The FAA expects that U.S. airlines will universally meet a
Jan. 1 deadline for the installation of GPS transponders on every aircraft,
setting the stage to realize more of the potential air traffic control (ATC)
benefits afforded by the network of GPS-based transmitters the agency finished
installing in 2014.
The system is known as Automatic Dependent
Surveillance-Broadcast, or ADS-B.
“Having the equipment universally in place is absolutely
essential for us to provide additional safety and efficiency benefits to people
who fly every day,” said David Gray, the FAA’s acting deputy director for
John Maffei, the FAA’s deputy director of NextGen Portfolio
Management & Technology Directorate, said that as of Dec. 1, 97% of
mainline U.S. aircraft had been equipped with the soon-to-be-required ADS-B
transponders. In addition, 95% of regional aircraft had been fitted with the
devices, and he added that all U.S. airlines have said they will meet the Jan.
The FAA’s move from radar-based flight surveillance to the
ADS-B surveillance system is a major component of the $22 billion NextGen air
transportation system modernization that the agency has been undertaking since
Aircraft equipped with ADS-B outbound transponders can be
tracked by controllers on a second-by-second basis, Gray said. In contrast, the
FAA’s current radar stations can only track a plane’s location somewhere
between every four to 12 seconds.
A graphic shows the communication process between aircraft, air traffic control, ADS-B ground transmitters and GPS satellites. Source: FAA
“That makes a real big difference for controllers when they
are working busy airspace in particular,” Gray said. He added that GPS
technology is also more precise than radar.
“When you couple those two things -- the
accuracy rate and the more frequent updates -- it
really allows controllers to have a sense about what an aircraft is doing at
any time,” Gray said.
Even without the mandate being in place, the domestic ADS-B
network has already begun to improve FAA controller capabilities, especially in
specific regions, Maffei said. One of those areas is the Gulf of Mexico, where
radar infrastructure could not be installed. As a result, aircraft traversing
the Gulf typically had to be separated by 10 minutes, approximately 80 miles.
Unlike radar towers, however, oil platforms in the Gulf can
support ADS-B transmitters. So ADS-B-equipped aircraft flying a route such as
Tampa-Cancun are now visible to air traffic controllers, which has enabled them
to reduce aircraft separation to as few as five miles.
Maffei said the visibility afforded by the domestic ADS-B
network has also enabled the opening of offshore routes between New York JFK
and Florida airports during busy travel periods.
In addition, the technology has improved ATC capabilities
“I interact with controllers all the time about ADS-B,” Gray
said. “There are lots of anecdotal stories about how the faster updates really
do make a difference, particularly in more crowded airspace.”
Safety, too, has been improved, according to Coleen Hawrysko,
operations program manager for the Civil Air Navigation Services Organization,
or Canso, whose members are air navigation system providers around the world,
including the FAA. She said the impacts have been most significant in remote
U.S. airspace, such as over Alaska and the Gulf of Mexico.
The FAA completed installation of ADS-B transmitters in 2014. Photo Credit: FAA
Still, the arrival of the actual ADS-B deadline sets the
stage for the FAA to commence formal airspace management changes that could
only begin once all commercial aircraft have been equipped with the transponders.
The first step, Gray said, will be a reduction in the
spacing of aircraft from five miles to three miles in what the FAA calls the
transition altitudes, between 10,000 and 25,000 feet. The condensed spacing
will first be implemented in Boston and Seattle this year ahead of an
anticipated broader rollout.
The FAA already spaces aircraft three miles apart below
10,000 feet. But expanding that three-mile zone up to 25,000 feet will allow
for more efficiency sooner as planes begin to bunch up ahead of arrival at
The arrival of the mandate deadline also sets the stage for
controllers to more effectively use parallel runways that are spaced closely
together, Maffei said -- for example, in Detroit, Los Angeles, San
Francisco and Seattle, where airports have runways in such proximity.
The FAA is in the process of completing a safety analysis on
the matter now, and then it will begin looking at the business proposition for
such improvements in conjunction with airports and airlines. Implementation
could start in about a year.
Other improvements will also be enabled. For example,
improved location reporting should mean controllers will be more accurate in
deciding when to order en-route adjustments, which are undertaken to prevent
aircraft conflicts based on location projections made 20 minutes ahead of time.
The FAA’s expectation that all aircraft will be equipped
with ADS-B also factored into the timing of a trial it will start in March
tracking aircraft over the Caribbean between Miami and Puerto Rico. That trial
will make use of the space-based ADS-B surveillance system launched in April by
the company Aireon, which is already active in the North Atlantic corridor
between the U.S. and Europe.
As the FAA mandate goes into place, airlines and air navigators
in Europe are preparing for the arrival of the ADS-B transponder mandate there
in June. According to Hawrysko, European operators are behind their U.S.
counterparts, with equipage levels currently at approximately 75%. Mandates are
also already in effect in various other countries, including Colombia, South
Africa, the United Arab Emirates, Canada and Australia.
She said she expects more countries to transfer from radar
to ADS-B-based tracking.
“I think it is going to continue to spread as [air navigation
service providers] become more mature,” Hawrysko said.