Technique: Accelerated stalls

Banking and yanking

September 1, 2016 By Ian J. Twombly

An airplane wing can stall at any attitude and any airspeed. It’s a truism we hear repeatedly. Yet most airplane handbooks publish only flaps-up and flaps-down stall numbers, and most pilots practice stalls only at those speeds. Many stalls happen at speeds higher than these slow, controlled speeds. They’re called accelerated stalls, and they can happen if the airplane is headed straight up, straight down, or anywhere in between. Generally, accelerated stalls are brought on by turning or by making abrupt control inputs. To practice an accelerated stall, try these steps:

Illustration by Charles Floyd

Load factor

When an airplane turns, its load factor, or airframe stress, increases. That’s the feeling of being pulled down harder in the seat. Regardless of the type of airplane, the load factor increases at a predictable rate. At 45 degrees of bank in a level turn, for example, the load factor is 1.4, meaning gravity will feel 40 percent stronger.

The biggest impact of load factor is on stall speed. It increases at the square root of the load factor. A 45-degree bank increases stall speed by 18 percent, and a 60-degree bank increases it by 40 percent!

Coordination

As with the approach and departure stalls we commonly practice, being coordinated helps immensely with accelerated stall recovery. If the rudder isn’t coordinated, the nose won’t fall to the natural, central position. Too much rudder on the inside of the turn will cause a spin, and it will happen quickly. Even outside rudder can lead to a spin, although not as easily. One reason traffic pattern stalls are often unrecoverable is because the airplane frequently wasn’t coordinated.

Test standard

Private pilots don’t have to demonstrate accelerated stalls on the practical test, but the Private Pilot Airman Certification Standards lists them in both the knowledge and risk management sections of steep turns and power-on stalls. That means an examiner will expect the applicant to be aware of accelerated stalls, know when and why they happen, and be able to describe how to avoid accelerated stalls and recover from them.

Ian J. Twombly

Ian J. Twombly is senior content producer for AOPA Media.

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