Chicago-based United Airlines said per-seat revenue rose as much as 12.5 percent in December as it benefited from flight cancellations and adjustments for tickets involving other airlines.
Other airlines have noted a benefit from the unusually late Thanksgiving, which had travelers returning home in December at the end of the holiday weekend. Earlier Wednesday, Southwest Airlines reported a gain of as much as 15 percent in December revenue for each seat flown one mile. Last week Delta said that revenue rose 10 percent, which was a bigger gain than it had expected.
United said traffic grew 4.1 percent in December, and was strong throughout the month. The revenue for each seat flown one mile rose an estimated 11.5 percent to 12.5 percent, more than United had originally expected, because traffic grew and United collected more from passengers.
In a perverse bit of airline financial logic, it also benefited from canceling more than 1,200 flights because of December storms. That's because the cancellations meant it flew fewer seats around, boosting its per-seat revenue for the remaining seats.
The storms and the accounting for tickets involving other airlines boosted the monthly revenue figure by 2.5 percentage points, United said.
United said it will stop issuing monthly revenue figures starting with its report for January.
United capacity for the month rose a half-percent, muted by those weather cancellations. Because traffic rose faster than capacity, its planes were fuller. Occupancy rose 3 percentage points to 85.4 percent.
For all of 2013, United traffic fell 0.2 percent, with domestic traffic down 1.2 percent and a slight gain in international.
United's capacity fell 1.4 percent for the year.
Its planes finished the year slightly fuller, with occupancy averaging 83.6 percent, up by 1 percentage point.
Shares of Chicago-based United Continental Holdings Inc. had risen $2.33, or 6 percent, to close at $41.02 before the report was released, after setting a new 52-week high of $41.06 earlier on Wednesday.
Counting the recently-merged American and US Airways as one carrier, United is the nation's second-biggest airline by traffic.