WASHINGTON -- Defense Secretary William J. Perry approved yesterday the use of a radar jammer, made in Maryland and previously rejected as flawed by the Pentagon, to help protect Marine fighter pilots patrolling the "no-fly" zone over Bosnia.
Mr. Perry ordered the jammers, refined since they failed the Pentagon's in-flight tests three years ago, to be immediately installed in the 12 Marine FA-18Ds, which fly daily NATO missions over Bosnia from Aviano, Italy.
His decision came five weeks after an Air Force pilot, Capt. Scott F. O'Grady, was shot down by a SA-6 missile over Bosnia. That incident highlighted the danger of allied air missions flown across terrain held by Serb separatists.
The first 12 of 24 ordered jammers left the Marine air base in Beaufort, S.C., early yesterday, hours before Mr. Perry authorized their installation. The rest of the jammers are to be flown out today, and the devices could be in use as early as tomorrow.
The speed of the shipments reflects the Marines' eagerness to acquire the protection that the jammers offer against the ground-to-air SA-6 missiles operated by the Bosnian Serbs. The Marine planes now use a different jammer, which Marine pilots think is less effective.
To reduce their vulnerability, the Marine pilots requested the release of the stored jammers -- made by Linthicum-based Westinghouse Electronic Systems Group and ITT Defense, of Nutley, N.J. The system is officially called the Airborne Self-Protection Jammer (ASPJ).
The Navy tested the jammer on an F-18D to assess its effectiveness against SA-6 attacks. The tests showed that the jammer, which sends out electronic signals to confuse a missile's radar targeting system, was particularly effective in foiling the SA-6.
"The machine they are deploying over Bosnia is not the same machine that ran into all the problems and was shelved in 1992," said Kenneth Bacon, the Pentagon spokesman, explaining that the system's computer software had been improved.
The deployment does not mean any immediate new work for Westinghouse, which is now producing the jammers for the air forces of Finland and Switzerland. The Pentagon has 102 of the units in storage.
Mr. Perry said the deployment was "a temporary modification based upon the current threat in Bosnia." He added: "This approval should not be interpreted as an approval of [the Westinghouse jammer] as a long-term solution without further formal review."
But if the system proves effective under battlefield conditions, it could persuade the Pentagon to consider wider deployment. Mr. Bacon, the Pentagon spokesman, cautioned that it was "premature" to consider wider application of the jammer throughout the services. Initially, the Navy and Air Force considered buying 2,200 of the jammers, at a total cost of $9 billion.
"This is a very limited action," Mr. Bacon stressed, noting that the jammers would be deployed on only 12 Marine planes operating over Bosnia. The system, he said, will be subjected to "further evaluation." The Navy is already testing the jammer for its carrier-based F-14Ds.
Maryland's two Democratic senators, Paul S. Sarbanes and Sen. Barbara A. Mikulski, had argued that the original cancellation of the $2 billion program, at a cost of 450 Westinghouse jobs, was based on faulty test criteria.
They welcomed the announcement of the deployment yesterday.
"U.S. pilots in the air over Bosnia deserve every protection American technology can provide," Mr. Sarbanes said.
"Installation of the ASPJ on our aircraft is obviously something our armed forces want and need, and it is very reassuring to know they will now get it."