Last Updated Nov 30, 2017 4:47 PM EST
DALLAS - American Airlines (AAL) is seeking to reassure travelers scheduled to fly in December that the carrier's flights will be ready for departure.
A glitch in the computer system American Airlines pilots use to schedule time off raised concerns this week thatand other essential personnel. The company said Thursday that only a few hundred of its late December flights remain without pilots scheduled to fly the plane.
"We have not canceled any scheduled flights in December and will continue to work to ensure both our pilots and our customers are cared for," the carrier said in a statement.
American Airlines spokesman Matt Miller said that pilots were picking up extra flights and that the number of unassigned flights was continuing to decrease. He also said the airline had more on-call pilots in December than during other months.
The Allied Pilots Association (APA) had said that more than 15,000 American Airlines flights scheduled between Dec. 17 and Dec. 31 lacked a captain, co-pilot or both when a problem was discovered in the company's scheduling system. Pilots were allowed to take vacation days in the last two weeks of December even if there wasn't another pilot available to operate the flight.
Despite American's claims that it is dealing with the scheduling problem, the APA said Thursday afternoon that its review of real-time data shows that "thousands" of the airline's flights have yet to be assigned crew.
As a result, "That data does not support management's statement regarding December flights that 'only a few hundred' are currently unassigned to pilots," the group said in a statement.
"We remain seriously concerned about the potential for significant schedule disruption for our passengers, pilots and fellow employees during the critical holiday travel season," the APA added.
The airline told CBS News it is keeping those flights open to pilots who wish to pick up trips at higher pay in order to reduce the number of flights that will have to be covered by reserve crews. American says that explains why trips appear unassigned in the system referred to by the pilot's union, but will be covered by reserve pilots if needed.
A letter sent to pilots this week and obtained by CBS News shows the bulk of the holes in the schedule are late in December. Americain Airlines is seeking captains and first officers for flights originating in cities including Boston, Charlotte, Chicago, Dallas, Miami, New York, Philadelphia, St. Louis and Washington D.C.
The carrier has about 15,000 pilots and roughly 200,000 flights scheduled during December.
American Airlines discovered the software issue the day after Thanksgiving and has been working since Black Friday to fill the unassigned flights, CBS News has learned. The glitch, which occurred with the system that allows pilots to drop or trade assigned trips, allowed thousands more pilots to be off during the Christmas travel season than it should have. It has since been fixed.
The airline has apologized to pilots for the inconvenience the error has caused.
"This was a terrible screw up by American Airlines," said Henry Harteveldt, president of Atmosphere Research Group, which tracks the airline industry. He recommends that people with tickets on American during the holiday travel season monitor the situation. He does not believe people need to change their travel plans just yet.
"Is there a risk some flights will be canceled? Yes, but I don't think the real number will be close to 15,000," he said.
Roughly 30 million people are expected to fly during the busy holiday season.