Nearly a week after a computer glitch grounded hundreds of its planes, American Airlines has yet to disclose the exact cause of the problem that frustrated passengers stuck in crowded terminals across the country.

American’s chief executive, Tom Horton, would say in a video apology only that “we had a software issue that impacted both our primary and backup systems.”

But as airline computer systems become more interactive and complicated, computer experts warn that outages may become more common if airlines do not regularly test and maintain their systems.

“We are pushing the limits of human capabilities with these things,” said Bill Curtis, senior vice president and chief scientist at Cast, a software analysis and measurement company in New York. “What’s happening is these systems have gotten larger than any single person or single team can handle.”

American’s computer outage, which lasted two to three hours Tuesday, will probably force the airline to move with caution when it begins its merger with US Airways, said Farokh Bastani, a computer science professor at the University of Texas at Dallas.

Once the merger is approved, US Airways plans to transfer its reservations data to American’s computer system, officials from both airlines said.

“If some problems happen before any merger is taking place, it raises the possibility of problems when they integrate the systems,” Bastani said.

By the end of the week, American’s system seemed to be operating normally. Still, the airline and its regional carrier, American Eagle, canceled several hundred flights because of a non-technical problem: foul weather around Dallas and Chicago.

(c)2013 Los Angeles Times. Distributed by MCT Information Services.