US regulators proposed a USD$500,000 fine against Alaska Airlines on Friday for allegedly operating a passenger jet on 478 flights without proper lighting to identify emergency exits.

The Federal Aviation Administration said that Goodrich Aviation Technical Services, an outside maintenance provider for the Seattle-based carrier, failed to reinstall the lighting after performing extensive work on the Boeing 737 in 2004.

Dozens of subsequent inspections did not detect the problem, the FAA said.

Federal regulations prohibit an aircraft from carrying passengers unless lights identifying emergency exits are working.

Alaska discovered the problem and installed the required lighting months later, on February 2, 2005. However, an FAA inspector said on February 10 that the wrong lights had been installed. Alaska operated the aircraft for nearly a week before changing the lights, FAA said.

Amanda Tobin, an Alaska spokeswoman, said the airline was aware of the proposed fine and the two sides continue to discuss the matter. "The final resolution and amount of the civil penalty is yet to be determined," Tobin said.

Airlines are often able to negotiate a reduction in proposed fines.

Separately, Alaska's ramp and baggage handling service provider, Menzies Aviation, is launching a safety review of ramp operations after another incident involving a jet at Seattle-Tacoma Airport, Alaska said.

The airline also stepped up its oversight of Menzies on Friday after a 737 that was being moved a matter of feet by a push-tug inadvertently struck a jetway and a baggage handling machine on Thursday night. The incident resulted in minor damage to the aircraft, Tobin said.

On December 26 at Sea-Tac, a baggage handler operating a belt loader apparently struck an Alaska MD-83, which lost cabin pressure shortly after takeoff. Federal safety investigators said they found a 12-inch gash near the forward cargo door after the plane landed safely. The investigation is ongoing.

Menzies Aviation is a unit of British-based John Menzies, a global logistics group.