Flight Instruments Vocabulary

Flashcards reviewing key terms and definitions related to flight instruments and systems.

Pitot-Static System

A combined system that utilizes static air pressure and dynamic pressure to operate the airspeed indicator (ASI), altimeter, and vertical speed indicator (VSI).

Static Pressure

Also known as ambient pressure, it's the barometric pressure in the local area, present whether the aircraft is moving or at rest.

Dynamic Pressure

Pressure present only when an aircraft is in motion; generated by the aircraft's movement through the air or by wind.

Altimeter

Instrument that measures the height of an aircraft above a given pressure level.

Aneroid Wafer

Sealed wafer inside the altimeter that is evacuated to an internal pressure of 29.92 inches of mercury and expands/contracts with changes in static pressure.

Indicated Altitude

The altitude read directly from the altimeter when it is set to the current altimeter setting.

True Altitude

The vertical distance of the aircraft above sea level (MSL); actual altitude.

Absolute Altitude

The vertical distance of an aircraft above the terrain (AGL).

Pressure Altitude

The altitude indicated when the altimeter setting window is adjusted to 29.92 "Hg; altitude above the standard datum plane.

Density Altitude

Pressure altitude corrected for variations from standard temperature; directly related to aircraft performance.

Vertical Speed Indicator (VSI)

Indicates whether the aircraft is climbing, descending, or in level flight, and the rate of climb or descent in feet per minute (fpm).

Instantaneous Vertical Speed Indicator (IVSI)

VSI that incorporates accelerometers to compensate for lag.

Airspeed Indicator (ASI)

Sensitive, differential pressure gauge that measures and indicates the difference between pitot (impact/dynamic pressure) and static pressure.

Indicated Airspeed (IAS)

Direct instrument reading obtained from the ASI, uncorrected for variations in atmospheric density, installation error, or instrument error.

Calibrated Airspeed (CAS)

IAS corrected for installation error and instrument error.

True Airspeed (TAS)

CAS corrected for altitude and nonstandard temperature.

Groundspeed (GS)

Actual speed of the airplane over the ground; TAS adjusted for wind.

White Arc (ASI)

Flap operating range; lower limit is full flap stall speed, upper limit is maximum flap speed.

Green Arc (ASI)

Normal operating range of the aircraft.

Yellow Arc (ASI)

Caution range; fly within this range only in smooth air and with caution.

Red Line (ASI)

Never exceed speed (VNE); operating above this speed is prohibited.

Design Maneuvering Speed (VA)

Maximum speed at which the structural design's limit load can be imposed without causing structural damage.

Best Angle-of-Climb Speed (VX)

Airspeed at which an aircraft gains the greatest amount of altitude in a given distance.

Best Rate-of-Climb Speed (VY)

Airspeed that provides the most altitude gain in a given period.

Electronic Flight Display (EFD)

A display that combines all flight instruments onto a single screen.

Attitude Heading and Reference System (AHRS)

An electronic system that provides attitude information to the PFD.

Rigidity in Space

The principle that a gyroscope remains in fixed position in the plane in which it is spinning.

Precession

The tilting or turning of a gyro in response to a deflective force.

Turn-and-Slip Indicator

Turn indicator that shows only the rate of turn in degrees per second.

Turn Coordinator

Turn indicator mounted at an angle that shows roll rate and rate of turn.

Inclinometer

Instrument consisting of a liquid-filled curved tube with a ball inside, used to depict aircraft yaw.

Magnetic Compass

Basic instrument indicating direction.

Variation

The difference between true and magnetic directions.

Deviation

Compass error due to magnetic fields in the aircraft.

Angle of Attack (AOA) Indicator

Gives the pilot better situational awareness pertaining to the aerodynamic health of the airfoil.