The Bush administration is ready to allow some US airline pilots to carry guns in the cockpit on a trial basis, a senior government source said.
Details of the plan are still being worked out by the Transportation Security Administration (TSA) and other officials, but the basic framework for a limited test program has been drawn up.
A spokesman for the TSA, which handles aviation security, refused comment on the matter.
No date has been set for an announcement on the administration's new policy, although momentum is building in Congress to pass a plan to arm pilots as a final defence against potential hijackers.
The House of Representatives approved legislation in July that would, on a voluntary basis, arm all 70,000 commercial pilots in the United States. A similar proposal yet to be considered in the Senate would also give flight attendants self-defence training.
Transportation Secretary Mr Norman Mineta personally opposes arming pilots and told Congress this spring it would not happen. He said stronger cockpit doors and armed air marshals on flights, would protect the aircraft and passengers.
But pressure from lawmakers and unions representing commercial pilots as well as a leadership shake-up at the TSA prompted Mr Mineta to reassess the issue this summer.