What is ASI on Airbus A320? (Air Speed Indicator)

The Air Speed Indicator (ASI) is an essential instrument in the cockpit of an Airbus A320 aircraft. It provides crucial information about the aircraft’s speed, allowing the pilots to maintain safe and efficient operations during all phases of flight. The ASI measures the dynamic pressure exerted on the aircraft due to its motion through the air, and converts it into an indication of its speed. In this article, we will take a closer look at the Air Speed Indicator on the Airbus A320 and understand its importance in flight operations.

Understanding the Air Speed Indicator

The Air Speed Indicator on the Airbus A320 is a dial-like instrument located in the cockpit. It displays the aircraft’s speed in knots, which is the standard unit of measure for airspeed. The ASI consists of three main components: the pressure sensing system, the sensing element, and the associated mechanical and electrical systems.

The pressure sensing system of the ASI is connected to the aircraft’s pitot-static system, which consists of the pitot tube and static ports. The pitot tube is mounted on the aircraft’s exterior and faces forward, while the static ports are located on the sides of the fuselage. These ports measure the static pressure of the surrounding air, while the pitot tube measures the total pressure (static pressure + dynamic pressure).

The dynamic pressure is the difference between the total pressure measured by the pitot tube and the static pressure measured by the static ports. This dynamic pressure represents the airspeed of the aircraft. The ASI uses this information to display the aircraft’s speed on the dial. The dial markings indicate various speeds such as the indicated airspeed (IAS), the calibrated airspeed (CAS), the true airspeed (TAS), and the Mach number.

The Importance of the Air Speed Indicator

The Air Speed Indicator is a critical instrument for the pilots of the Airbus A320, as it provides essential information for maintaining safe flight operations. Here are some key reasons why the ASI is important:

1. Takeoff and Landing: During takeoff and landing, the pilots rely on the ASI to ensure that the aircraft is operating within safe speed limits. The correct speeds for these phases of flight are specified in the aircraft’s performance charts and vary based on factors such as weight, altitude, and runway conditions. The ASI allows pilots to monitor and adjust the airspeed accordingly to ensure a safe takeoff and landing.

2. Climb and Descent: The ASI is also crucial during climb and descent phases. It provides information about the aircraft’s rate of climb or descent, allowing pilots to maintain the desired vertical speed. The ASI helps the pilots to control the aircraft’s performance and ensure a smooth and efficient climb or descent.

3. Cruise Speed: The ASI is used to maintain the desired cruise speed during the en-route phase of flight. The pilots set the target airspeed based on factors such as fuel efficiency, aircraft limitations, and air traffic control instructions. The ASI allows them to monitor and adjust the airspeed as necessary to optimize the flight’s performance.

4. Airspeed Limitations: The ASI displays the aircraft’s maximum and minimum operating speeds. These speeds are crucial for the pilots to prevent any exceedance of the aircraft’s structural limits. The ASI provides visual cues to the pilots, allowing them to take appropriate corrective actions if the airspeed approaches these limits.


The Air Speed Indicator plays a vital role in the safe and efficient operation of the Airbus A320 aircraft. It provides pilots with real-time information about the aircraft’s speed, allowing them to make informed decisions during each phase of flight. With accurate airspeed indications, pilots can ensure the aircraft operates within safe limits, optimize fuel efficiency, and maintain smooth and stable flight conditions. Understanding the Air Speed Indicator and its significance is essential for both pilots and aviation enthusiasts alike. So next time you’re on an Airbus A320, take a moment to appreciate the critical role the ASI plays in keeping you safe in the air.

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