How to recognize and fight airline tricks

There have been hundreds of media stories in the last week about the Delta Airlines website “glitch” that overcharged members of its loyalty program on airfare across the board, but what none of those stories tells us is how to recognize and fight such airline practices — whether deliberate or accidental.

As this column has pointed out before, airlines try to overcharge customers all the time, and a decade ago, I used to fall for some of those tricks. That’s why I decided to learn the system — and that’s one of the reasons I wrote “Decoding Air Travel.” If you ever needed proof that knowledge means power, look no farther.

So how could you have known that the Delta website was charging you more than the lowest available fare? First, you have to understand what an airline tariff is: A list of all published base fares on a certain route, along with their rules and permitted routing — they carry a code corresponding to a letter of the alphabet. The second thing is the flight inventory, or the number of seats in each booking class made available on a certain flight…