As any frequent flyer knows, bad weather can make for interminable airport delays. One reason is that the Federal Aviation Administration requires airports with parallel runways less than 4,300 feet apart to stagger incoming flights or close one of the runways during foul weather. Now, a new type of radar system called Precision Runway Monitors (PRM) could lessen the delays.
The FAA recently awarded a $33.7 million contract to Allied-Signal Inc. for a PRM system that updates air traffic controllers on the position of approaching planes twice each second vs. once every five seconds for conventional radar. The close monitoring will enable airports to operate parallel runways even in bad weather.
The system projects the plane's path and issues warnings if it begins to stray toward the safety zone between runways. On the controller's screen, the plane's symbol changes from green to yellow if the aircraft is within 10 seconds of crossing the line. It flashes to red and an alarm sounds if the plane actually enters the zone--giving the controller enough time to order evasive action. The new PRMs will be installed in the Atlanta, Minneapolis-St. Paul, Memphis, Raleigh-Durham, and Baltimore-Washington International airports beginning in 1994.