License to Learn

Responding to angle-of-attack warnings

Not long ago, researchers at Carnegie Mellon University discovered that using a cellphone while driving is distracting—it results in a 37-percent reduction in brain activity (and often it’s best to use your entire brain while driving). Since distractions often lead to accidents, common sense suggests eliminating this distraction. How? Don’t use a cellphone while driving.

Nearly 40 years ago, NASA researchers discovered that distractions while taking off or landing are responsible for the majority of stall/spin accidents in airplanes. Unfortunately, it’s often difficult to eliminate distractions in an airplane. What we can do is teach pilots the skills necessary to resist being distracted during critical phases of flight. Curiously, the FAA and NTSB have elected to attack this problem from a different angle by recommending that pilots install angle-of attack (AOA) indicators in their airplanes.

Other than a slow-running Hobbs meter, nothing would give me more pleasure than knowing that AOA would eliminate, or even substantially reduce, stall/spin accidents. No doubt the AOA indicator is a wonderful device for helping pilots better understand the concept of angle of attack. It’s also a useful device for informing them when the airplane’s wings are approaching their critical angle of attack. The problem with the previous sentence, however, is the word “informing.”

An early NASA study indicated that in those stall/spin accidents where the pilots survived, three out of four didn’t recall hearing the stall horn prior to the accident. Why? They were distracted, and distractions typically redirect a large percentage of our brain power to something other than controlling the airplane. We’re now less likely to behave properly in the presence of aural and visual cockpit warnings. The question is, how useful can an AOA be as a stall-prevention device when distractions keep pilots from paying attention to it?

To be fair, there are AOA indicators that do a better job of getting your attention—even when you’re distracted. These are models with verbal warnings, such as “Angle! Angle! Push!” Verbal warnings are superior to the continuous-tone warnings of your typical stall horn.

According to stall/spin expert Rich Stowell, author of the highly informative book Stall/Spin Awareness, an even more superior stall-warning device is a stick shaker. Unfortunately, the only stick shaker found in most GA airplanes is the flight instructor, who accompanies stick shaking with the following two phrases: “Let go of the controls!” and “I mean it this time.”

On the other hand, we shouldn’t expect AOA indicators to be the antidote for preventing stall/spin accidents. Consider that a 1971 NASA study suggested that the use of AOA, “did not show a significant improvement in performance and flight safety.” To date, no study has shown AOA as being effective in preventing stalls and spins. However, proper training—especially spin training—has been shown to have a positive effect on reducing spin accidents.

That said, if you’re going to use AOA, then give it the best chance of serving you. Become a distraction denier by learning to recognize and avoid those situations that increase your chances of being distracted. Modern-day distraction training doesn’t do the best job of helping pilots avoid distraction. It typically consists of an instructor tossing a pencil on the cockpit floor and asking the student to fetch it. The proper answer to that request is “No” or “No, pencils are evil!”

We might be better served if we elevate our cognitive game by training pilots to avoid those situations where we are likely to be distracted. For instance, we should avoid flying tight traffic patterns or patterns flown at low altitudes on base and final approach. Flying a tight pattern compresses the amount of time in which we have to act, and that increases our chance of being distracted. There’s no sense flying as if you’re in a Red Bull competition when Red Bull isn’t in town.

Flying low in the pattern requires that a pilot pay more attention to spying a hard-to-see runway, much less trying not to notice the rapidly moving ground beneath him. Stabilizing an approach on base and final approach with proper trim control reduces the likelihood that the airplane will deviate from the desired attitude if a pilot is distracted. If ATC says, “Can you make an immediate takeoff?” sometimes the best answer is, “No” or “No! Immediate takeoffs are evil!”

These are just a few of the many—many!—things you can do to avoid being distracted during takeoffs and landings. The payoff? If and when a stall alert appears in the cockpit, you’ll be more likely to notice it.

Web: www.rodmachado.com

Rod Machado will be a featured speaker at the AOPA Fly-In in Colorado Springs, Colorado, September 26.