Washington ? Foreign-owned airlines, noting that many countries don’t allow handguns, criticized a U.S. plan to let commercial airline pilots carry weapons in the cockpit.

The Senate voted overwhelmingly Thursday to arm pilots after the Bush administration dropped its opposition. The House voted 310-113 in July for a similar plan.

The two versions must be reconciled, and difficult issues remain about how to implement the program in countries that don’t allow handguns to be carried. Sen. Ernest Hollings, D-S.C., chairman of the Senate Commerce and Transportation Committee, noted that El Al pilots aren’t armed, although the Israeli airline is renowned for tough security.

The International Air Transport Assn., which represents U.S. and foreign-owned airlines, opposes arming flight crews with lethal weapons.

“What’s going to happen when you land in a country that doesn’t allow guns?” asked Wanda Warner, the association’s spokeswoman. “How is this going to work when American Airlines lands in London or United lands in Rome?”

The heads of 21 major U.S. airlines signed a letter to the Senate opposing the measure because of the possibility that a gun might be fired accidentally in a pressurized cabin or misplaced. Pilots’ unions strongly advocate carrying guns as a last line of defense against terrorists.

Pilots and aviation officials in Sweden, Norway and Denmark dismissed the idea, saying suspected terrorists should be stopped before they get on the plane.

“In this case, the Americans are a little out of step with the rest of the world,” said Jan Deiset, deputy leader of the Norwegian Pilot’s Union.

The criticisms echo the Bush administration’s worries about compliance with gun-control laws overseas, expressed in a letter sent Thursday to Sens. Hollings and John McCain, R-Ariz., the Commerce and Transportation committee’s ranking Republican.

“There are numerous thorny issues that must be resolved with foreign nations and foreign airlines,” said the letter, written by Transportation Security Administration chief James Loy.

“Would we authorize the employees of foreign air carriers to participate in this program?” Loy wrote. “What type of background investigation would be possible and necessary? Who would pay?”