Airspeed Indicator Markings

[Ref. Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25B Page 8-9, 8-10]

To enable pilots to determine certain airspeed limitations at a glance, airspeed indicator (ASI) has a standard color-coded marking .

In single-engine general aircraft’s analog ASI, there are 4-color areas:

  1. White arc
    • “Flap operating range”
  2. Green arc
    • normal operating range
  3. Yellow arc
    • “caution range”
    • operates within this range only in smooth air
  4. Red line
    • “Never exceed speed”
    • Vne

 

Rightly, different specific airspeed may be defined with specific significance in operations:

  1. Lower limit of white arc : Vs0
    • power-off stalling speed in landing config (gear and flaps down)
  2. Lower limit of green arc: Vs1
    • power-off stalling speed in clean config
  3. Upper limit of white arc: Vfe
    • max. speed with the flaps extended
  4. Upper limit of green arc: Vno (≠ Va)
    • max. structural cruising speed

 

In addition, some speed has special significance but they are not specially marked on ASI:

  1. Va – Design Maneuvering Speed
  2. Vle – Landing gear extended speed
  3. Vlo – Landing gear operating speed
  4. Vx – Angle of climb
  5. Vy – rate of climb
  6. Vcc – cruise climb

 

Read More –

[Ref The turbine pilot’s flight manual Review (ISBN:9781619540293)]

Pilots should know well about their plane, including different limitations, which are set to ensure the plane work under safe and efficient conditions. However, this chapter also aims to point out those special or dedicate to turbine aircraft.

    • there is no redline on speed indicator of turbine aircraft
    • Use “maximum operating limit speed” (e.g Vmo,Mmo) rather than “Never exceed speed, Vne” in piston engine
      • Vmo is a structural limit designed to prevent airframe damage from excess dynamic pressure.
      • Mmo is a limit designed to prevent aircraft from shock wave damage as the aircraft approaches the speed of sound.
      • Notes:
        Vmo and Mmo are not fixed and they are vary with altitude;
        Generally speaking, at lower altitudes, Vmo is the “maximum operating limit speed” (so Mmo is the “maximum operating limit speed” at higher altitudes)
    • Turbulent air penetration speed (Vb), is a limit on turbine engine, which offers maximum-value gust protection (Maneuvering speed, Va, is still existing like piston engine)

 

 

 

 

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