You have to be a bit of an airline geek to get this.

Took this shot a few moments back sitting in a flight at La Guardia airport while taxiing to the runway.

Do you see anything unique about the picture?

As I saw the airplanes rolling one by one to the head of the runway, suddenly something in the sequence caught my eye.

There are 5 airplanes in the sequence. Each from a different airline. And those are the top 5 airlines in the USA (by capacity)!!!

How unique is that?

For the data-oriented, measured in ASMs, here is the ranking from May this year.
#1. United Airlines (65.7 billion)
#2. American Airlines (65 billion)
#3. Delta Air Lines (61.3 billion)
#4. Southwest Airlines (38 billion)
#5. JetBlue (16.7 billion)

Note that the ranking order will get interchanged if you go by other metrics like passenger footfalls, miles flown etc etc.