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A Short Guide to Aircraft Instrument Systems

Beginning with the stopwatch, anemometer, and tachometer on the Wright Flyer, aircraft instruments have gone through many significant changes to get to where we are today. A quick look at the modern “glass cockpit” shows how great of an impact that improving technology has had on the systems we use to monitor altitude, air pressure, wind speed, and more. However, at their core, many of these instruments function based on the same working principles as their earliest versions. In this blog, we present some insight into the various types of aircraft instruments you will find in your cockpit, along with some basic information about repair and replacement options for each.

Types of Aircraft Instrument

  • Pressure Instruments: All modern aircraft, whether they have digital or analog instruments, share the same basic pitot-static system. Made up of a network of pipes, sensors, and instruments that measure air pressure, the pitot-static system is used to measure the aircraft’s airspeed, altitude, and vertical speed. More specifically, these readings are provided through instruments known as the altimeter, airspeed indicator, and vertical speed indicator. These pressure flight instruments operate off of the pitot-static system, and they are self-powered and extremely sensitive diaphragm-type instruments relying only on variations in pressure to operate. Therefore, as a system used to measure minute changes in pressure, any leaks, disturbed air, or partial blockages in the lines serving instruments like the altimeter, airspeed, and vertical speed indicator will affect accuracy. As such, it is incredibly important to be careful with these instruments while also conducting regular evaluations and maintenance with the help of trusted professionals.

  • Vacuum Instruments: Vacuum-operated instruments are common on aircraft, and they are typically very reliable as a result of their simplicity. In most light aircraft, the vacuum system consists of an engine-driven vacuum pump, relief valve, suction gauge, and inlet filter. All these components are combined with a network of hoses and collectively work to drive the gyroscopic instruments mounted on a cockpit panel. The vacuum system is relatively simple in its design, but its functionality can become impacted when basic maintenance requirements are neglected. Without an effective vacuum pump, the altitude indicator, directional gyro, and other instruments will malfunction. As such, it is critical to follow manufacturer specifications for conducting maintenance and replacing components when necessary.

  • Electric Instruments: The 21st century has seen a major rise in the use of electric instruments on aircraft, especially those contributing to the screen-filled flight deck. Just like any other instrument on board, each electric instrument assembly  must be regularly evaluated to ensure that they work properly. These instruments include the electrical tachometer, fuel quantity sender, and others. Many of these devices are self-powered to safeguard them in case of electrical failure elsewhere on the plane. Even so, it is still important to regularly check the wiring and connections for issues as anything electrical is subject to the effects of vibration, corrosion, and broken connections. Also note that individual components of an electrical system are in most cases not interchangeable, so it is vital to pay attention to the specific type and brand of instrument your project requires.


As an aircraft owner or operator, it is very important that you properly maintain your aircraft instruments, as well as seek repairs or replacements at the first sign of an issue. Moreover, if you require a replacement part for your assembly, it is crucial to source components from credible manufacturers who can assure the airworthiness of their offerings. At Distribution 3Sixty, we are a sourcing partner that takes care of this essential, but often time-consuming, process by vetting all our manufacturers before adding their items to our catalog. Regardless of your operational needs and deadlines, you can rely on us to find a solution that is fit to your requirements. Begin exploring our catalog of available parts today and find quality-tested items that you can depend on for your operations!


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