United Airlines apologizes for use of Sept. 11 flight numbers

United Airlines apologized on Wednesday for inadvertently reactivating the retired flight numbers of its two planes that crashed after being hijacked by terrorists on Sept. 11, 2001.

The flight numbers were assigned by a computer late Monday for sales of future flights, said airline spokesman Rahsaan Johnson. Early Wednesday, airline officials noticed the error and immediately removed them from the system.

“We did not make a decision to use those flight numbers,” Johnson said. “The error was technical.”

Photos: The terrorist attacks of Sept. 11, 2001

Although not required by the Federal Aviation Administration, airlines typically retire the numbers of flights involved in fatal crashes, an FAA spokeswoman said.

United Flight 93 was hijacked while en route to San Francisco from Newark, N.J., and crashed near Shanksville, Pa., killing all 44 people aboard. United Flight 175, traveling from Boston to Los Angeles, was hijacked and crashed into the south tower of the World Trade Center in New York with 65 people aboard.

Though the upcoming flights will be operated by Continental Airlines, they were given a United flight number under a code-share agreement between the two airlines. United and Continental merged in October and became United Continental Holdings Inc.; they are in the process of combining their flight operations.

Because the numbers were assigned for sales of future flights, they did not appear on screens at airport check-in counters, departure/arrivals monitors or gates.

However, it is possible that the numbers were displayed on airline and travel websites for reservations, Johnson said.

Johnson declined to comment on whether any tickets were sold with the flight numbers. If any were purchased, customers will receive a new itinerary and flight number, he said.

American Airlines also retired the flight numbers of its two planes used in the Sept. 11 attacks.

Photos: The terrorist attacks of Sept. 11, 2001

stephen.ceasar@latimes.com