Eleventh-hour negotiations among the 19 airlines that serve National Airport yesterday failed to break a deadlock over distribution of the airport's flight quotas in September, raising the strong likelihood that the question will be settled by the Federal Aviation Administration.

Airline officials said agreement was being blocked by Ozark Air Lines, which is holding out for a bigger share of the airport's 555 daily "slots"--rights for take-offs or landings. All other airlines have agreed to accept the number of slots they currently hold.

Unless Ozark or another carrier reduces its request by 11 a.m. today, the committee of airlines that allocates slots will turn the question over to the FAA, a committee spokesman said yesterday.

Industry analysts believe that imposition of a solution by the FAA--likely to be an extension of the current allocation--could raise pressure for finding a new way of governing access to the federally owned airport, possibly a "buy-sell" arrangement in which the currently free slots would be sold to the highest bidder.

Such a system could raise fares and alter the mix of services offered at National. It could also create a precedent for similar systems at airports around the country, analysts believe, and for that reason it is being watched closely by the industry.

A meeting of the airline scheduling committee at the Sheraton National Hotel in Arlington yesterday morning focused on how the slots should be divided next month. The St. Louis-based Ozark currently has six slots, but is holding out for eight beginning Thursday.

Ozark spokesman Charles Ehlert said he did not know what happened at yesterday's meeting, but said that Ozark long has wanted to increase its service at National.

Many carriers share this objective, but getting the added slots has become increasingly difficult in recent years. The FAA has reduced the number of slots in an effort to control congestion and noise, and competition for the remaining ones has increased as new airlines have been created in response to deregulation of the industry in 1978.

In addition to the 19 carriers now at National, several others, including Air Atlanta, Air America, and Braniff (provided that a rescue plan is worked out for the bankrupt airline), are seeking rights to operate there.

With the committee experiencing growing troubles in deciding who should get slots, some carriers, including Eastern Airlines and New York Air, have argued for a buy-sell arrangement to end the deadlocks and give slots to those willing to pay the most.

With the estimated value of slots said to be about $250,000 each, opponents have said such a system would penalize smaller carriers and might spread to other airports, placing a new financial burden on an industry that is still reeling from the effects of the recession.