Stall (fluid mechanics)
![Airflow separating from an airfoil at a high angle of attack, as occurs at the stall](/Images/godic/202502/14/Flow_separation2212.jpg")
![](/Images/godic/202502/14/StallFormation.svg2212.png")
![An example of the relationship between angle of attack and lift on a cambered airfoil. The exact relationship is usually measured in a wind tunnel and depends on the airfoil section. The relationship for an aircraft wing depends on the planform and its aspect ratio.](/Images/godic/202502/14/Lift_curve.svg2212.png")
![Flight envelope of a fast airplane.Left edge is the stall speed curve.](/Images/godic/202502/14/AltitudeEnvelopeText2212.GIF")
In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded. The critical angle of attack is typically about 15 degrees, but it may vary significantly depending on the fluid, foil, and Reynolds number.