United emerged from bankruptcy protection in February

Helped by strong demand and higher fares, the firm made a net profit of $190m (�99.5m) in the three months to the end of September.

This compares with a loss of $1.77bn for the same period in 2005.

UAL saw revenues grow to $5.18bn from $4.66bn, and said it would look for further ways to trim its costs.

Costs cut

United - the second-largest US airline after American Airlines - is just one of several established US carriers that has sought bankruptcy protection in recent years.

The airline had struggled with soaring costs, increased competition from low-cost rivals, and a dip in passenger numbers after the 11 September 2001 attacks.

The firm had used its bankruptcy protection to cut its costs by $7bn a year.

Under US Chapter 11 protection, a bankrupt firm can continue trading while being protected from its creditors, giving it time to restructure is finances.

Risks remain

Despite UAL's recovery, some analysts warn that further pitfalls lie ahead in the shape of high fuel prices and low-cost competition.

"We've reached a point where things are going very good for the industry," said Morningstar analyst Brian Nelson.

But he said large airlines such as United were still a bad long-term investment.

"Long-term industry fundamentals have not changed," he added.