Northwest Airlines asked a federal appeals court yesterday to prohibit the Department of Transportation from implementing its plan for allocating access Washington's National Airport after Dec. 1.

In a suit filed in the U.S. Court of Appeals in St. Louis, Northwest urged that the DOT be required to maintain the allocations that are in effect for November, an action which would bar the new low-fare service between Washington and New York that New York Air plans to begin on Dec. 14, as well as expanded services by other airlines new to National Airport.

"Absent a stay, much of the airline industry and the public it serves will be severely disrupted during one of the busiest travel times of the year," Northwest contended in its suit. "Carriers will be forced to change drastically schedules they already have in place and in many cases have been operating for years, on extremely short notice."

Northwest is one of a dozen airlines with the most flights at National that were forced either to give up some slots altogether or to move one flight a day to 10 p.m. under the DOT plan to make way for new services by others.Northwest was forced to move a flight to 10 p.m., an action its suit claims will cause it to cancel or reschedule eight flights at National.

In its suit, Northwest argued that the DOT's plan was arbitrary and capricious, that the agency did not follow proper administrative procedures and that it lacks the legal authority to distribute slots at National.

The DOT had been asked by the airlines themselves on Oct. 14 to come up with a plan for allocating National's limited slots -- the industry term for takeoffs and landings -- when the 23 airlines seeking operations there had failed to come up with their own formula for allocating flying hours for the period between Dec. 1 and April 26. The airlines had been able to work out a formula for the month of November largely because New York Air wanted to begin its services in December and agreed to let the committee settle the month of November without participating.

No offical comment on the suit was available yesterday from DOT.