Allegiant Air, which ferries travelers from smaller cities to resort locations in Florida and elsewhere, said Tuesday that traffic jumped 18.6 percent in December compared with a year earlier.
Allegiant said paying passengers flew 406.2 million miles last month, up from 342.6 million miles in December 2008.
The Las Vegas-based airline and travel company added flights and increased capacity by 16.1 percent, to 448.4 million available seat miles. A plane with 100 seats flying 100 miles is 10,000 available seat miles.
With traffic outstripping the additional supply of seats, the average plane was more crowded. Average occupancy in December was 90.6 percent, compared with 88.7 percent a year earlier.
For the year, traffic rose 28.1 percent as paying passengers flew 4.48 billion miles. Capacity increased 27.4 percent, to 4.95 billion available seat miles, and average occupancy or load factor rose to 90.4 percent from 89.9 percent.
Shares of parent Allegiant Travel Co. rose 74 cents to $48.75 in midday trading.