State breaks ground for GPS flight system

Within five years, pilots across the nation will be able to rely on satellite-based GPS rather than ground-based radar to determine where they are in relation to other aircraft.

But in a quiet rollout that a civilian contractor began last fall, a Global Positioning System project called ADS-B has become operational in parts of Florida.

ADS-B, which stands for Automatic Dependent Surveillance-Broadcast, is a key element of the $20 billion Federal Aviation Administration NextGen plan to overhaul the nation's aging and overburdened air traffic control system by 2020.

It's a project with both critics and challenges amid the promise of an evolutionary way to manage air traffic, from high altitudes down to the airfield level at some major airports.

Today, pilots of aircraft equipped with ADS-B flying between Tampa and St. Cloud, near Orlando, south to Key West can get the same information on cockpit displays that air traffic controllers see.

In addition, the GPS pinpoints an airplane's location to controllers more quickly and accurately than information from radar returns. The new system generates data every second, compared with four seconds for airport terminal radar, such as the unit at Tampa International Airport, and more than 12 seconds for long-range radar at seven Florida sites and others nationwide.

Eventually, the system could enable controllers to position aircraft closer to one another to contend with increased traffic, plus allow the FAA to cut costs by shutting down some radar.

A benefit will be ADS-B coverage over the Gulf of Mexico, where a communications "black hole" hinders flights between Texas and Florida, and low-level helicopter flights to and from oil rigs operate without air traffic control.

Safety among benefits

The basic elements of ADS-B are GPS satellites, a transceiver in the aircraft and ground-based stations.

The basic system uses the aircraft transceiver to take its GPS-tracked location from a satellite and combine it with information about the speed, altitude and type of plane.

That data is transmitted to one of 800 automated ground stations nationwide that look like cell phone towers. Eleven are installed in Central and South Florida, including one in Lakeland.

The information flows through an ADS-B control station to FAA controllers, who observe the ADS-B data along with information from radar, a system that must be retained as a backup and for national security. At the same time controllers monitor the flights and maintain radio contact with pilots, pilots also get position data from other aircraft with ADS-B in the vicinity.

An optional function sends weather data and locations of aircraft without ADS-B through the control and ground stations back to the aircraft.

"ADS-B brings safety benefits along with operational efficiencies," said John Kefaliotis, program director for ITT Corp. of White Plains, N.Y., which is producing the ground equipment and will operate the system until 2025 under a $1.8 billion contract.

A December midair collision over the Everglades between two small aircraft flying under visual flight rules might have been avoided if the pilots had a cockpit display showing nearby aircraft, Kefaliotis said.

"We checked the data we had from that area and saw what happened," he said. "That accident in which four people died certainly would not have occurred if the planes had been equipped with ADS-B."

The associate dean for research at Embry-Riddle Aeronautical University's college of aviation in Daytona Beach said the safety promise is the biggest benefit for the university, which operates a fleet of 100 training aircraft in Florida and Arizona.

"ADS-B enables me to track all of our aircraft from my laptop," said Steven Hampton, who also directs Embry-Riddle's research for the FAA. "The ability for pilots to see other aircraft minimizes flight time, saving fuel and reducing carbon emissions."

United Parcel Service is the only carrier so far to equip its fleet of 262 aircraft with ADS-B. Though the system is not used yet on UPS flights to St. Petersburg-Clearwater International Airport, its local hub, it helps the carrier merge approaches during peak landing periods at its hub airport in Louisville, Ky.

"The test data that we are generating and validating, both for ourselves and the aviation industry, show that ADS-B offers promise in safety and efficiency, as well as environmental benefits," said Mike Mangeot, UPS Airlines public relations manager.

UPS has found it could increase the number of its planes that land at Louisville by 10 percent to 15 percent, Mangeot said.

UPS also found that ADS-B allowed a "continuous descent" landing approach that can reduce nitrous oxide emissions by 34 percent, noise by 30 percent and fuel consumption by 40 to 70 gallons per landing. Instead of a conventional approach in which aircraft must accelerate and slow down as controllers move them into a landing queue, the new system enables an aircraft to glide in with engines at idle thrust.

Equipment costs

But it will be some time before other carriers decide whether to equip their aircraft with ADS-B, as they evaluate the costs and benefits.

The U.S. Department of Transportation reported that the basic equipment could cost $32,000 to $174,000 for commercial airliners and from $7,600 to $10,900 for general aviation aircraft.

Fully equipped aircraft could cost $162,000 to $670,000 per commercial aircraft and from $10,444 to $29,700 for smaller planes.

Under a proposed rule, only aircraft flying in certain airspace, such as higher than 18,000 feet or near congested airports, will be required to be equipped with the basic ADS-B by 2020.

The FAA is not mandating aircraft to have the ADS-B function that would receive and display traffic information, including the location of planes not equipped with the system.

In addition to costs and the long lead time the FAA has proposed for implementing the system, security is a potential issue.

The DOT raised security concerns in a 2007 Inspector General's report, saying vulnerabilities should not be discussed openly, but needed to be resolved.

ITT's Kefaliotis defends the system's security, saying encryption of data and other security measures are built in.

Still, in March 18 testimony before a congressional committee, the president of the National Air Traffic Controllers Association said the NextGen system relies on technology that could be vulnerable to natural disasters and criminal or terrorist acts. He called for redundancy to be built into ADS-B or maintaining ground radar as a backup.

"While we believe ADS-B has tremendous potential and is capable of providing precise, accurate and instantaneous information on aircraft positions to air traffic controllers, it is particularly vulnerable due to its single-site source" satellite, Patrick Forrey said.

The FAA's challenge is how to get enough funding for its annual budget, including ADS-B, while providing a stable, long-term funding stream to accomplish the transformation from radar to ADS-B.