What causes the most trouble when you travel? Flying, according to the Orbitz Travel Survey.

Asked to cite their "most problematic" trip experiences, 40 percent of those surveyed cited flight delays and 21 percent said airport security. Only 15 percent said hotel amenities and cleanliness, while 9 percent cited rental cars.

The survey was conducted for Orbitz by the Ipsos Public Affairs Project.

Only 21 percent of those who fly said their travel time has not increased as a result of new security measures such as removing shoes and restrictions on liquids and gels.

However, the new security measures have left 42 percent feeling satisfied or more secure than before the Sept. 11 attacks, while another 46 percent said they feel somewhat safer but still think security could be improved.

Price was cited as the most important factor in booking a flight by 48 percent of those surveyed. But by a margin of more than 2:1, travelers said that if they could pick a flight amenity, they'd rather have more legroom than a free meal.

Only 24 percent of those surveyed do not use online travel sites. Among those who do go to the Internet, 31 percent characterized online customer service as good or outstanding and another 29 percent said it was satisfactory. Fifty-nine percent said "lowest prices" was the most important factor in choosing an online travel site.

The poll was conducted before the Federal Communications Commission decided to maintain the ban on cell phones in flight, but survey findings on the issue suggest that more people would agree with the FCC decision than not. The travel survey found that only 29 percent favored permitting cell phones; 49 percent did not.

The survey also found that younger Americans travel more than older Americans. A third of those ages 18-34 have traveled three or more times in the past year, while 35 percent of those ages 55 or older have not traveled at all. And those who are married appear to travel more often than those who are single - 61 percent versus 46 percent reported traveling twice or more in the past year.

The survey was conducted March 20-22 among 1,006 adults, 738 of whom had traveled in the past year. The margin of error was plus or minus 3 percentage points.