FAA refines guidance system

The Federal Aviation Administration will provide technology next year that will guide pilots much closer to the runway during landings in poor visibility.

In December 2003, the FAA had planned to offer guidance down to 350 feet to planes equipped for the Wide Area Augmentation System (WAAS), a network of ground stations that correct satellite signals and broadcast them to receivers on aircraft.

Raytheon Co. is set to deliver the system at that time, but with an enhancement that will enable pilots to descend to an altitude of 250 feet. The FAA had not expected to offer that level of precision approach until 2005.

FAA enhanced WAAS' capability using a mathematical formula, recently developed by Mitre Corp., to create a new landing procedure that put WAAS two years ahead of schedule.

WAAS improves information supplied by the Defense Department's Global Positioning System, which lets airborne, land and sea users determine their positions anywhere in the world.

Unlike most commercial jets, which have instrument-landing systems, many smaller aircraft come unequipped for dealing with landing in bad weather. WAAS aims to guide pilots of such aircraft close enough to the ground — even in zero-visibility conditions — to see the airport and continue descending.

To use the system, special equipment, estimated at $5,000 to $10,000 per plane, will be needed.

"The advantage is safety," said Tammy Jones, a spokeswoman for FAA. "As you lower the minimums, we're getting an even clearer view."