As you know, there are many different kinds of pilots: private pilots, helicopter pilots, captains of airline transports (for the record, my brother is an airline transport pilot).
Over the past decade we’ve seen a remarkable growth in airline travel. 50 billion miles flown in 2001 vs. 867 billion miles in 2011. (Source: Advisory Council for Transportation Statistics: 2001 data, 2011 data.)
Amazingly, the total number of US pilots has stayed roughly the same—except in one category.
Today’s question: What is the one category of pilot (that is, with a specific kind of US pilot’s license—such as commercial, airline transport, helicopter, etc.) that has more than DOUBLED between 2001 and 2011?
See if you can figure it out! (Your first task is to find out how many different kinds of pilot licenses there are...)
As usual, please include HOW you figured it out and your best estimate about how long it took you to solve the challenge.