Alaska Airlines said it carried fewer passengers in August compared with the same month a year earlier. But the airline’s planes are fuller and its on-time performance has improved.

The airline, a subsidiary of Alaska Air Group Inc. of Seattle, reported the number of revenue passenger miles (the number of revenue-paying passengers multiplied by the distance traveled in miles) fell to 1.78 billion from 1.79 billion in 2008, or a decrease of 0.8 percent. The airline’s available seat miles (the number of seats available multiplied by the number of miles flown) fell 2.9 percent to 2.11 billion from 2.17 billion a year earlier. And its revenue passengers fell 7.5 percent to 1.5 billion from 1.6 billion in 2008.

The airline’s passenger load factor (percentage of available seats occupied by fare-paying passengers) rose to 84.3 percent from 82.5 percent a year earlier.

Alaska’s on-time performance for August increased from a year earlier, improving to 85.7 percent last month compared with 78.7 percent in August 2008.

At sister airline Horizon Air, revenue passenger miles fell nearly 12 percent to 229 million from 260 million a year earlier and available seat miles fell by nearly 13 percent to 289 million from 332 million in 2008. The number of revenue passengers fell by 11 percent to 622,000 from 699,000 a year earlier. Horizon’s passenger load factor rose to 79.2 percent from 78.1 percent and its on-time performance rose to 88.6 percent from 84 percent a year earlier.