The Spin Debate
If spins can kill, why aren't pilots trained to handle them?
- By Joseph Bourque
- Air & Space magazine, November 2003
NASA Langley Research Center
(Page 5 of 5)
For the NASA experiments his group acquired four general aviation aircraft that they modified radically to examine how changes to the standard airframe would affect spin characteristics. “The goal was to determine what was happening with spins, at least at first,” Patton says. His test flights with various aircraft modifications soon indicated that very small changes to the wing would produce huge differences in performance. “With simple changes to the wing we could change an airplane that flew like a kiddie car into a tiger that would eat you up,” he recalls. Thus came the realization that, with slight modifications, an airplane could be produced that was even more resistant to spins. The experimenters could say: “Hey, this is a very safe airplane. Not spin-proof, but it gives plenty of warning, lots of buffet, very little roll-off laterally—a long period of telling the pilot ‘Hey, you’re doing something wrong.’ ” In fact, a new generation of aircraft, particularly Lancair and Cirrus, use wing leading edge cuffs that were pioneered in Patton’s program. The cuffs, which improve the stall characteristics of an aircraft with only a negligible reduction in its performance, increase the radius of the wing’s leading edge and are attached so that there is a disruptive edge between the cuff and the wing itself. The effect of the cuff is to keep a stall from progressing from the inboard section of the wing to the outboard section.
Both the General Aviation Manufacturers Association and the FAA also believe in the importance of increasing the spin resistance of aircraft. In fact, the FAA argues that newer airplanes are less spin-prone, so there is less need for spin training. For that reason, Russell Lee, a private pilot and aeronautics curator at the National Air and Space Museum, thinks that obtaining a private pilot’s license should not require spin recovery training. He feels that many modern training-level and entry-level aircraft behave so well when operated according to the flight handbook that spin training to fly these airplanes is not necessary. “I think that in the vast majority of mainstream aircraft to which private pilots have access, there are simply too many clues designed into the aircraft to tell the pilot that he is headed for a spin,” says Lee. “Decaying airspeed is signalled not only by several instruments, but by a drop in wind noise and a drop in control pressures. Then there is pitch attitude change and stall warning—and all this happens before the airplane actually stalls. Most [modern training aircraft] types must then be held in the stall for some seconds to even fall off on a wing. To enter a genuine, full-rotation spin requires, in my experience with entry-level aircraft, aggressive use of pro-spin control movements such that the pilot has to purposely force the aircraft to spin.”
Lee has himself gone through spin training, and he says that it has made him a “better pilot, more prepared for unusual attitudes due to turbulence.” Though he doesn’t think spin training is necessary for beginning pilots, he does believe that once pilots graduate from entry-level aircraft to high-performance ones, they should get full spin training, or else they are putting themselves and those around them at risk.
Though new aircraft designs improve spin resistance, there are pilots still flying thousands of aircraft with less spin resistance, and some of them are going to find themselves in deadly spins. The real question is whether any of these lives might be saved by spin entry and recovery training. The FAA’s 1976 study sends a mixed message, so perhaps it’s time for a new study with a larger, more statistically valid sample. In the meantime, I’ll go spin every now and then, learn all I can, and try to avoid being the one who makes that fatal mistake.