It's probably the worst way to start a vacation -- to have your wallet, camera or even passport stolen while you are sleeping on a plane.
Travel experts say it is rare but does happen. Two high-profile cases in recent days are raising awareness to the issue.
The 22-year-year son of actress Cybill Shepherd was arrested this week after he was caught allegedly rifling through his fellow passengers' carry-on bags. Cyrus Shepherd-Oppenheim allegedly took a Canon digital camera, leather make-up case and cash from passengers aboard a United Airlines flight from San Francisco to Philadelphia. After landing around midnight, two passengers reported the missing items and witnesses identified Shepherd-Oppenheim.
Air France apologized for the incident but added that the flight attendants are on board to ensure the safety of the plane and its passengers and cannot police the aircraft to avoid theft.
"Theft on airplanes is rare," said Bill Miller, an executive with booking site CheapOair. "In my experience of 22 years in the travel business, this is not something that's talked about much and I don't see it happen often."
Miller suggested placing your bag's zipper away from the overhead bin's opening, bringing a lock for your carry-on bags and becoming acquainted with your seat mate.
But George Hobica, an airline expert and president of Airfarewatchdog, said such thefts actually do happen "more than you'd think."
"People fall asleep on planes, and someone can reach under the seat in back of them to steal stuff from carry-on luggage under the seat or in the overhead, especially on overnight flights," Hobica said. "It's really important to use a sturdy lock to seal up your carry-on luggage. And don't leave wallets in coat pockets in the overhead, or even in the closet if you're in first/business class."
Travelers also should be aware of sleeping pills and other drugs, said Best Western's business travel blogger Chris McGinnis.
When he was traveling in Spain years ago, he got bad allergies and took a decongestant "that really knocked me out."
"I got on the train, entered an empty passenger cabin, threw my backpack on the overhead rack and fell asleep for nearly the entire night," McGinnis said. "I got off the train in Madrid and found that my camera was gone."
It might have fallen out or been lost, but to this day, McGinnis assumes it was stolen. The lesson: Remember that medication might make you unaware of your surroundings.
Anne Banas, executive editor of SmarterTravel added that airplane passengers need to be aware of their surroundings at all times, just like they would in any other situation.
"I think there is a misconception on planes that you need to trust someone who is in such close proximity to you, but it's not always the case that you can," Banas said. "Some of the recommendations I give my readers include: don't put your wallet in the overhead compartment, keep it on you at all times while in flight. Always take your purse or wallet with you when you go to the bathroom."
If you take a nap, she added, make sure your wallet and high-priced personal items like iPods and cell phones are secure.