Software to avert airport delays

NASA and Honeywell Inc. have developed technology that may help prevent frustrating delays at some of the nation's busiest airports.

Software developed by NASA, the Honeywell Technology Center and Honeywell Airport Systems solves a unique problem at airports that have parallel runways spaced as close as 2,500 feet apart. During low visibility, air travel switches to instrument approach conditions, and under such conditions, airports with parallel runways less than 4,300 feet apart - including the Minneapolis-St. Paul, Detroit, Seattle and Memphis, Tenn., airports - must close one runway.

When an airport shuts down a runway, the number of aircraft that can land per hour drops from 60 to 45, a decrease that causes significant delays, said Bill Corwin, research program manager at Honeywell Technology Center in Minneapolis.

The software that the NASA/Honeywell team developed enhances an aircraft's navigation and communications systems. The software, called Airborne Information for Lateral Spacing and Closely Spaced Parallel Approaches (AILS/Casper), works with an aircraft's Traffic Alert and Collision Avoidance System, which alerts pilots if they are on a collision course with another airplane.

The AILS/Casper system also relies on a differential Global Positioning System receiver, which alerts a pilot when the airplane has veered from its planned flight paths. A data link between aircraft is needed to support the alerting function.

The NASA/Honeywell software provides an electronic equivalent to the "see and avoid" process that occurs when a pilot spots an aircraft and takes action to avoid a collision. But in poor weather conditions, pilots cannot rely on sight. With the new software, if the navigation system fails or another plane comes too close, the system will provide visual and audio warnings and offer a maneuver to solve the problem.

AILS/Casper is "not the answer for all the delays. It's the answer for some of the delay," said Brad Perry, manager of reduced spacing operations at NASA's Langley Research Center, Hampton, Va.

About 10 airports nationwide have parallel runways spaced between 2,500 feet and 4,300 feet apart , Corwin said. If the runways are separated by more than 4,300 feet, landings are not affected by instrument landing conditions, he said.

NASA and Honeywell conducted in-flight demonstrations of AILS/Casper at the Minneapolis-St. Paul airport this month to test how the alerting algorithms could work with the increased position accuracy provided by GPS and the upcoming Automatic Dependent Surveillance-Broadcast (ADS-B) system, which will enable landing aircraft to communicate with each other.

The demonstration marks the end of NASA and Honeywell's work on the project, which started in 1994. NASA has provided $2 million in project funding, and Honeywell has invested $1 million. Earlier this year, 16 airline pilots participated in a simulation of the software at Langley, and a flight test was conducted at NASA's Wallops Flight Facility.

Follow-on research could further decrease the required distance between parallel runways, Perry said.

Honeywell will no longer invest in AILS/Casper, but Corwin said he hopes a customer will be willing to install the system, which requires certification from the Federal Aviation Administration.

Northwest Airlines is interested in increasing the capacity at all three of its hub airports - in Detroit, Memphis and Minneapolis - which have closely spaced parallel approaches.

"Anything we could do to improve the throughput is of great interest to us," said Bob Buley, manager of flight technical development for Northwest.

Buley plans to encourage Northwest management to look at AILS/Casper as well as other solutions to handle capacity problems. "The hardest thing to deal with is the transition, the investment and equipage time," he said. "It won't be a choice if we're going to see maximum capacity at our hub airports."

Airlines must study how much the system would increase the number of landings during bad weather, Buley said. The current estimate is at least 12 percent.

"This thing can have a positive influence in the construction of new runways," Buley said. "This technology will allow us to buy less and occupy less real estate."