When there's only so much traffic allowed at an airport -- and Washington National is a prime example -- what's the best way to allocate and transfer landing and takeoff rights? And if these privileges already belong to certain airlines, how do you open up a finite number of landing and takeoff rights, known as "slots," to more competition? Transportation Secretary Elizabeth Dole is proposing that airlines be permitted to buy and sell their slots at National and three other airports for whatever price they can get. That's not as unfair as it may seem at first glance -- but it could be even better with modifications.

Right now the slots at National, Chicago's O'Hare and New York's Kennedy and aGuardia airports belong to those airlines that got them under government regulations and cozy arrangements worked out between themselves. Then along came deregulation, and small airlines began demanding a share of the action that the bigger lines weren't at all eager to share. If nothing is done, nothing is likely to inspire sudden generosity -- and therein lies the basis for the Transportation Department's efforts to establish a fair system without going back to cumbersome regulation. Under the new "buy-sell" proposal, which is geared to take effect April 1 unless Congress does something else, the airlines that have the slots now would continue to hold nearly all of what they have. Other slots would continue to be protected for commuter airlines and special flights. Five percent of existing slots -- those currently held but not used and, if necessary, some to be withdrawn to reach that figure -- would be made available by lottery, with preference to carriers not using the airport.

An excluded airline could gain access by paying the slot-holder whatever price that carrier demanded. But why should these slot-holders get such a windfall profit for rights they got for free? They point out that they have made huge investments in airport facilities, services and improvements for these landings and takeoffs.

But there's something wrong with letting these airlines clean up too handily for privileges they never had to purchase, that in fact were allocated by the government. Why not 1) increase the 5 percent of existing slots to be made available by lottery to, say, 10 or 15 percent, and 2) put a windfall tax on profits made from the sales of any other slots? The free market would still be allowed to work -- and the government could reap some benefits as well.