Secondary Controls

You’re probably familiar with your airplane’s primary control surfaces, what they are, where they are and how they work. (If not, now’s a good time to research the topic.) According to the FAA, primary controls are those “required to control an aircraft safely during flight,” and are the rudder, ailerons and the elevator/stabilator of a conventional airplane. The pitch-control surfaces of a canard-configured airplane usually are considered primary controls, also.

Editorial Staff

Tuesday, July 22, 2014 at 12:00 AM ET

Verified

Key Takeaways:

Secondary flight controls (such as trim tabs, flaps, slats, and spoilers) augment primary controls, enhance aircraft performance—especially at low speeds—and serve specialized functions like increasing drag or reducing pilot workload.
Specific secondary controls like trim tabs alleviate control pressures, flaps and slats increase lift and drag for takeoff and landing, and spoilers assist with roll control, lift reduction, or rapid descents.
While less critical than primary control failures, malfunctions in secondary systems (e.g., pitch trim runaway or split flaps) can be challenging; however, these controls can also be crucial for maintaining aircraft control during emergencies if primary systems are compromised.

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Meanwhile, your airplane probably has some other control surfaces—known as secondary controls—which serve various functions. They often augment the primary controls but also can be used to change a wing’s shape, for example, which can improve low-speed performance. They also can be used in emergency situations. In some airplanes, moving what you think is a primary control actually changes a secondary control surface’s position, which then moves the primary surface. Let’s explore.