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Performance and Limitations - QT

Updated: Apr 20, 2021

Lesson Quicktakes cover the items that should be memorized from each of the wifiCFI Lessons. They do not cover all of the lesson details in-depth.


  • Indicated Altitude = The Altitude read off the altimeter in flight.

  • True Altitude = The Altitude above mean sea level (MSL).

  • Absolute Altitude = The Altitude above ground level (AGL).

  • Pressure Altitude = The Altitude above the Standard Datum Plane (29.92).

  • Density Altitude = The Altitude at which the aircraft will perform. Regardless of actual altitude.


  • Hotter Temperatures = Higher Density Altitude (worse aircraft performance).

  • Cooler Temperatures = Lower Density Altitude (better aircraft performance).

  • Increased Humidity = Decreased Aircraft Performance.

  • Decreased Humidity = Increased Aircraft Performance.

  • Higher Pressure = Increased Aircraft Performance.

  • Lower Pressure = Decreased Aircraft Performance.


  • Indicated Airspeed = The Airspeed read off the Airspeed Indicator.

  • Used for: Speed limits, ATC speed restriction, aircraft V-speeds.

  • Calibrated Airspeed = Indicated Airspeed corrected for Pitot Tube Installation.

  • Used to: Calculate True Airspeed.

  • True Airspeed = Speed of the Aircraft relative to the airmass in which it is flying.

  • Used to: Calculate Groundspeed.

  • Groundspeed = The speed of the Aircraft over the surface of the Earth.

  • Used for: Time and distance calculations.


  • Vso = power off stalling speed in the landing configuration.

  • Vs1 = power off stalling speed in a specified configuration.

  • Vy = best rate of climb speed - Maximum increase in altitude per unit of time.

  • Vx = best angle of climb speed - Maximum increase in altitude per horizontal distance unit.

  • Vle = max speed the aircraft can be operated with the landing gear extended.

  • Vlo = max speed at which the landing gear can be safely extended or retracted.

  • Vfe = max permissable speed with the wing flaps extended to a specified degree.

  • Va = design maneuvering speed.

  • Vno = maximum structural cruising speed.

  • Vne = the speed that should never be exceeded in flight.

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