In this Jan. 29 photo, an American Airlines passenger plane takes off at Miami International Airport in Miami. (Alan Diaz/Associated Press)

Beleaguered American Airlines, emerging from bankruptcy and into a forced merger, had to ground about 900 flights on Tuesday after its computer system broke down.

With the approval of the Federal Aviation Administration, American grounded its flights until 5 p.m. Tuesday to sort out troubles with the computer system that handles reservations and allows gate agents to print boarding passes.

By that hour, American announced that its systems were back up and processing information. But the impact of the grounding is expected to ripple into Wednesday because many of American’s planes won’t be at the airport where they were expected to start their day.

The grounding caused turmoil in airports across the nation, as thousands of passengers tried to book flights with other airlines and swarmed ticket counters demanding an explanation.

Without working computers, ticket counter personnel could not check in passengers, issue baggage receipts or produce boarding passes. Flights to American’s big hub airports in Miami, Chicago, Los Angeles, Dallas and New York were delayed for an additional half-hour.

American spokesman Michael Trevino issued a statement by e-mail, saying that the airline “network system is experiencing intermittent outages. We apologize to our customers for any inconvenience.”

The airline said it would offer refunds or waive ticket-change charges for affected passengers.

American carries about 275,000 passengers each day and receives more than 239,000 calls from people seeking ticket reservations. The reservations feed into a system called Sabre, which also handles reservations for other airlines, including Jet Blue and Southwest.

American first announced its problems with a tweet: “Our reservation & booking tool Sabre is offline.”

Sabre tweeted a response: “All Sabre systems are up and running — no issues here.”

Then American tweeted back a clarification: “The issue is w/ our ability to access our res system & not w/ @SabreNews. We apologize to Sabre & customers for confusion.”

A spokeswoman for Sabre later confirmed that the problem originated with American’s computer system, and she said none of the other airlines Sabre serves were affected.

There was no evidence that Tuesday’s grounding was related to American’s bankruptcy or to its planned merger with US Airways. The two airlines have not begun to merge their computer systems.

When United Airlines merged with Continental Airlines, the merger of their reservations systems provided passengers with a bumpy ride. In November, computer malfunctions resulted in 636 delayed flights, and last August a similar issue caused 580 delays.