The literature on primary and secondary flight controls is very contradictory. My professor provided this image from which I infer that spoilers are used for primary flight control: enter image description here

Also, here it says that spoilers qualify as primary flight control.

On the other hand, Skybrary lists spoilers as secondary flight controls.

What kind of flight controls are spoilers?

  • 1
    $\begingroup$ It really depends on the aircraft: on the first versions of the B-52 for example, spoilers were the primary and only control surface. $\endgroup$
    – sophit
    Nov 29, 2022 at 19:49

2 Answers 2


There does not seem to be a consistent definition for primary and secondary flight controls. It depends on the aircraft.

The Airbus A310 FCOM distinguishes between primary and secondary controls as follows:

The primary flight controls ensure flight path control and include:

  • pitch control, using:
    • the elevators, which are hinged to the Trimmable Horizontal Stabilizer (THS), and
    • the Trimmable Horizontal Stabilizer (THS) which provides Pitch Trim.
  • roll control, using:
    • 1 aileron per wing, and
    • the 5 outboard spoilers (Nos. 3 to 7) on each upper wing surface, as roll spoilers.
  • yaw control, using a single rudder.

[...] The secondary flight controls are lift and drag augmenting devices and includes:

  • flaps: there are one double slotted inboard flap and on single slotted outboard flap.
  • slats: there are three slat sections per wing (inner, center and outer). Associated with the slats a Kruger flap is located on the leading edge of each wing, inboard of the inner slat section.
  • spoilers: there are 7 spoilers (Nos. 1 to 7) on each upper wing surface which are used as speed brakes, roll spoilers or ground spoilers for lift dumping (all 7 surfaces).

(emphasis mine)

Therefore, spoilers can be counted as primary controls, but only those which are actually used as roll spoilers (asymmetric deployment in the air).

As far as I could find, Airbus does not distinguish between primary and secondary controls in subsequent models.

The Boeing 747 FCOM (-400 and -8 models) defines the primary and secondary controls as follows:

The primary flight controls are elevators, ailerons, and rudders. [...]

Secondary flight controls include a moveable horizontal stabilizer, spoilers, and leading and trailing edge flaps.

(emphasis mine)

Here, spoilers are clearly excluded from the primary flight controls. Other Boeing FCOMs I found define the primary flight controls in a similar way, but do not go into further details about secondary flight controls.


It depends on the aircraft. For example:

  • On a Learjet 45 airplane. There are spoilers that are mainly used in the air to slow down and/or descend. However, when flaps are increased, those same spoilers become spoilerons and help the airplane roll. There is even a roll disconnect feature that will disconnect the pilot side yoke to the aileron cables and solely use the spoilerons to roll the aircraft.

To summarize I would say this

  • Spoilers are secondary flight controls. In the air, the help the airplane slow down and/or descend. On the ground, they are used to spoil lift and transfer the weight of the airplane to the wheels to aid in braking

  • Spoilerons are primary flight controls. They help the pilot maintain roll authority by either supplementing the ailerons or being the only way to roll the airplane.


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