The federal government's plan to allow commercial airline pilots to carry guns will begin cautiously, with just 50 pilots in the initial program, the Transportation Security Administration said yesterday.

The TSA, which was directed by Congress last year to develop a training program by Feb. 25 for pilots to carry guns, has yet to finalize decisions about other details of the program, such as the exact date training will begin, how guns will be transported to airplanes and how pilots will interact with federal air marshals.

The agency plans spend $500,000 for an initial program that is scheduled to start in the next several months. The test phase with the 50 pilots will last several weeks before the agency launches a full-scale program, said Robert Johnson, a TSA spokesman. Tens of thousands of pilots are expected to eventually participate.

"It's prudent to test the curriculum on a smaller group than to begin a full-scale implementation right from the beginning," Johnson said. "It's just to make sure you've covered all of the bases in development of the program and make sure there's not anything missing that would be important for a successful training experience."

Pilots lobbied aggressively after the Sept. 11, 2001, terrorist hijackings to be allowed to carry guns, an idea that the TSA rejected as a safety risk because the guns could be lost, stolen or used against passengers and flight crews. But Congress, unhappy with improvements made to airport security by the anniversary of the attacks, voted overwhelmingly last fall to allow all pilots who volunteer to carry guns. Lawmakers also directed the TSA to develop the training program.

Pilots will be trained at Federal Law Enforcement Training Centers in Glynco, Ga., and Artesia, N.M., where federal agents such as those from the Federal Bureau of Investigation, U.S. Customs Service, Federal Air Marshal Service and the U.S. Border Patrol also train. Pilots who undergo the training will be called "federal flight deck officers" and must complete recurrent training.

Johnson said the agency is considering one week of training for pilots, but a final decision hadn't been made. He said he did not know when the training would begin. The TSA must coordinate with the training centers and with volunteer pilots before announcing the start date, he said.

The size of the full-scale program "will all hinge on funding," Johnson said.

The TSA did not specify an amount for the program in its 2003 budget request to Congress.

The agency estimated last fall that it would cost $900 million to arm pilots, but pilots' groups estimate the cost at $160 million to $170 million. Both sides agree that the figure depends on how many pilots participate.

Al Aitken, a spokesman for the Allied Pilots Association, a union representing American Airlines pilots, said he was pleased the agency has included pilots' groups in the development of the program.

"They are dealing directly with us so we are having the opportunity to shape their thoughts on this," Aitken said. "We are having some success."