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 control surfaces, such as trim tabs, flaps, slats, and spoilers, augment primary flight controls, enhance aircraft performance (e.g., low-speed lift, rapid descent), and improve handling across different flight regimes.
Each type serves a specific function: trim tabs alleviate control pressures for hands-off flight, flaps and slats increase lift and drag for takeoff/landing, and spoilers reduce lift for roll control or rapid descents.
While failures of secondary controls are generally less critical than primary ones, they can still present challenges; conversely, these systems can be crucial in emergencies, providing alternative control in situations like a jammed primary control surface.

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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.