Extending flaps creates a new airfoil shape with increased camber and increased lifting ability, allowing the wings to support the same load at a lower speed. Therefore, the airspeed can decrease to a lower value before the stall angle is reached. This is the main advantage of flaps—safe flight at lower speeds which is useful for takeoffs, landings on short fields, low speed searches, and lower nose attitudes for better visibility.

It is conceivable that the system controlling one flap could fail, allowing one flap to quickly streamline causing an asymmetrical lift condition that would roll the aircraft unexpectedly. For this reason, some pilots have developed a personal policy of planning flap extensions and retractions to occur only when wings are level. Such planning is easy to do and is only a small part of each experienced aviator's risk management system. One should never retract the flaps to correct for undershooting since that will suddenly decrease the lift and cause the airplane to sink even more rapidly.