Flight cancellations stranded thousands of Christmas weekend airline passengers in the United States again on Sunday as two airlines wrestled with computer and staffing headaches.

Financially troubled US Airways scratched 29 flights systemwide after a continued "unusually high level of sick calls" from baggage handlers and flight attendants, said Amy Kudwa, a spokeswoman.

Separately, Comair, a Delta Air Lines unit, resumed a "limited" flight schedule after grounding all of its 1,100 flights to 119 cities on Christmas day because of a computer system crash, said Tracey Bowden, a Delta spokeswoman.

The holiday travel plans of about 30,000 Comair passengers were scrambled on Saturday. Bowden could not estimate how many flights would take off on Sunday but said the number would rise over the next several days "with anticipation they will be operating a full schedule by the end of the week."

Comair mainly flies routes in the eastern half of the United States, including New York, Boston and Washington, and serves Delta's major hubs in Atlanta, Cincinnati and Salt Lake City.

The Federal Aviation Administration was set to help the two airlines reposition aircraft and crews for normal operations, said Greg Martin, a spokesman.

But "the problem is exclusive to their operations," not a federal air traffic control matter, he said, adding this would be of scant consolation to the thousands being inconvenienced.

Kudwa of US Airways said its woes began with "severe weather" over Philadelphia on Thursday, compounded by unusually high sick calls from baggage handlers there and a record 32,000 of the airline's passengers moving through the airport.

Over the weekend, thousands of US Airways passengers were separated from their luggage, a problem the airline was working around the clock to fix, also using an outside vendor to truck bags from Philadelphia, airline officials said.

US Airways, operating under the protection of bankruptcy court, has won major concessions from most of its employees but said it might start liquidating by mid-January in the absence of ratified pacts.

The company was flying some luggage from Philadelphia to its larger facility at Charlotte, North Carolina, to speed delivery. US Airways did not think the high volume of sick calls at Christmas was organized, Kudwa said.

"We don't believe that we have an organized labor action on our hands," she said.

(Reuters)