Discussions among airline representatives on the possbility of shifting some flights from National Airport to the area's other two airports, originally set for tomorrow, have been postponed until March 2.

Officials of the Department of Transportation, which is organizing the meeting, said the delay would give the airlines and other parties, including promoters of Dulles International Airport, additional time to prepare for the meeting.

Members of the Dulles Policy Task Force, representing Virginia state and local bodies and chambers of commerce, are hoping to use the time to convince airlines that they can fill planes with passengers and make money by transferring some flights from National to underutilized Dulles.

It was the task force that originally instigated the current set of meetings by asking the Civil Aeronautics Board to grant the airlines antitrust immunity to engage in discussions on shifting flights. The authority was granted when four airlines operating at National filed a petition asking for the talks.

Late last week, the task force mailed to all the airlines operating at National a 50-page brochure and study that tries to make a case for transferring some service to Dulles. "The book is aimed at airline planners not familiar with the Washington area," task force member Leo J. Schefer, a vice president of British Aerospace Inc., said. "Our contention is there would be more passengers at Dulles if there was more service there."

The study, prepared by Simat, Helliesen & Eichner, a transportation consulting firm, outlines the area's demographics and economics and the facilities at Dulles. It also concludes that passengers in the Dulles service area--a geographic area for which Dulles is considered more convienient than National--could support easily the transfer of 25 percent of the flights to major cities from National to Dulles.

The report also suggests that flights into National with a high percentage of through passengers going on to another city could be moved to Dulles, since those passengers don't care where the stop is made.

Airline officials in the past generally have suggested that they didn't want to move flights to Dulles if their competitors stayed at National. At a meeting late last month to work out ground rules for the next meeting, many said if the airlines are going to agree to shift some service out of National, they will have to shift all flights to some destinations. No airline official voiced support for shifting a percentage of a market to Dulles or BWI.