Q. Do airlines decrease and increase the number of seats available at advertised sale prices? I ask because last week I saw a sale advertised on an airline web site and went to find seats for my dates of travel but was unsuccessful. However, the next day my cousin, who was making the same trip to attend a wedding, found seats at the sale fare on the exact same flights I searched the day before.

A. There are many reasons why a sale fare might be unavailable one day but available the next. Airlines not only adjust fares, but also the number of seats available at those fares. And if someone has a sale fare on "hold" but doesn't buy it, the sale seat will go back into inventory. So it pays to be diligent and persistent.

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