Fueling/Line
Tracking
All Movement
By Jodi Richards, Associate Editor
MKE first with ASDE-X system
Milwaukee's General Mitchell International Airport (MKE) air traffic control
is using an advance in technology allowing air traffic controllers to
better monitor activity on the runway and taxiway. The Federal Aviation
Administration-funded program involves utilization of ASDE-X, airport
surface detection equipment Model X, from Syracuse, NY-based Sensis Corporation.
Over the next three years, the system will be deployed to at least 21
airports across the U.S. with the intent of reducing runway incursions.
Marc Viggiano, Sensis
Corporation president of air traffic systems division, describes a runway
incursion as a loss of separation between two aircraft, or an aircraft
and a vehicle or person. "And it's not surprising that as airports
get busier, and we try to get more aircraft in and out of airports, keeping
them apart on the ground is a problem," he says.
Sensis Corporation has been in business for some 19 years. It has two
divisions: air defense systems and civilian air traffic control systems.
"The defense business is really how the company was started,"
he explains. "We started as experts in radar and systems integration
and then applied that technology to the civilian world."
According to Viggiano, "The ASDE-X program is an FAA program that's
primarily focused on safety, although the technology does have a number
of capacity and efficiency benefits."
Applying The Technology
ASDE-X combines multiple sensors to gather data. It then takes that data
and fuses it together for display on a color screen in the tower. "It's
an integrated system," says Viggiano. "Instead of just relying
on a single radar, [ASDE-X] uses a radar, a transponder multilateration
sensor, as well as an ASDE (airport surface detection equipment) sensor
and the existing airport radar. It takes all those sources and fuses them
together to make sure that you can do a good job of reliably detecting
the aircraft and also providing a positive identification by its flight
ID."
The ASDE-X system
is comprised of several pieces of hardware and software. "The sensors
themselves that actually detect the aircraft are the most visible, external
part of the system," says Viggiano. "The SMR (surface movement
radar) antenna is the part of the system that detects the aircraft. It
will see somebody whether your transponder is turned on or not. It will
even see unequipped snowplows, small GA aircraft, and large animals."
This antenna is mounted on top of the control tower, or possibly on a
stand-alone tower. It stands some one-foot tall, is 24 feet in length,
and spins at 60 rotations per minute.
The transponder multilateration is another piece, which is a cooperative
surveillance system that provides position and identification of all transponder
equipped aircraft. Says Viggiano, "They are small cabinets, that
can be mounted outdoors, the size of a small dormitory refrigerator, and
a little antenna that looks like a cell tower antenna, which doesn't move.
It's stationary and typically mounted on an existing structure."
Generally, he adds, there are about eight of those sprinkled around the
airport.
Data from the sensors are then fed back over a communications system,
typically telephone lines or existing networks, explains Viggiano. The
communications are fed back to the equipment room, which is usually in
the control tower. All the processing takes place there, while the surface
movement radar tower can be located several kilometers from the control
tower.
According to Viggiano, the radar is only looking at the movement areas,
- runways and taxiways. "So if you have a snowplow on the runway,
the radar will pick it up, however it won't tell you what it is. It will
be a blob." Although, an external antenna, called a Veelo, can be
mounted to a vehicle. "For example, if you want to keep track of
your snowplows, fire trucks, or tugs, you put one of these units on it
and it will show up on the same [ASDE-X] system - not only where it is,
but who it is."
The number of sensors at a given airport depends on the physical layout
of the airport, Viggiano explains. "It's a function of its actual
geometry - not just how big it is, but also where the runways are."
A site survey is done to determine the needs and appropriate locations
for the sensors.
Milwaukee's Appeal
MKE was an excellent location for testing the system, according to FAA
officials. "I think that one reason that Milwaukee was selected,"
says Wanda Adelman, FAA air traffic manager, "is because of the climate.
We've got really warm and really cold and a lot of the fog that comes
off the lake. [There are] many days that we can't see the runway because
of the fog, rain, and clouds, so it's a good place to be able to test
in all types of different weather."
MKE has been the test site for surface radar as it's been developed over
the past decade, according to Adelman.
Externally mounted antenna
She says on low visibility
days, without ASDE-X, if an aircraft is arriving, ATC has to wait until
the aircraft lands and then taxis off the runway and the pilot tells ATC
that it is off the runway before controllers can clear the next departure
for takeoff.
"With the ASDE-X, you can see the arrival coming in on the ASDE-X
display. Once they're past the threshold, you can put the next aircraft
into position and hold and then you can see the arrival taxiing off the
runway, onto the taxiway, and you can verify that your runway is clear,
even though you can't see it out the window, you can see it on the display."
Tony Molinaro, FAA spokesperson, says it's hard to say for sure what impact
the system will have on reducing runway incursions. "It's hard to
measure safety in those areas. But one of the major goals of the FAA is
to improve safety at all facilities in the airport. And this is one of
those systems that really focuses on ensuring a safer environment. Will
it eventually result in fewer runway incidents? We expect so, but it's
too early to see what that affect is yet."
According to Viggiano,
the FAA plans to deploy ASDE-X at 34 airports across the nation, and the
first 21 are already contracted at a total value of some $100 million.
He expects these airports to be equipped with the system by the beginning
of 2007.
The cost of deploying the first system at MKE was some $27 million, says
Viggiano, which includes training users, software, hardware, research,
development, and testing of the equipment.
Viggiano says one of the biggest advances in technology that has allowed
a system like this to become available is the use of multilateration.
However, he is quick to add that "beyond the technology, it's a recognition
that maximizing the safe utilization of airport runways is a key resource
that we have to pay more attention to and make sure we get the maximum
out of it that we can in a safe way."
Future Upgrades
Like any other technology, airport surveillance systems are always being
improved upon. Viggiano says Sensis has "a fairly steady stream of
upgrades coming. One that's getting a lot of interest right now is taking
the same basic principle and applying it to aircraft that are 30 or 60
miles away from the airport. So you can get radar coverage where in the
past you had only procedural voice control."
Another advancement Viggiano sees is the ability to have a datalink from
ASDE-X to the cockpit. "So a pilot not only knows where he is but
sees all the other people around him on a display in the cockpit."
The FAA is also engaged in researching other technologies, including AMASS
(airport movement area safety system), designed for larger facilities.
"It's another screen in the tower that tells a controller how close
his airplanes are," says Molinaro. "The difference [between
AMASS and ASDE-X] is that AMASS also offers oral alert - the computer
will alert the controller if two planes are getting too close on the runway."
He adds that the two systems may some day be merged together.
Lights Play New Role in Runway Safety
A simulation
study is underway at NASA Ames SimLabs to investigate safety effects
of standardizing the use of
aircraft lighting during taxi operations.
The Aircraft
Landing Lights to Enhance Runway Traffic Safety (ALLERTS) project
addresses a recommendation of the Runway Incursion Joint Safety
Implementation Team to develop Standard Operating Procedures for
aircraft taxi operations specifically related to aircraft lighting.
The purpose of the ALLERTS project is to investigate the safety
effects of using aircraft exterior lighting to convey messages in
the airport environment. Two specific procedures are being explored:
the use of landing lights to indicate that aircraft are cleared
to depart and the use of all exterior lights to indicate that aircraft
are crossing the active runway. The objective being to determine
whether standardizing the use of aircraft lighting will reduce runway
incursions and accidents, and increase pilot situational awareness.
The experiment is being conducted in the B747-400 flight simulation
at SimLabs' Crew-Vehicle Systems Research. In each simulation, pilots
are instructed to taxi, depart, or land, and researchers gather
subjective and performance data on the crew. In half of the scenarios,
they encounter another aircraft that makes an error which could
result in an incursion or accident if not detected by the subject
crews.