An aileron is a hinged control surface on the outer trailing edge of each wing that allows a plane to roll left or right. When a pilot turns the control wheel (called a yoke) or tilts a side-stick, the ailerons on opposite wings move in opposite directions: one tilts up while the other tilts down. This creates unequal lift between the two wings, causing the plane to bank into a turn.
Where Ailerons Sit on the Wing
Ailerons are mounted on the rear (trailing) edge of each wing, close to the wingtips. Their outboard placement is deliberate: the farther from the plane’s centerline a control surface sits, the more leverage it has to roll the aircraft, much like pushing a door near its handle rather than near the hinge. If you’re looking out an airplane window near the back of the wing, you can spot the aileron as the hinged panel at the very tip that deflects up or down during turns.
Ailerons are easy to confuse with spoilers, which are panels that pop up from the top surface of the wing between the leading and trailing edges. If the moving part is at the trailing edge, it’s an aileron. If it rises from the middle of the wing’s upper surface, it’s a spoiler.
How Ailerons Make a Plane Turn
A plane turns by first rolling, or banking, to one side. Ailerons make that happen by changing how much lift each wing produces. When the left aileron deflects downward, it increases the angle at which air meets the left wing, generating more lift on that side. At the same time, the right aileron deflects upward, reducing the right wing’s angle and producing less lift. The left wing rises, the right wing drops, and the plane rolls to the right. Once banked, the overall lift on the wings is tilted, pulling the plane into a curved flight path.
This always works in opposition. You cannot deflect both ailerons the same direction during normal flight. A cable or electronic link ensures that when one goes up, the other goes down.
From the Cockpit to the Wing
In a traditional small airplane, the connection between pilot and aileron is surprisingly mechanical. Turning the yoke moves cables that run through a series of pulleys down to the cabin floor, then back toward the tail, up the door posts, and across the ceiling before heading out into each wing. The cables cross over inside the fuselage so that the cable running up the left side routes out to the right wing, and vice versa.
At roughly the midpoint of each aileron, the cable connects to a device called a bellcrank, which converts the cable’s pulling motion into a push-pull rod that physically moves the aileron. A third cable strung directly between the two ailerons keeps tension in the system and guarantees that when one aileron moves up, the other moves down. In larger or more modern aircraft, hydraulic actuators or fly-by-wire electronics replace the cables, but the principle is the same: pilot input on one side produces opposite movement on each wing.
The Adverse Yaw Problem
Ailerons introduce an annoying side effect called adverse yaw. When you start a right turn, the left aileron deflects downward to generate extra lift on the left wing. But extra lift also means extra drag on that wing. Meanwhile, the right wing, with its aileron deflected up, produces less drag. The result is that the nose momentarily swings left, opposite the direction you’re trying to turn. Pilots correct this with rudder input, but aircraft designers have also come up with mechanical fixes built into the ailerons themselves.
One common solution is differential ailerons. In this design, the upward-moving aileron travels a greater distance than the downward-moving one. This increases drag on the descending wing just enough to counteract the extra drag on the rising wing, keeping the nose pointed in the right direction. Another approach, called the Frise-type aileron, offsets the hinge point so that when the trailing edge goes up, the aileron’s leading edge protrudes below the wing. That protruding edge creates drag on the descending wing side, balancing out the forces.
How Large Jets Handle Ailerons Differently
On a small Cessna, there’s one aileron per wing. Large commercial jets often have two on each wing: an inboard aileron closer to the fuselage and an outboard aileron near the wingtip. Both pairs are active during slow-speed flight, such as takeoff and landing, when the plane needs maximum roll authority. At higher cruise speeds, the outboard ailerons lock in place, and only the inboard ailerons remain active. This prevents the powerful outboard surfaces from overstressing the wing structure at speeds where even small deflections produce large forces.
At cruise speed, jets also rely on spoilers (those panels that rise from the wing’s upper surface) to assist with roll. Spoilers on one wing deploy to kill lift on that side, working alongside the inboard ailerons to bank the aircraft smoothly.
Hybrid Surfaces: Flaperons and Elevons
Some aircraft combine the aileron’s roll function with other control surfaces into a single panel. A flaperon acts as both an aileron and a flap. When the pilot commands a turn, the flaperons move in opposite directions like normal ailerons. When the pilot lowers flaps for landing, both flaperons drop symmetrically to increase lift at low speeds. A mixer in the control system blends the two inputs so neither interferes with the other. Flaperons save weight by eliminating the need for separate surfaces, and they appear on aircraft ranging from World War II-era designs to the modern V-22 Osprey tilt-rotor.
Elevons, found on delta-wing and flying-wing aircraft, combine aileron and elevator functions. Moving them in opposite directions rolls the plane; moving them together pitches the nose up or down.
Preventing Flutter
At high speeds, ailerons can vibrate rapidly in a dangerous phenomenon called flutter. Flutter happens when airflow energy feeds into the natural vibration frequency of the control surface, causing oscillations that can tear the aileron, or even the wing, apart in seconds. To prevent this, manufacturers attach small balance weights to the aileron, typically visible as a rod with a weight extending forward from the aileron’s leading edge on smaller planes. These weights shift the aileron’s center of mass closer to its hinge line, making it far less susceptible to aerodynamic vibration. The placement is precise: the goal is to reduce the tendency for the aileron’s mass to twist the wing, not simply to add weight.
From Wing Warping to Ailerons
The earliest powered aircraft, including the Wright Flyer, didn’t have ailerons at all. The Wrights twisted, or “warped,” the outer portions of their flexible wings to control roll. This worked but stressed the wing structure, made the controls heavy, and risked stalling one wing during maneuvers. The aileron concept actually predates powered flight: a British scientist named Matthew Piers Watt Boulton patented an aileron-style control system in 1868, but the patent was forgotten for decades.
Ailerons first appeared on a manned aircraft in 1904, on a French-built glider designed by Robert Esnault-Pelterie. Photos of his design were published in 1905 and widely copied. By 1911, most biplanes had switched to ailerons. By 1916, wing warping had been almost entirely abandoned. Ailerons were simply stronger, more effective, and didn’t weaken the wing the way repeated twisting did.