How Do Flight Airspeed Indicators Function?

Posted on December 11, 2019 Henry Fayol Aviation

Whether an aircraft’s cockpit utilizes a steam gauge or is a modern glass panel, the functionality and principles of the airspeed indicator mostly remains the same. Airspeed indicators are critical to the operation of a flight, enabling pilots to maintain safe operating speeds through speed measurements. In this article, we will discuss how airspeed indicators function and how readings are made.

Indicators are part of the aircraft pitot-static system and gauge airspeed through comparing dynamic and static pressures. Dynamic air pressure is received from the pitot tube of the aircraft, and static pressure comes from a static port which is usually located on the fuselage. Inside of the airspeed indicator case there is a sealed diaphragm which receives both pressures from the pitot tube.

Static pressure is important as atmospheric pressure decreases as the aircraft increases in elevation. Static pressure is also measured both inside the diaphragm and outside, and the two cancel each other out so only the dynamic pressure is left. The diaphragm expands as dynamic pressure increases with acceleration, and this is used to measure climbs in airspeed.

As with any aircraft instrument, reliability can be affected if the components become clogged or iced over. If one of the tubes is blocked, the measurement of dynamic and static air pressure may be inaccurate and lead to the plane either flying faster or slower than what is indicated on the airspeed indicator. There are some remedies and alternatives in place to prevent this, and pilots can either use heat to de-ice areas, or use alternative ports for measuring static pressure. Nevertheless, maintaining optimal and clear instruments is important for accurate measurement of speed.

Of the many aircraft parts, airspeed indicators are extremely important for safe and optimal flights. Airspeeds can help pilots operate in safe speeds in various sections of flight, and often an indicator may display these with a color coded system. They depict various speeds such as flap operating range, normal operating range, cautionary range, and maximum allowed speed. Through accurate readings, pilots can ensure smooth and safe operation during flight.

At ASAP Part Services, owned and operated by ASAP Semiconductor, we can help you find the aircraft flight instrument parts you need, new or obsolete. As a premier supplier of parts for the aerospace, civil aviation, and defense industries, we're always available and ready to help you find all the parts and equipment you need, 24/7x365. For a quick and competitive quote, email us at or call us at +1-714-705-4780.


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