Aircraft Flight instruments | Six Basic Flight Instruments

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Basic Flight Instruments

Electronic transducers, as well as electronic displays and indications, are used in modern aeroplanes. In what has become known as a "glass cockpit," cathode ray tubes (CRT) and liquid crystal displays (LCD) are increasingly employed to display this information. Modern passenger aeroplanes typically feature many of these displays, including primary flight data displays and multi-function displays that can be customized to display a variety of data.

These basic flight instruments are required to display information concerning aircraft.  Old or modern aircraft both have these basic flight instruments. However, the display may be conventional or electronic.

Six Basic Flight Instrument

The instruments that show the aircraft's position and attitude are among the flying instruments installed on any aircraft.

• Heading

• Altitude

• Airspeed

• Rate of turn

• Rate of climb (or descent)

• Attitude (relative to the horizon).

These basic flight instruments are required to show information regarding aircraft behavior. These basic flight instruments are found in both old and new aircraft, although the display may be conventional or electronic. The aircraft's pitot-static system feeds several of these instruments & they are also commonly referred to as Air Data Instruments.


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Altimeter indicates the aircraft’s height (in feet or meters) above a mean sea level by measuring the local air pressure. To provide accurate readings the instrument has an adjustable knob for adjusting local barometric pressure. In large aircraft a second standby altimeter is also provided.

Attitude indicator or Artificial Horizon

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Attitude Indicator

Attitude Indicator or Artificial Horizon displays the aircraft’s attitude relative to the earth horizon. From this instrument the pilot can determine whether the wings are level and if the aircraft nose is above or below the horizon. This is a primary instrument for Instrument Flight Rule (IFR) and is also useful in conditions of poor visibility. Pilot must trained to use other instruments in combination with this instrument in case of  power fail.

Airspeed indicator

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Airspeed Indicator

Airspeed Indicator displays the speed of the aircraft (in knots) relative to the atmospheric surrounding air. The instrument compares the ram air pressure entering in the aircraft’s pitot tube with the combination of static pressure. The indicated airspeed shows in aircraft must be corrected for air density, which varies with altitude, temperature and humidity.

Magnetic compass

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Magnetic compass

Magnetic compass indicates the aircraft’s heading relative to earth magnetic north. However, due to the inclination of the earth’s magnetic field, the magnetic compass can be unreliable when turning, climbing, descending, or accelerating. Because of this the HSI is used. For accurate navigation of aircraft, it is necessary to correct the direction indicated in order to obtain the direction of true north or south.

Horizontal Situation Indicator (HSI)

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Horizontal Situation Indicator (HSI) 

The horizontal situation indicator (HSI) shows the aircraft's position and direction in a plan view. The HSI gets its data from the compass and radio navigation equipment (VOR), which uses ground stations to offer accurate bearings. The VOR receiver is commonly incorporated with the VHF communication radio equipment in light aircraft, while a separate VOR receiver is installed in large aircraft.

Turn and Bank Indicator or Turn Coordinator

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Turn and Bank Indicator or Turn Coordinator

Indicates the turn's direction and rate of turn both. An inclinometer positioned internally shows the ‘quality' of the turn, i.e. whether the turn is properly coordinated, as opposed to an uncoordinated turn, which would result in the aircraft slipping or skidding. The turn and bank indicator has been replaced in modern aircraft by the turn coordinator, which shows the rate and direction of roll when the aircraft is rolling, as well as the rate and direction of turn when the aircraft is not rolling.

Vertical Speed Indicator

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Vertical Speed Indicator

Vertical speed Indicator (VSI) Indicates rate of climb or descent (in feet per minute or metres per second) by sensing changes in air pressure.

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