Q: I read somewhere, perhaps on your blog, that airfares are updated 3 times during the week, and once on Saturdays and Sundays at around 5 PM. So please explain this: last Sunday, I was looking for a one way fare from the New York City area, any airport, to Phoenix for travel on February. After much searching, I found a fare on Continental for $109 one way, for their first and last flights of the day. I had to confirm this with my husband, who was not at home at the time. A couple of hours later, I went back to Continental.com and the $109 fare was nowhere to be found. Instead, there were fares over $200! This was around 2 PM ET. So how do you explain this?

A: It's true that airlines do not file new fares on weekends until about 5 PM. However, what you encountered was seat availability. All the seats at the lower fare must have been sold out between the time you saw the fare and you checked with your husband and went back to book. When you see a strikingly low fare, you've got to jump on it. You have time to continue searching for your flight, and who knows, Continental may open up more seats at the lower fare.