Why has pilferage declined? "Since September 11, thieves seem to be intimidated by the increase in security at the airport," says Larry Ratti, a sergeant at the San Francisco Police Department's Airport Bureau. "It used to be that maybe five bags a month were being stolen at SFO, and now it's down to maybe one and sometimes even none."

The police at both San Francisco International and Los Angeles International airports do have undercover officers who monitor carousels. And when problems arise, the airlines and airports sound an alert. "If we're looking for a particular thief, we quickly start providing more security," says Louis Hoffman, a sergeant with the Los Angeles Airport Police.

But what travelers really need to worry about is someone picking up their suitcase by mistake. "Theft does occur, but much more frequently someone else's bag ends up in the hands of another passenger," says Debbie Millett, a spokeswoman for McCarran International Airport in Las Vegas. "There are a lot of black bags out there."

To avoid mix-ups:

• Tie a bright ribbon around the handle to distinguish your suitcase from others.
• Put a tag with your name and a phone number where you can be reached both inside and outside your bag.
• Always double-check to make sure that the bag you've grabbed is really yours.
• Try to get to the carousel quickly, so you're there when your luggage arrives.