Angle of Attack is used to define the angle between the wing chord  line and the flight path—not the ground. During landing, an aircraft may have a level attitude, but a high angle of attack, because the flight path is downward and the approaching wind is parallel to the flight path. During climb, the airplane can be in a nose-high attitude, but at a low angle of attack.

Angle of Attack is used to define the angle between the wing chord  line and the flight path. This is not to be confused with the relation of the aircraft to the Earth’s surface. This is called the attitude and is seldom, if ever, the same as the angle of attack.

    When the angle is small, the aircraft is said to be at a low angle of attack. When the angle is large, the aircraft is said to be at a high angle of attack.

    Two variables can change the amount of lift generated by a wing in a given configuration.
• The speed of air flowing over the airfoil.
• The angle of attack.
    An increase in speed or the angle of attack will increase both lift and drag. In level flight, lift must equal the weight of the aircraft. If an aircraft weighs 2,000 lbs., the wing must generate 2,000 lbs. of lift. The speed and angle of attack are interchangeable to a point—therefore, for every airspeed, there is a corresponding angle of attack that will produce the same amount of lift.

In order for a wing to produce lift, the air flowing past an aircraft, must be aligned to the airfoil in order to provide a smooth airflow. As a wing increases its angle of attack, airflow can no longer flow smoothly over the wing and eddies or burbles will form, causing the wing to approach its stall speed. When a wing finally stalls, it will no longer produce lift and with weight unopposed by lift, the aircraft will drop towards the ground. With sufficient altitude, stall recovery can be obtained by decreasing the angle of attack.


Angle of Attack is the angle between the wing chord line and the flight path.

An airplane can be stalled at any attitude and at any airspeed such as pulling out of a dive too abruptly or if the airplane is in a steep turn at a high angle of attack, even though the airspeed is high. During dives or turns, centrifugal force will increase load factors and if excessive, this will cause the wing to stall.

    The angle of attack should not be confused with the angle of incidence. The angle of incidence is the angle formed by the wing chord line and the aircraft longitudinal axis. Refer to the page on relative wind for comparison.

An airfoil is a device which gets a useful reaction from air moving over its surface. When an airfoil is moved through the air, it is capable of producing lift. Wings, horizontal tail surfaces, vertical tails surfaces, and propellers are all examples of airfoils.

Generally the wing of small aircraft will look like the cross-section of the figure above. The forward part of an airfoil is rounded and is called the leading edge. The aft part is narrow and tapered and is called the trailing edge. A reference line often used in discussing airfoils is the chord, an imaginary straight line joining the extremities of the leading and trailing edges.

Bernoulli's Principle: To understand how lift is produced, we must examine a phenomenon discovered many years ago by the scientist Bernoulli and later called Bernoulli's Principle: The pressure of a fluid (liquid or gas) decreases at points where the speed of the fluid increases. In other words, Bernoulli found that within the same fluid, in this case air, high speed flow is associated with low pressure, and low speed flow with high pressure. This principle was first used to explain changes in the pressure of fluid flowing within a pipe whose cross-sectional area varied. In the wide section of the gradually narrowing pipe, the fluid moves at low speed, producing high pressure. As the pipe narrows it must contain the same amount of fluid.In this narrow section, the fluid moves at high speed, producing low pressure.

An important application of this phenomenon is made in giving lift to the wing of an airplane, an airfoil. The airfoil is designed to increase the velocity of the airflow above its surface, thereby decreasing pressure above the airfoil.Simultaneously, the impact of the air on the lower surface of the airfoil increases the pressure below. This combination of pressure decrease above and increase below produces lift.Probably you have held your flattened hand out of the window of a moving automobile. As you inclined your hand to the wind, the force of air pushed against it forcing your hand to rise. The airfoil (in this case, your hand) was deflecting the wind
which, in turn, created an equal and opposite dynamic pressure on the lower surface of the airfoil, forcing it up and back.The upward component of this force is lift; the backward component is drag.