(MONEY Magazine) – Despite the public's spreading fear of flying, more people than ever before are traveling that way, and the airlines are taking full advantage of the demand by raising prices about 15%, on average, from a year ago. Fares -- and accompanying restrictions or penalties -- vary greatly, as the table shows. For example: unrestricted one-way flights between Chicago and San Francisco cost $149 to $515. Here are some tips for the upcoming holiday season: -- Don't specify a time of day. You will be told only about flights for that time; for example, flying at night is 25% cheaper than during the day. -- Be flexible about the day you want to travel. Fares are often $10 to $20 higher on weekends compared with those between Monday noon and Thursday noon. -- Consider flying on a holiday. The day before is a ''blackout'' day, when many bargain fares are not available. -- Go out of your way for connecting flights that are cheaper than nonstop routes. -- Check out alternative airports. You may save 50% or more by flying to Newark rather than JFK. -- Plan ahead. Book early to get discounts. But if you think you may cancel, pay a little more to get a ticket that provides as large a refund as possible.

CHART: TEXT NOT AVAILABLE CREDIT: NO CREDIT CAPTION: NO CAPTION DESCRIPTION: Compares various airfares on several routes to several destinations.