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As United Airlines
Flight 1193 touched down in Denver on Feb. 2, a snow plow blundered onto
the runway in front of the speeding jet.
Up in the airport's tower, controllers were unaware
of the danger. The safety system designed to track planes and vehicles on
the ground never issued an alert, according to a report by the National
Transportation Safety Board (NTSB). Luckily, the United pilots spotted the
plow in time, narrowly averting a crash by jamming their brakes and coming
to a full stop on the runway.
Because the runway safety system in use at large
airports like Denver has repeatedly failed to alert controllers to
hazards, the Federal Aviation Administration is scrapping it and turning
instead to a modernized digital version that does a better job of
monitoring planes on the ground.
The new system, however, may be no better at
preventing collisions between planes and ground vehicles.
Even though the system, Airport Surface Detection
Equipment Model X (ASDE-X), is designed to use new technology to track
plows and other ground vehicles with great accuracy, the FAA is not
allowing ground vehicles to be equipped with the radio identification
beacons necessary to optimize the system.
"The technology is there. It was developed for this
and it should be used," says Brad Rosenthal, who heads the controller's
union chapter at Lambert-St. Louis International Airport. "We are trying
to keep vehicles and equipment off of these … runways."
The FAA acknowledges it has blocked radio beacons
from being put on airport vehicles, but says it is doing so for a good
reason: The beacons could interfere with the ability of radar to track
aircraft around an airport. The agency is working on dozens of fronts to
try to improve runway safety, spokeswoman Laura Brown said.
'Potential for catastrophe'
The deadliest plane accident in history occurred not
in the sky but on the ground.
On March 27, 1977, two Boeing 747s slammed into each
other at an airport in the Canary Islands when the pilots on one jet
mistakenly attempted to take off in fog while another jet was on the
runway. The impact and fires killed 574 people.
"This is where the greater concentration of aircraft
is at any time while passengers are on them," NTSB Chairman Mark Rosenker
says. "This is where the potential for catastrophe is greatest at this
point."
A review of the most serious FAA and NTSB runway
incident records show that the dangers are not restricted to crashes
between planes:
•On May 25, an American Eagle ATR-42 twin turboprop
was approaching Miami International Airport when a tug operator pulled a
Boeing 747 onto its runway. Only quarter-mile away, the Eagle pilots saw
the jet and aborted their landing, passing only 200 feet above the other
plane.
•On Nov. 30, 2004, a Mitsubishi MU-2 turboprop
attempting to takeoff at Philadelphia International Airport struck an
airport tug towing a Boeing MD-80. The MU-2 suffered substantial damage,
but no one was hurt.
•On Sept. 19, 2003, a dump truck that was part of an
airport construction project drove across a runway at Houston Hobby
Airport. At the same moment, a Southwest Airlines Boeing 737 arrived at
the runway for landing. The Southwest jet flew directly over the truck.
The FAA estimated the two were separated by 106 feet.
Best system available
ASDE-X is not a perfect solution, but it is superior
to anything that currently exists, according to the FAA, NTSB and
controllers. Unlike the system at Denver, known as Airport Movement Area
Safety System, ASDE-X is capable of tracking vehicles and planes in all
weather and it is far less prone to interference. Controllers at Atlanta's
Hartsfield International Airport have grown so reliant on ASDE-X that the
number of landings and takeoffs drops when it is switched off for
maintenance, said Gary Brittain, president of the controllers' local
union.
Without radio beacons on all vehicles, however, the
system has a blind spot.
Capt. Mitch Serber, the ground safety chairman of the
Air Line Pilots Association, said his union supports swift installation of
ASDE-X in as many airports as possible. He says vehicles should get
beacons soon.
"If we're going to get 100% out of our investment, we
are going to have to equip ground vehicles," he said. "The severity and
consequences are something we can't afford to
ignore." | 
