GENEVA — If you've ever been frustrated after an airline lost your luggage, you're in the good company of millions of others.

An estimated 30 million bags were temporarily lost by airlines in 2005, and 200,000 of those bags were never reunited with their owners, according to an industry report released yesterday.

The report by SITA Inc., a company that provides technology solutions for the air transport industry, also noted that "the problem of mishandled baggage is worsening on both sides of the Atlantic."

The 30 million misdirected bags comprised 1 percent of the 3 billion bags processed last year by airports, up from 0.7 percent in 2004, said SITA, which is promoting technology it says would reduce the problem.

Last year, mishandled luggage cost world airlines $2.5 billion, compared with $1.6 billion in 2004, SITA said, in a report released before today's airline and airport passenger services exposition in Paris. The jump partly reflects improvements in data collection, but also the increasing costs resulting from inadequate baggage management.

Greater airport congestion, tight connection times, increased transfers among airlines and stricter security are all contributing to more late or missing bags, said SITA, a Geneva-based company that is owned by the airlines, airports and other international air transport industry companies.

But the biggest problem is the growing number of passengers, whose additional bags cause delays and complicate handling, it said.

"Growth is welcome but it has to be better managed if airlines and airports want to improve the passenger experience by eliminating delays from the system," said Francesco Violante, SITA's managing director.

Mishandling during baggage transfer was the largest single cause last year of a bag failing to arrive with its owner at the intended destination. Other bags were temporarily lost because of airport personnel failing to properly load baggage, ticketing errors, problems with loading or unloading, and weight or size restrictions. Only 3 percent of all misdirection of baggage occurred due to tagging errors.

On average, bags are returned to their owners a little more than 31 hours — or 1.3 days — after they are reported missing, SITA said.

There is no industry standard for permanently lost bags, and items in some countries are later sold at auction.

In the United States, the Unclaimed Baggage Center in Scottsboro, Ala., sells more than 1 million items each year. Most of the merchandise sold is clothing, but also includes cameras, electronics, sporting goods, jewelry and — of course — luggage.

To help the airline industry cope with more passengers and more bags, SITA is promoting use of a tiny computer-style chip on luggage tags that it says will reduce the number of misdirected bags. The luggage labels, known as RFID for radio frequency identification tags, allow for tracking of luggage at all times over wireless networks.

The RFID chips also allow for quick removal of baggage from airplanes when the passenger who checked them fails to show up for the flight, SITA said. But the chips are used at only a limited number of airports so far.

"The industry needs more sophisticated baggage reconciliation systems and greater use of self-service such as check-in through kiosks and on the Web," Violante said. "This will all help to simplify travel, reduce delays and baggage misconnections."

SITA also promotes new technologies aimed at allowing mobile phone use on flights and offers applications for air-to-ground communications and fares services. It had revenues in 2004 of $1.58 billion.