When you travel by airplane you usually receive a seat assignment that includes and a letter. The number tells you which row you were assigned while the letter indicates your specific seat within the row. Commercial jets place letters on individual seats so that you will not get your row number and your seat number confused. This alphanumeric system makes it easier for you to find your assigned seats than an entirely numeric system.
Order of Letters
The amount of letters in each seating row depends on the aircraft's width. The farthest seat on the left-hand side of the plane is usually assigned the letter "A," with each subsequent seat receiving the next letter in the alphabet. Narrow planes with just two single-seat rows may have only a seat "A" and a seat "B," while wide jets for transcontinental flights tend to have seat letters ranging from "A" through "K." Most aircrafts skip the letters as "I", "S" and "O" because they closely resemble numbers.
Location of Letters
Check your boarding pass to find your row number and seat letter. When you reach your designated aisle, you can find the order of the seats posted below the overhead bins on either side of the row. While seat letters often progress in descending order from the left-hand side of the plane, you should always check the posted sign to be sure you take the correct seat. Seat numbers are also often listed on the seats themselves to prevent further confusion.
When you book a flight online you may be shown a seating chart that allows you to select your preferred row number and seat letter. Looking at the seating chart as you book your flight gives you an indication of which seats might be the most convenient and comfortable. Additionally, some websites (see Resources) rate the comfort level and amenities of different seats on various aircrafts. If you don't see a seating chart online, you can call the airline and ask them to send one to you.
Seat Letter Tips
If you the chance to choose your seat letter but do not have access to a seating chart, you can still try to choose your preferred seat. If you want an aisle seat, avoid "A" seats, since those are located next to the window on most airlines. In jets with three-seat wide rows, "C" seats" and "D" seats will usually be located closest to the aisle. Ask the airline about the number of seats in each row to give you an indication of which seat letter to select.