Trading in shares of American Airlines was temporarily halted on Monday for the second time this month.

The halt, triggered automatically when the share price of American parent company AMR fell dramatically, came after the airline and its pilots union failed over the weekend to agree on a new contact.

Trading also paused on Oct. 3 when the price fell amid speculation about the airline possibly restructuring under bankruptcy protection. AMR said that wasn't what the airline intended or wanted to do.

The volatility points up concerns about the airline's future.

"I think there's just a lot of concern about what's going to be the fate of the company," said airline analyst Basili Alukos of investment research firm Morningstar. "The thinking is if there is no deal (with pilots), that increases the likelihood it is going to look at bankruptcy or some other means to renegotiate those contracts."

When it reports earnings for the third quarter on Wednesday, analysts expect it to be the lone major U.S. carrier to show a loss - just as it was the only major one not to post a profit at the end of last year.

American said there was "no company-driven news" that caused Monday's volatility. AMR shares fell 18 cents, or 6.1%, to close at US$2.76, after falling to US$2.61 earlier.

But American spokeswoman Missy Cousino said the airline and pilots union plan to meet later this week.

"While some work remains, we are optimistic and believe there is a path to an agreement," she said.

Henry Harteveldt, co-founder of Atmosphere Research Group, a travel-focused market research company, said Monday's scare could serve as "a big motivator to both the airline and the pilots to get their acts together and try to find an arrangement."

American faces several challenges. It's become the third-largest U.S. carrier as United and Continental merge and Delta and Northwest already have. It has the highest labor costs of any U.S. airline and high fuel and maintenance costs because of an aging fleet.

It has pared flights to match the number of passengers wanting to fly and has ordered hundreds of new planes.

"We know we need to improve our results, and we are keenly focused as we work to achieve that," American spokesman Andrew Backover said earlier this month.