Image: Cockpit navigation system
Rockwell Collins
By presenting speed, energy vector, power, altitude and navigational information on a clear screen directly in front of the window at eye level, head-up guidance systems help keep the pilot's eyes looking out of the cockpit. This aids the pilot's situational awareness and improves safety.
By
updated 7/3/2007 6:17:06 PM ET 2007-07-03T22:17:06

Whether you're more used to flying in an airliner or in a private jet, you may feel you're getting more than your share of flight delays.

It's not just you. Delays are mounting as air traffic increases, particularly in the United States. A big part of the problem is that the U.S. air traffic control system is based on ground-based radar technology that is increasingly incapable of handling the growing volume of traffic — particularly in bad weather.

But new navigation, communication and display technologies being installed in the flight decks of today's airliners and business aircraft are helping solve the problem. These technologies help pilots fly their aircraft more efficiently and safely and help controllers keep flights on time.

Radar signals degrade over distance, so determination of an aircraft's position becomes less reliable the further away it is. To preserve safety, controllers must keep aircraft well apart.

The faster aircraft are flying, the farther apart they must be kept. In radar-controlled areas, aircraft cruising at the same high altitude must be separated by 5 miles. Over oceans, where radar coverage doesn't exist, aircraft at the same altitude are kept 50 miles apart, said FAA spokesman Paul Takemoto.

Bad weather conditions exacerbate the problem and force controllers to increase separations.

By 2025, U.S. passenger numbers will more than double from today's 740 million. "We need to transition from the ground-based radar system," said Takemoto. "It's decades old and it's totally maxed out."

The FAA's Next Generation Air Transportation System (NextGen) will use satellite communications instead of radar. By 2020 all U.S. aircraft will be required to have equipment that uses the system.

A cornerstone of NextGen will be a technology called automatic dependent surveillance - broadcast. Several times a second, every aircraft will digitally broadcast information obtained from its transponder regarding position, altitude, direction of movement and the aircraft's horizontal and vertical speed.

ADS-B uses two different satellite networks. Each onboard unit determines the aircraft's position extremely accurately using GPS satellite signals. Then it digitally broadcasts this and other information to telecommunications satellites to reach all other aircraft within 150 miles, as well as ground stations.

Every aircraft's instrument displays will process ADS-B information and combine it with overlays of terrain topography and weather conditions to produce detailed pictures of the surrounding airspace. At the airport, ADS-B will let aircraft see and avoid each other on runways and taxiways.

Air traffic controllers and pilots will be able to identify potential safety problems quickly and avoid them. Using ADS-B, separations between aircraft can be reduced, airplanes will be able to fly more direct and efficient routes and the increase in U.S. air traffic will be accommodated.

ADS-B is already well-tested and has proved highly effective. In Alaska, where communities rely on small aircraft for all their transport and supply needs, ADS-B has been adopted statewide. It has produced a 40 percent drop in Alaska's traditionally high accident rate.

UPS, a pioneer in developing ADS-B, has fitted units to 300 of its jets so that when they converge on its Louisville, Ky. hub each evening they maintain optimum separation and all can land on time.

Hundreds of oil rigs in the Gulf of Mexico are served by helicopters but are outside radar control. The FAA and the Helicopter Association International are working to install ADS-B ground stations on rigs to improve safety.

Meanwhile, advances in flight-deck instruments are making air travel safer and more reliable. The traffic alert and collision avoidance system (TCAS) and the enhanced ground proximity warning system (EGPWS) have become so invaluable that every country in the developed world has now made these systems mandatory on its airliners, said Flight Safety Foundation expert J.A. Donohue.

TCAS uses an airliner's transponder to show other aircraft in the vicinity information about its identity, position, speed and direction. The system alerts pilots of aircraft nearby, warns them if another aircraft is within 30 seconds' flying time and advises a specific avoidance maneuver if a collision becomes likely.

Two airliners collided over southern Germany on July 1, 2002. Authorities investigating the accident found that had the captain of one aircraft taken the avoiding action his TCAS unit advised rather than following the controller's instruction, they wouldn't have hit each other.

One of the leading causes of airliner accidents is controlled flight into terrain. This occurs when pilots aren't aware their aircraft is closer to the ground than it should be, usually in bad visibility.

EGPWS - which compares an aircraft's GPS-derived position with a digital topographic map to warn pilots when they are in danger of flying into terrain - is so effective that no aircraft fitted with it has ever had a CFIT accident, said Donohue.

Other new flight-deck technologies are reducing the numbers of delays and accidents caused by bad weather. Modern weather radars give pilots a 20-mile offset view that shows them how high all the clouds are around the aircraft, allowing pilots to avoid strong convective formations.

Enhanced vision systems use infra-red imaging to let pilots see the runway below at night and in low cloud. Synthetic vision systems - which use digital terrain databases, like EGPWS - help pilots complete landings in poor visibility.

"Basically the aircraft knows what it should be seeing and projects an image of what to look for," said Donohue. "It enhances situational awareness when you finally get through the clouds."

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