[2Jedismom]

Wonder why it says WN??

I see where there is a current 108 that has landed.

[Overtaxed]

This 108 leaves at 12:15.

[HairOfTheDog]

Those are the Airline codes.... some are more obvious than others, like the aiport codes. MCO is Orlando.

you can enter the codes and flight numbers at the bottom in 'advanced user' search.

[ecurbh]

Wonder why it says WN??

Because WN is the 2-letter airline abbreviation code for Southwest Airlines. Some, such as UA for United Airlines or US for USAir make more sense than others.