Every day at National Airport 20,000 automobiles, 5,000 taxicabs and 160 Metrobuses compete furiously to get 15,300 air travelers on and off 650 flights and 8,500 airport employees to and from work.

There are no winners in the resulting traffic chaos and as somebody once said, only survivors. But, rest assured, the government is bringing change.

By late March, if weather permits completion, National Airport will present its already befuddled customers with a new, one-way street plan and spiffy color-coded signs to explain it.

Then, in July, a Metro train will pull into the airport station for the first time. To travel the last one-third mile from the Metro to the airport, a traveler will have to wait five minutes for the next shuttle bus or dart across two lanes of traffic then expected to be speeding efficiently because of the new, one-way road system.

"It's going to be another black eye and we're going to get the blame," moaned Metro General Manager Theodore Lutz. "This is not our fault."

The problem of how to get from Metro to the airport and why it isn't solved is just a part of the National Airport story. Wrapped up with the uncertainty on that small point is indecision on the future of the airport itself and involves such questions as these:

Are a substantial number of flights ever going to be transferred from National to Dulles International?

Should National permit the newer, quieter jumbo jets to land there, perhaps in exchange for a reduced number of flights?

Should terminal facilities, particularly in the strained North Terminal, be expanded?

The fact those questions exist, however, will be of little solace to the plane-bound traveler who rides the subway from downtown to the airport in a record 10 minutes, then takes another 10 minutes in a hazardous jour- ney from the Metro to the ticket counter.

Metro has been on its way to National for a long time. Money to ($2 million) build a connector to the airport has been in the federal budget for two years. Not one contract has been awarded. National Airport officials are just now in the final stages of choosing a firm to do engineering and design work for the connector. Why?

"There oughtn't to be much of a mystery about that," said James A. Wilding, deputy director of Metropolitan Washington Airports. "I think the uncertainty as to whether there should be a new North terminal and if so how big it should be relates back to the uncertainty . . . in the Washington area on the proper role for National Airport."

Metropolitan Washington Airports is an arm of the Federal Aviation Administration and owns and operates National and Dulles International. Those are the only airports in the country owned and operated by the FAA.

An expanded North Terminal would probably spill into Parking Lot No. 1, Wilding said, and would be much closer to Metro. Engineers will have the problem, he said, of designing a pedestrian walkway to "hit a moving target." Some sort of motorized "people mover" or moving sidewalk is planned.

In the two years that it takes to design and build, WIlding said, he hoped people would ride a shuttle bus between the Metro and the airport terminals. A bus will run every five minutes.

"Doubtless there will be some folks who will set out for the North Terminal if the bus isn't right there," Wilding said, "But we'd frankly rather discourage them from trying to walk."

There is good news. As part of the one-way road system the FAA is installing at National for $1 million, a three-bay bus dock is being constructed under the Metro rail terminal. It will be completed in plenty of time for the Metro opening, Wilding said.

Metro is planning to terminate the routes of many Washington-bound buses at the National Airport rail terminal. Those buses serve Alexandria and the Fairfax County area south of Alexandria to Mount Vernon. A few buses will continue beyond the airport into Washington.

Metro, the FAA and the Metropolitan Washington Council of Governments (COG) are also studying a plan to run nonstop rush hour buses between National Airport and the site of the future Huntington Metro station, in Fairfax County not far from the Penn Daw shopping center.

If that plan is adopted, about 500 parking places will be opened at Huntington, where commuters can catch express service to the airport Metro rail station. "We think that plan has a lot of promise," said COG transportation planner Ronald Sarros.

But those commuters who try to use National Airport itself as a parking lot while they catch the train will not be welcome, Wilding said.

"We're optimistic," he said, "that through controlling" the cost of parking in the lots the airport can discourage commuters.

Nobody knows whether the Metro will reduce vehicular traffic at the airport. Metro's long-term forecasts - those that predict ridership on a completed 100-mile system - say that 27,000 people a day will get on and off at National. But when Metro opens its rail line there in July, National will be the southern terminus of the Metro system and only 24 of an eventual 86 stations will be opened.

Public transit brings less than 1 per cent of the airline customers to National Airport today, although about 600 of the 8,500 people who work at the airport get there by bus.

For those who continue to drive to National, there is hope for improvement. The one-way traffic plan, designed by the Federal Highway Administration, should cut down substantially on the frustrations of driving at the airport - after people get used to it.

One thing that traffic engineers regard as immutable is that automobile drivers, when confronted with something new, will do it wrong, no matter how good the sign or how adequate the advance warning.

It would be hard to imagine a more outrageous bottleneck than the one National Airport can become - particularly on Sunday at 7 p.m. Drivers curse, horns honk, buses cut people off and taxis jockey out of their assigned area onto the main roadway. Nobody goes very far very fast.

The new road system is designed to alleviate that. Now, when you come down the George Washington Parkway to the airport from Washington, as two out of three airport-bound people do, you fight your way into the ple do, you fight your way into the main terminal and cut across oncoming traffic to get in the traffic circle.

With the new system, drivers will be routed west of the terminal, then brought back in to the circle from the south, merging with traffic from Alexandria and Arlington.

Those who need the main terminal (American, TWA, Eastern, Alleghency, Northwest, United) will follow signs coded in red to the old traffic circle. Those who need the north terminal (National Delta Braniff, Piedmont) will follow signs coded in blue to that terminal, and will never enter the traffic circle.

Buses will be routed out of the mainstream of traffic and into their own docks under the Metro station. Taxis will be assigned to a specific area and their movements controlled.

All questions about why things like this were not done sooner are answered by FAA officials with the explanation that the future of National Airport has long been in doubt and they did not want to waste money.

However, airport officials are nearing completion of their first policy statement and master plan. It will follow a document published by COG in 1975, which concluded that National would have to play a major role in commercial aviation or new facilities would have to be found.

That study also suggested that if jumbo jets were permitted at National, projected passenger growth could be handled with a reduction in flights (and noise). Three-engine jumbos - the McDonnell Douglas DC-10 and the Lockheed L-1011 - carry more than twice as many people as the ubiquitous Boeing 727.

COG suggested that one jumbo could replace two regular craft in the quota system that restricts National to an average of 60 flights an hour - 40 of them by scheduled air lines.

Airline industry and FAA officials say, however, that such a plan would severely restrict scheduling flexibility and "stifle" National Airport, as Wilding said. The New York-Washington run might easily support a jumbo flight, but the Half-empty small plane to Charleston, W. Va., might get cut.

Nobody in the FAA wants to tackle a powerful congressman's direct flight from National to his state capital.

Wilding said that if the quota changes, "it will change downward," but he does not foresee it happening one a one-for-two basis.

Because of newer jet engine technology, the jumbo is quieter than most of the 727s and McDonell Douglas DC-9s flying today. "We'd like to find some way to get it in here and take advantage of the environmental plus," Wilding said. But National Airport today does not have the terminal and baggage-handling facilties necessary to cope with one airplane disgorging 325 people at the same time.