<P> A redline mark indicates V , or velocity ( never exceed ) . This is the maximum demonstrated safe airspeed that the aircraft must not exceed under any circumstances . The red line is preceded by a yellow band which is the caution area , which runs from V ( maximum structural cruise speed ) to V. A green band runs from V to V. V is the stall speed with flaps and landing gear retracted . A white band runs from V to V. V is the stall speed with flaps extended , and V is the highest speed at which flaps can be extended . Airspeed indicators in multi-engine aircraft show a short radial red line near to the bottom of green arc for V , the minimum indicated airspeed at which the aircraft can be controlled with the critical engine inoperative and a blue line for V , the speed for best rate of climb with the critical engine inoperative . </P>
what does the lower limit of the green arc on an airspeed indicator represent
the minimum indicated airspeed at which the aircraft can be controlled with the critical engine inoperative