Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Thunderbirds are the air demonstration squadron of the U.S. Air Force (USAF), based at Nellis AFB in Las Vegas, Nevada. The squadron tours the United States and much of the world, performing aerobatic formation and solo flying in pecially-marked USAF jet aircraft. Officers serve a two-year assignment with the squadron, while enlisted personnel serve three to four. Replacements must be trained for about half of the team each year, providing a constant mix of experience. The squadron performs no more than 88 air demonstrations each year and has never canceled a demonstration due to maintenance difficulty.