Flaps should not be extended above which KIAS?

Flaps are critical flight control surfaces that enhance the aerodynamic properties of an aircraft, particularly during take-off and landing. However, extending flaps at excessive airspeeds can lead to structural stress and loss of control due to adverse aerodynamic effects.

The correct limit for extending flaps is set at 85 knots indicated airspeed (KIAS) in many aircraft. This speed is established based on the design limitations of the aircraft’s wing structure and control surfaces. Above this threshold, extending flaps could result in differential lift and drag that might compromise the aircraft's handling characteristics, potentially leading to adverse effects like pitching up or down unexpectedly.

Consequently, pilots are trained to adhere to this limit to ensure the safety of flight operations. Maintaining flap extension within the prescribed airspeed helps preserve the aircraft's performance and control integrity, which is particularly essential during critical phases of flight such as approach and landing.