What is the significance of the white arc on an airspeed indicator?

The white arc on an airspeed indicator is significant because it shows the flap operating range. This range defines the speeds at which the aircraft can safely use flaps during various phases of flight, particularly during approach and landing. When the flaps are extended, the aircraft can operate safely in this range, which provides additional lift at lower speeds, thus enabling better control while flying slower and during landings.

Maintaining operation within the white arc is essential for avoiding unintentional stalls or loss of control during critical phases of flight. Each aircraft has specific speeds that are marked within this white arc, indicating the minimum and maximum speeds for flap extension and use, ensuring pilots understand their limitations when manipulating flaps.

Understanding this marking is vital for flight safety, as it helps pilots avoid flying too slowly with flaps extended, which could lead to a stall.