Airline passengers have many complaints these days — from cramped flights to security hassles. But one aspect of flying has improved: The odds of getting bumped from a flight are the lowest in more than a decade.

For the first nine months of the year, airlines bumped about 12 passengers per 10,000 from their scheduled flights, a USA TODAY analysis of government statistics since 1995 shows.

The overwhelming majority volunteered, induced by some sort of airline voucher or freebie. The low rate this year is a huge shift from the late 1990s, when passengers were nearly twice as likely to get bumped.

Government numbers show a steady decline in the rate of bumping over the past five years.

Strangely, this year's low rate of bumping comes as airlines are packing flights fuller than ever. In November, for instance, American Airlines, the world's largest carrier, filled 80.3 percent of its seats on U.S. flights.

Fuller flights theoretically should cause the rate of bumping to soar because they reduce the margin for error in overbooking, the industry practice of selling some seats twice to offset anticipated no-shows.

But rates are declining, says Peter Belobaba, an airline expert at the Massachusetts Institute of Technology, because airlines have become more precise in their overbooking. He credits improvements in information technology that permit better forecasting of the number of passengers who will fail to show up for their flight.

It also helps that airlines are seeing fewer no-shows, he says.

Industrywide, the no-show rate has fallen to about 12 percent of ticketed passengers, vs. about 20 percent in the late 1990s, Belobaba says.

"That inherently means that the no-show numbers are less variable, so it makes these statistical overbooking models perform better," Belobaba says.

The growth of Internet ticket sales discourages people from booking tickets without first paying for them, US Airways executive Scott Kirby says. "You can still book a non-refundable ticket without paying for it through an agent," Kirby says. "With the Internet, you can't do that."

As Web sales have risen, so has the popularity of cheaper non-refundable tickets. The restrictions on those tickets give passengers more incentive to show up, Belobaba says.

About four years ago, airlines started using software that lets them identify passengers who have double-booked flights, Kirby says. Passengers frequently will have a travel agent book two trips to keep travel options open. Kirby says the software allows airlines to identify and cancel trips that have been double-booked.

Airlines bump passengers involuntarily when a flight is overbooked and a sufficient number of passengers can't be induced to give up their seats.

Industrywide, the involuntary rate has generally hovered over the last decade around one in 10,000 passengers, or less than one-tenth the rate of voluntary bumping. In the late 1970s, airlines were bumping passengers involuntarily at a much higher rate — about seven per 10,000.

Involuntary-bumping rates have inched up this year over last year at Northwest, American, America West, US Airways, Delta and Continental. Of the big airlines, Continental this year had the highest rate, involuntarily bumping nearly two passengers per 10,000.

At United Airlines, the bumping rates fell this year to near 10-year lows, according to U.S. Department of Transportation data. United bumped, voluntarily and involuntarily, about 15 passengers per 10,000 this year through September.

"We're doing a better job of forecasting," says Robin Urbanski, a United spokeswoman, crediting improved technology.

Predictions of no-shows are complicated. Urbanski says the no-show rate varies by season, city and time of day. Typically, for example, no-show rates are higher for 6 a.m. flights, when people are more likely to oversleep. Flights scheduled around rush hours can be counted on for a high rate of no-shows.

Declines in bumping rates benefit consumers as well as airlines, Belobaba says. The airlines save money by not doling out goodies and passengers are likelier to complete their trips.