Washington-based Presidential Airways and another airline so new it has yet to carry a passenger emerged yesterday as major winners in a government-run lottery for the right to fly in and out of Washington National and two of the nation's other busiest airports.

Eastern Air Lines suffered the biggest loss, giving up 10 percent, or seven daily scheduled flights, at New York's LaGuardia Airport, one of the principal hubs in the airline's route system. Eastern also lost four landing slots at National.

The purpose of the one-time lottery, run by the Federal Aviation Administration, was to allow more carriers the use of National, LaGuardia and Chicago's O'Hare, all of which have limited landing rights -- or slots -- because they are so crowded. Five percent of all the slots at these airports were taken from carriers and offered at no cost in the lottery.

"This has produced the most significant group of new carriers at these airports in all 16 years of the high-density rule," said Edward P. Faberman, deputy chief counsel of the FAA. "This and 'buy-sell' will let an aggressive carrier go out and get into a market."

The high-density rule limits the number of flights allowed into crowded airports each hour.

The lottery comes only days before a new Transportation Department rule takes effect on April 1 permitting airlines to buy and sell their valuable landing rights at the three airports -- and New York's Kennedy -- for whatever price they can get.

Critics have said one effect of the "buy-sell" plan will be to price landing rights so high that it would effectively cut off new competition. On the other hand, established airlines have complained that the lottery deprives them of the right to use airports in which they have invested millions of dollars.

Although many large airlines lost slots at all three airports, only Eastern at LaGuardia lost as much as 10 percent, the maximum loss allowed any one carrier under the lottery rules.

New York Air, whose parent company, Texas Air Corp., is seeking to take over Eastern, lost five slots at National, while one of its newest competitors, Presidential, based at Washington Dulles International Airport, won four slots at National and seven at LaGuardia yesterday. Presidential, which has no service at either airport, welcomed the windfall.

"Presidential wants to make the Northeast Corridor more competitive than it now is," said Alan R. Youngberg, Presidential's vice president in charge of sales. "Although we would like a greater presense at both airports, this will get us in a door that has been slammed shut."

"Before this auction, there was no way an airline like Presidential was going to get into a National or LaGuardia," said Faberman.

Without question, the luckiest company at yesterday's lottery was McClain Airlines, which has not yet even begun to fly.

After going to federal court in San Francisco to get into the lottery, McClain was added to the roster at the last minute yesterday morning and promptly won eight slots at O'Hare. The Phoenix-based carrier expects to begin flying between Chicago and Los Angeles, Phoenix and Dallas within four months.

Without any other hope of making it into intensely overused O'Hare, McClain pulled first pick yesterday morning. "This could be worth millions to us," said Hank Ward, McClains' vice president and comptroller. "This is a very lucky day for this airline."