In the control tower at Robins Air Force Base, Ga., Master Sgt. George Green asks one important question when the pilot of a fighter, attack or bomber aircraft requests permission to make an unscheduled landing.
“Are you carrying external electro-explosive devices?”
If the answer is yes, chief controller Green picks up a direct line to the operator of the PAVE PAWS radar installation two miles south of the central Georgia base.
The radar operator flips a switch, and for several minutes, until the plane lands, half of the $90 million radar screen, built to give instantaneous warning of any submarine-launched missile off the southeastern United States, is shut down.
Since November, 1987, the Air Force now acknowledges, the north face of PAVE PAWS at Robins has been turned off an average of 14 times a month--for a total down time of about an hour a month--so that planes carrying externally mounted EEDs can land.
Operation of the defensive warning system is interrupted to prevent accidental detonations of the EEDs, tiny explosive charges that are in virtually every military weapons system and in the planes and ships that deliver them.
EEDs are used, among other things, to trigger weapons, drop bombs, or jettison fuel tanks. They are detonated by an electrical circuit, but can be set off by high levels of electromagnetic energy from environmental sources such as radio waves, radar, static electricity and lightning.
The Air Force insists that the periodic interruptions have not hindered the effectiveness of the early warning system because the shutdowns occur at random and other radars are available as backups. Routine maintenance, the Air Force says, shuts the radar down for about 40 hours a month.
“Our primary concern at Robins with PAVE PAWS is safety of flight,” Lt. Col. John Harmon, commander of the base communications squadron, said. “We want to make sure that we have procedures in effect so there is no possibility of any plane having externally mounted EEDs flying in a dangerous situation.”
Protects Wide Area
PAVE PAWS stands for Precision Acquisition Vehicle Entry Phased Array Warning System. The 10-story, pyramid-shaped installation at Robins, one of four such facilities in the nation, has thousands of computer-directed antennas that can scan 240 degrees to a distance of 3,000 miles. The radar reportedly can identify an object the size of a basketball when it is 1,500 miles away.
The radar near Robins is the only one near an active runway; there have been no problems reported near the others.
PAVE PAWS had been in operation for a year at Robins before Air Force officials became convinced that its powerful electromagnetic emissions might endanger aircraft.
They instituted the periodic shutdown procedure and established a restricted zone around the radar of one nautical mile, about 6,000 feet, for all aircraft flying at or below 6,400 feet.
The Air Force contends that it has taken a conservative and cautious approach at Robins, but critics, such as Patricia Axelrod, coordinator of the HERO Project, say the location of the radar near a base where ordnance is handled is a disaster waiting to happen. The air base, Georgia’s largest, is near the community of Warner-Robins, population 40,000.
Federal Suit Filed
The HERO Project, which derives its name from the Navy acronym Hazard of Electromagnetic Radiation to Ordnance, is part of a coalition that has filed suit in federal court in Washington, alleging that the military has not shielded its weaponry sufficiently to prevent accidents.
Axelrod and the defense specialists assisting her in the lawsuit say that the 6,000-foot hazard zone is not sufficient. She cited Navy documents recommending that the EA-6 Prowler airplane, laden with electronic-warfare equipment far less powerful than PAVE PAWS, should be kept at least 8,000 feet away from areas where ordnance is handled.
Axelrod also said the flight restrictions at Robins force pilots into “a trapeze act without a net” because of the possibility of human error in the chain of communication required to shut down the radar when a plane is landing.
Sen. Sam Nunn (D-Ga.), chairman of the Senate Armed Services Committee, also has criticized the restrictions because of their reliance “on the potentially fallible human links between the pilot, control tower, and PAVE PAWS radar operators.”
Nunn has asked the Air Force for an official evaluation of the potential hazards to aircraft at Robins, and of the long-term adequacy of the current procedures.
Lt. Gen. Donald J. Kutyna, who heads the Air Force Space Command responsible for the warning system, acknowledged in a recent interview that he would rather have the radar someplace else.
“Based on what I know today, the radar may not hurt anything, but there is some concern. Otherwise, there wouldn’t be any flight restrictions,” he said. “If I had the choice, all things being equal, I would put the radar where I would not have to impose any safety zone.”
The Air Force said the initial environmental assessment for PAVE PAWS concluded that the restricted zone needed around the radar would not interfere with the flight paths of any aircraft using the Robins runway.
That conclusion was changed in 1987. Further calculations were made while the Air Force was developing plans to triple the power of PAVE PAWS to enhance its ability to track satellites in space. The new figures indicated that a larger restricted zone was needed.
Peak Power Measured
The key difference in the new calculation was the way the radar’s power was measured. The first assessment used the average power of the radar pulses over time; the later one used the peak power of each pulse.
Air Force officials acknowledge that the contractor who did the initial assessment recommended using peak power to calculate the restricted zone, but that advice was rejected because Air Force experts at the time did not believe brief exposure of an EED to the radar pulses would be hazardous.
“We were on the cutting edge of technology with PAVE PAWS at the time we made that initial environmental assessment,” Kutyna said. “To have learned something new since that time does not say that you were making a mistake before.”
The Air Force already has spent $600,000 to have Raytheon Corp., which built the radar system, study the problem. Raytheon recommended moving the installation, at a cost of $37.7 million, or modifying it, at a cost of $27 million, so it would shut down automatically if a plane breached the restricted zone.
Permanent Solution Sought
Kutyna said moving the radar is not feasible, but the modification proposal is under consideration. He said a panel of senior Air Force officers has been convened to make recommendations by June on a permanent solution to end the flight restrictions.
In the meantime, the Air Force has shelved its plan to triple the radar’s power so it could take over the space-tracking functions of the outdated radar system at Eglin Air Force Base, Fla., at an annual savings of $11 million.
“Unless there is a solution in the books that comes out of this study, I would say the chances of putting that (power) upgrade on there at this time are not high,” Kutyna said.