Washington ? After more than a year of debate amid fierce opposition from the airline industry, Congress is poised to give thousands of commercial pilots the right to carry guns in the cockpit.

A bill expected to clear Congress this week will enable airline pilots to voluntarily carry pistols on the flight deck after undergoing a training course tailored by the FBI. More than half of the nation’s 80,000 to 100,000 passenger airline pilots may eventually participate, according to experts.

The 484-page bill, which creates the Homeland Security Department, could pass the Senate as early as today to advance to the White House for President Bush’s signature. The provision arming pilots would be phased in over three months.

Passage of the measure gives a hard-won victory to organized pilots, who clamored for the legislation after the terrorist hijackings on Sept. 11, 2001. Participating pilots will be deputized as unsalaried federal officers with perhaps the smallest jurisdiction on the planet – the narrow confines of their cockpits.

The armed pilots, who will be called federal flight deck officers, will be authorized under the new law to defend the cockpit “against acts of criminal violence or air piracy.” They will be prohibited from taking the guns outside the cabin, even to face down terrorists threatening to kill hostage passengers.

The thrust of the law is to enable pilots to remain in control of the cockpit and land their planes as quickly as possible if hijackers take control of the passenger section. The government has ordered that all cockpits be fitted with bulletproof doors by 2003.

“It’s not strapping a weapon to your thigh and boarding a plane,” said Rep. John Mica, R-Fla., the House aviation subcommittee chairman. “It’s going to be very closely monitored.”

Although full details must be worked out by a federal regulatory agency, preliminary proposals envision pilots wearing tear-away chest pouches that would hold FBI-approved pistols.

Phillip Beall, a 39-year-old American Airlines captain, is a reserve law enforcement officer in Dallas County and practices with a .40-caliber Glock pistol on his ranch near McKinney. He was active in leading the fight for arming pilots and is eager to apply under the new law.

“I personally believe if we had had this program in place on Sept. 11, 2001, we would have had a dramatically different outcome,” Beall said Sunday.