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William Hill |
This article originally appeared in IFR MAGAZINE and is reprinted here by permission of Belvoir Publications.
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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:
-
The Metroliner was taxiing onto a runway being approached
by another airplane;
-
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,
-
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.
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