Passengers pat the plane when they board, as if to make sure it's solid. Some kiss the fuselage, or even break into the same little dance, at the doorway every time they fly. If they peer into the cockpit, they may see pilots' hats hanging with family pictures stuffed inside for good luck.

Even airlines have set ideas about good and bad mojo, down to a list of verboten flight numbers: No one ever schedules Flight 13.

Travel is chock full of little superstitions, fluky talismans and fateful traditions, such as retiring the flight numbers of crashed planes. Of 102 airlines tracked by SeatGuru.com, 25 around the world have no Row 13s on their planes.

Before it merged with United Airlines, Continental Airlines avoided the number 13 religiously: no gate 13s at hub airports, no row 13s on airplanes.

Veterans from the airline say the triskaidekaphobia followed the crash of Flight 1713 in Denver in 1987. 'After that, a lot of 13s were taken out of Continental Airlines,' said an executive who worked there at the time.

Construction workers top airport control towers with a ceremonial cedar tree, a constructiontradition for good luck. Airlines sometimes put perceived lucky numbers on flights to gambling destinations, such as Southwest Airlines Flight 711 from San Antonio to Las Vegas.

Alaska Airlines flies many Canadian customers from Las Vegas to Bellingham, Wash., so it numbered the flight 649, a spokeswoman says, because Canada's lottery is called Lotto 6/49.

Airlines say tradition calls for them to retireflight numbers of crashed jets. Alaska Airlines says that in addition to 13, 666 and 911, it will never number a flight 261 out of respect to the victims of the Flight 261 crash in 2000. US Airways hasn't used Flight 1549 since the 2009 crash that saw pilot Chesley Sullenberger famously land his crippled plane in New York's Hudson River, saving all on board.

American Airlines and United both retiredflight numbers from the Sept. 11 terrorist attacks. American and Delta Air Lines both had fatal crashes of Flight 191s, and so no longer use that number.

Indeed, 191 has been involved in several aviation accidents, from the 1967 crash of an X-15 experimental military plane flying as Flight 191 to the crash of Comair Flight 5191 in 2006 that killed 49 people in Lexington, Ky. Last year, JetBlue Airways Flight 191 diverted to Amarillo, Texas, after the captain displayed alarming behavior, was locked out of the cockpit and restrained by passengers.

Many airlines and airports insist that the lack of row 13s or gate 13s isn't the result of superstitions. Rather, they often skip numbers so that gates and rows can be rearranged without having to renumber every gate or row, and to provide uniform seat numbers across different types of airplanes. United, for example, always starts the first mid-cabin exit row of coach at Row 20. Still, many planes follow row 12 with row 14.

United doesn't have an aversion to Row 13, and has one on many of its planes, a spokesman said, adding he didn't know where Continental's avoidance of the number started. When its fleet merged with Continental, however, row numbering was standardized so planes could be easily swapped, and so Row 13 is skipped on all Boeing 737s and most versions of the 757.

Cleveland Hopkins International Airport, a former Continental Airlines hub, has no Gate 13s. A spokeswoman says she polled airport employees and could not determine how that came to be. 'It's all before any of us were probably born,' she said.

Most travelers know flying is statistically safer than driving, but there's still unease for many passengers when metal machines defy gravity. And superstitions dating to the early days when flying was riskier have persisted. Flight attendants suggest the increased stresses of travel have led to increased comfort mechanisms -- little habits to ease minds and reassure.

As a lead flight attendant, Bobby Laurie greets passengers at the front of the airplane during boarding, and has observed an increasing number of superstitious habits, from tapping and kissing the plane to jigs and dances in the jetway. When he asks, some people say family members have done it and they've been told it brings good luck.

'Every day I see a lot of the same mannerisms,' he said. 'Boarding is like watching a show sometimes.'

Two regulars on flights between Los Angeles and Washington wear the same shirt whenever flying, Mr. Laurie said. Some people travel with the same blanket. One woman insisted a stuffed monkey be belted in with her on every flight for good luck.

'Some people have emotional-support animals. Some people have emotional-support shirts,' he said.

Others just have habits that they need to repeat on every flight. Brian Cohen's first international flight, to Paris during his college years, included listening to the 1975 Elton John album 'Captain Fantastic and the Brown Dirt Cowboy' on a borrowed Sony Walkman.

Every time since on international flights, he has played the same songs at the same phase of flight. He tries to make it look like his headphones are plugged into the plane's entertainmentsystem and hides his player to avoid scolding from flight attendants about electronic-device rules.

The song 'Bitter Fingers' is timed so the second chorus plays as the jet is taking off. (If the flight is delayed, he plays the previous song over and over. That's easier to do in the digital music era than when he used a cassette tape.) 'Someone Saved My Life Tonight' comes on as the plane is soaring to cruising altitude.

'I call it a pleasurable tradition, not a superstition,' said Mr. Cohen, who lives in Atlanta.

He, too, says he sees more people with more habits these days, such as crossing themselves before takeoff. He thinks it's more because of stress than fear of flying. And some flying traditions, such as applauding when a plane lands, are just annoying, he notes.

Of course, not everyone in the travel industry bows to superstition. The Las Vegas Hotel, formerly the Las Vegas Hilton and a huge structure deeply rooted in the Mecca of U.S. gambling, has Floor 13. Most Vegas hotels, like many hotels and office buildings around the world, skip what is considered an unlucky number, and label floors so that 14 follows 12, or even 12A.