18. Watch sunlight flashing through a spinning propeller and experience flicker vertigo, which can cause disorientation or loss of consciousness.
Ran off runway: Grumman American AA-5B, Nov. 1, 2008, Bridgeport, Connecticut
19. Enter “hot” (active) military airspace.
Crashed: Bell AH-1, Lockheed HC-130, Oct. 29, 2009, off the southern California coast
20. While making a constantrate turn in instrument conditions, move head abruptly, creating the Coriolis illusion of the aircraft simultaneously rolling, pitching, and yawing.
Crashed: Beechcraft Super King Air 200, Feb. 6, 2007, North Caicos Airport, British West Indies
21. Flirt with towering cumulonimbi.
Crashed: Beech 35-B33, Nov. 30, 2008, Homosassa Springs, Florida
22. Take off with frost on the wings.
Crashed: Cessna TU206, May 6, 2009, Bethel, Alaska
23. Inadequately secure a single-engine aircraft before hand-starting it via the propeller.
Ran into airport fence: Piper PA-15, Nov. 30, 2008, Pleasanton, Texas
24. Have a few beers before flying.
Emergency landing: Boeing 717-200, May 12, 2005, Union Star, Missouri
25. Begin any maneuver with the words, “Hey, watch this!”
Way Faster Than a Speeding Bullet
Mach is a relative measure (affected by air density and temperature); in the upper reaches of the atmosphere, Mach 25 is about 17,500 to 19,000 mph. According to a landmark study by DARPA (Defense Advanced Research Projects Agency), the theoretical upper limit of a scramjet is Mach 25. At that speed, a scramjet could take off, reach an altitude of 47 miles, and have enough momentum to glide into orbit around Earth. The space shuttle and most man-made satellites orbit Earth about every 90 minutes, which translates to an orbital velocity of Mach 25.
The 25-and-Under Club
Some airplanes were so special, expensive, or complex that their production runs fell short of 25 airplanes. Some examples: The 1950 Northrop YC-125 Raider utility transport (23 built); the 1970s-era Aérospatiale-British Aircraft Corporation Mach 2 Concorde airliner (20, with 14 entering service) and its Russian counterpart the Tupolev Tu-144 (16); the 1931 Northrop Alpha (17); the 1929 Lockheed Model 8 Sirius (15); the 1960s-era Lockheed A-12 (16); the 1955 Martin P6M SeaMaster (12), and the 1938 Boeing 307 Stratoliner (10).