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Airspeed Indicator (ASI) – Other Airspeed Limitations

in Flight Instruments

Some important airspeed limitations are not marked on the face of the ASI, but are found on placards and in the AFM/POH. These airspeeds include:


  • Design maneuvering speed (VA)—the maximum speed at which the structural design’s limit load can be imposed (either by gusts or full deflection of the control surfaces) without causing structural damage. It is important to consider weight when referencing this speed. For example, VA may be 100 knots when an airplane is heavily loaded, but only 90 knots when the load is light.
  • Landing gear operating speed (VLO)—the maximum speed for extending or retracting the landing gear if flying an aircraft with retractable landing gear.
  • Landing gear extended speed (VLE)—the maximum speed at which an aircraft can be safely flown with the landing gear extended.
  • Best angle-of-climb speed (VX)—the airspeed at which an aircraft gains the greatest amount of altitude in a given distance. It is used during a short-field takeoff to clear an obstacle.
  • Best rate-of-climb speed (VY)—the airspeed that provides the most altitude gain in a given period of time.
  • Single-engine best rate-of-climb (VYSE)—the best rate-of-climb or minimum rate-of-sink in a light twin-engine aircraft with one engine inoperative. It is marked on the ASI with a blue line. VYSE is commonly referred to as “Blue Line.”
  • Minimum control speed (VMC)—the minimum flight speed at which a light, twin-engine aircraft can be satisfactorily controlled when an engine suddenly becomes inoperative and the remaining engine is at takeoff power.

51DPcJTcMwL._SX381_BO1,204,203,200_Learn more about all of your flight instruments with the Instrument Flying Handbook. This is the FAA’s primary pilot resource for instrument flight rules (IFR) covering everything pertinent to operating an aircraft in instrument meteorological conditions (IMC) or without reference to outside visuals, relying solely on the information gleaned from the cockpit.

 

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