We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.
Aviation

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

What Is True Airspeed?

By Paul Scott
Updated: May 23, 2024
Views: 11,336
Share

True airspeed (TAS) is defined as the speed an aircraft travels in relation to the air around it. This is a true indication of the speed of the aircraft which generally differs from that indicated by the instruments in the cockpit. This disparity between true and indicated airspeeds is caused by the air pressures encountered at different altitudes. True airspeed is typically calculated manually with a special slide rule or, in the case of larger aircraft, by a flight management computer. Knowing the true airspeed of an aircraft is critically important for accurate navigation and flight planning.

Air pressure decreases gradually with increases in altitude, a phenomenon which sees the air at sea level being more dense than it is, for example, at 5,000 feet. This causes problems in establishing accurate airspeed readings because most airspeed indicators rely on air pressure for their operation. The readings returned by these instruments are known as indicated airspeed (IAS) and differ from true airspeed values which express the aircraft speed in relation to the air mass surrounding it. Airspeed indicators are calibrated to reflect true airspeed at sea level but will slowly begin to return differing readings as the air pressure decreases inversely with altitude.

For example, an aircraft flying at 100 knots at sea level will have airspeed indicator and TAS values of 100 knots. The same aircraft flying at an indicated 100 knots at 15, 000 feet above sea level will actually be flying at approximately 126 knots. Unfortunately, true airspeed is a critical part of most flight-related calculations associated with aircraft performance and navigation; indicated airspeed readings, therefore, cannot be relied on due to these inherent discrepancies. The necessary TAS readings are typically calculated in one of two ways.

The first is the manual method used by the pilots of most light aircraft. This method requires a special manual air data computer or E6-B as it is also known. This is basically a circular slide rule that allows pilots to calculate various flight envelope related factors. Trainee pilots learn to use a manual flight data computer during their training and it becomes an essential part of the flight bag contents for most, even those who end up flying far more complex and sophisticated planes.

The second method of true airspeed calculation is typically only found on larger, commercial aircraft. In these cases, TAS is calculated by the onboard flight management computer. The calculated readings are then used by the computer to execute flight-plan-related calculations such as fuel burn, wind correction, and navigation. The TAS reading is typically displayed for pilot reference on the aircraft's primary or navigational display units.

Share
WikiMotors is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
Share
https://www.wikimotors.org/what-is-true-airspeed.htm
Copy this link
WikiMotors, in your inbox

Our latest articles, guides, and more, delivered daily.

WikiMotors, in your inbox

Our latest articles, guides, and more, delivered daily.