What is the maximum speed when the windows are open?

What is the maximum speed when the windows are open?

• A. 149 knots
• B. 104 knots
• C. 95 knots
• D. 70-80 knots

Answer: (A)

Opening a window changes the aerodynamic loads on the opening and its frame. As airspeed increases, the dynamic pressure pressing on the window grows with the square of the speed, so the forces on the window latch, frame, and surrounding structure rise. To keep those loads within what the hardware was designed to safely handle, a maximum indicated airspeed is specified for flying with a window open. For this aircraft, that limit is about 149 knots, which gives a safety margin for gusts and minor sealing issues. Flying faster than this increases the risk of window failure or abnormal handling. The other speeds would either be unnecessarily restrictive or not align with the intended safety margin.

Opening a window changes the aerodynamic loads on the opening and its frame. As airspeed increases, the dynamic pressure pressing on the window grows with the square of the speed, so the forces on the window latch, frame, and surrounding structure rise. To keep those loads within what the hardware was designed to safely handle, a maximum indicated airspeed is specified for flying with a window open. For this aircraft, that limit is about 149 knots, which gives a safety margin for gusts and minor sealing issues. Flying faster than this increases the risk of window failure or abnormal handling. The other speeds would either be unnecessarily restrictive or not align with the intended safety margin.