Welcome to Flyer Talk Spudee

Each letter represents a booking class, and is sorted from highest to lowest alphabetically (some tools sort from highest to lowest booking class but not seatcounter). Each fare generally uses a particular booking class. Higher fares booking into higher booking classes than lower fares.

Each airline has it's own mapping of booking classes. Some common ones are F for full fare first class, A for discounted fare first class, J C D for business class, Y for full fare economy class, B H M V W etc for cheaper economy class fares.

Airlines make more seats available in the more expensive booking classes. They usually limit how many show in the display to either 9, 7 or 4. Don't add up the numbers to get the total number of available seats in a particular cabin - it doesn't work like that. 9 means there are at least 9. You can get an idea of how full a cabin is by how many seats are available in the cheap booking classes - lots = flight is not yet very full, none = flight may be close to full or totally full.

There are more intracacies for expert users (revenue/yield management is very complex) but this should hopefully be enough to get you started.