Passenger revenue it collects for each seat flown one mile rose an estimated 2.5 percent to 3.5 percent for the month, according to the airline. Passenger revenue growth was strong compared to November, but was hurt by year-end adjustments.
That's a per-passenger figure, so it can rise even if the airline carries fewer passengers. It can also rise if remaining passengers paid more to fly.
Traffic — measured as one paying passenger flown one mile — fell 4 percent, according to the airline's announcement late Tuesday. Domestic traffic fell 5.9 percent, while international traffic was down 2 percent.
Flying capacity was down 5.4 percent, including a 6.1 percent cut in domestic capacity and a 4.2 percent drop in international capacity.
Because capacity shrank faster than demand, United's planes were fuller. Occupancy rose 1.2 percentage points to 82.4 percent.
United shrank for the full year, too. Traffic fell 1 percent across its system because of a 2.5 percent drop in domestic traffic. International traffic showed a 0.1 percent gain.
The airline cut full-year flying capacity by 1.5 percent. That included a 1.7 percent cut in the flying it does on regional carriers it hires to fly under the United Express name.
Occupancy for the year rose 0.4 percentage points to 82.6 percent.