lights and multiple strobes of air carrier aircraft. Whether in the air or on the ground, a small aircraft is at a distinct disadvantage when operating into a major terminal and mixing with faster, heavier traffic. As we've reported before, sequencing a 100-knot airplane into a conga line of airliners doing 140 knots requires skill and planning on the controller's part. For the pilot, it may mean flying a much faster approach than normal and perhaps breaking off at the last minute to land on another runway.

You can learn to anticipate this by listening carefully as the controller sequences his arrivals. When the controller issues a heading and an altitude to another airplane being vectored for the same approach you're headed for, form a mental picture of where that airplane is and what your sequence is relative to that traffic. If the airplane ahead of you got a 120-degree heading and a descent to 2000 feet followed by an approach clearance, you'll probably get something similar. Or maybe the controller has bunched his charges up too tightly on the localizer and is sorting things out with vectors and speed control. Don't be surprised if you get vectored through the localizer for spacing or even turned out for another approach to a different runway.

On the ground, don't be in too big a hurry to get underway when departing. Listen to ground control for a few minutes to form a mental picture of where other traffic is on the airport. And remember, at a big airport, ground may have trouble seeing you and may not know exactly where you are. If you sense a potential conflict, speak up and tell the controller exactly where you are in terms he'll understand: "Mooney Nine Eight Bravo is on Alpha taxiway at Charlie One."

Since the LAX accident, some pilots follow the policy of not accepting position and hold clearances at night and, even during the day, positioning on the runway at an angle such that traffic approaching the threshold is clearly visible. To that, we might add the suggestion that considering jet blast, the run up pad at the runway can be a dangerous place. If you can, run-up elsewhere and be ready at the runway.

If, by all of this, you think that I'm suggesting you should become the keeper of your brother, you're correct. That's far preferable to being in the center of a fireball just past the threshold of the active runway.