LESS THAN 18 months ago, a jet airliner and a small airplane collided over San Diego and 144 persons died. Within the last two months, four other airliners have had near-misses with small planes -- one of them a Marine Corps helicopter -- in the same area. Isn't that enough?

The National Safety Transportation Board is right in saying (as it has done twice in the past three weeks) that something has to be done quickly about the air traffic safety rules around San Diego. It shouldn't take a fifth near-miss, or a second fatal collision, to get those rules changed. But the board is wrong in pointing at the Federal Aviation Administration as the villain.

Because it attempted to follow up quickly on the original recommendations made by the Safety Board after the San Diego crash, the FAA took a bad beating on Capitol Hill last summer. It was told to slow down the pace at which it was putting those recommendations into practice and to forget completely about tightening up the rules under which airplanes sometimes fly without much guidance fromair traffic controllers. In fact, members of the House bragged on the floor about threatening to cut the FAA's appropriations unless Administrator Langhorne Bond accepted their view of air safety.

The truth is that general aviation -- the people who own and fly the non-commercial planes -- has more poltical clout than the citizens who fly on the big airliners. General aviation turns out in force every time anyone -- the FAA, a member of Congress or a newspaper -- suggests that the safety of airline passengers should be given precedence over the convenience of private pilots. That force, which can be turned into votes, is enough to keep anything significant from happening.

So if the Safety Board wants to complain again -- as well it should -- after the fifth or sixth near-miss is San Diego (or the second fatal collision), it ought to get its target right. The owners of 98.7 percent of the registered aircraft (to use the number supplied by Rep. William H. Harsha during the House debate) don't want "unreasonable" restrictions, as they call them, that increase the area in which they can fly only under control from the ground. What the hundreds of thousands of passengers who fly on the other 1.3 percent of the aircraft may want is, of course, irrelevant.