operations from Bermuda, a Harbour Radio spokesman said yesterday.

"It would be a great blow indeed,'' the spokesman said. "It would severely devastate our capability.'' With no USNAS, there would be no HH1N Huey search and rescue helicopters and no P3-Orion search plane to help in search and rescues. The two helicopters and one aircraft now operate from the St. David's base. Communications would also be impaired.

And the US Coast Guard, which now sends C-130 aircraft to Bermuda to assist with search and rescues, could also be affected.

There has been no official word that the USNAS will close. But US Joint Chiefs of Staff chairman Gen. Colin Powell said last week there was no legitimate military reason for the base's continued existence, and there were no guarantees it would stay open.

Premier the Hon. Sir John Swan has said Bermuda will try to negotiate arrangements for the orderly transfer of vital operations in the event the base closes.

A recent US Defense Department report on the USNAS estimated search and rescue operations cost $687,000 in 1991. In 1992, 73 flight hours with US Navy aircraft were spent on search and rescue, as well as 151 hours with US Coast Guard aircraft, the report said.

Lieut. Tracy Emerson, a helicopter pilot and assistant operations officer at the base, said its search and rescue capabilities were primarily intended for military searches, but those have arisen very rarely. So the Base has mostly responded to civilian calls, like the recent loss of the pleasure craft Simply Red .

In the event of a Base closure, "I don't know if the US would keep a presence here just for search and rescue -- I would doubt it,'' Lieut. Emerson said.

"It would be expensive. I don't think you could justify the cost.'' Last year, the USNAS was involved in about 20 search and rescues from Bermuda, and about 12 personnel are assigned to that work, he said. All have received special traning in search and rescue.

The US Coast Guard, which sends C-130 aircraft for more extensive searches, would likely see its costs increase if the base was to close, he added. "When they come here they pretty much stay and use the naval facility,'' Lieut.

Emerson said. Also, "they get navy fuel, which is cheaper.'' A US Coast Guard spokesman could not be reached for comment yesterday. Under the terms of its lease, the US Navy would have to give at least one year's notice before pulling out of the Base.