What is V/DEV on Airbus A320? (Vertical Deviation)

The Airbus A320 is a popular aircraft used by many airlines around the world. With its advanced technology and efficient performance, the A320 has become a staple in the aviation industry. One important aspect of flying the A320 is understanding the concept of Vertical Deviation (V/DEV). V/DEV refers to the difference in altitude between the aircraft’s actual position and its intended altitude. In this article, we will explore what V/DEV is, its significance in aircraft operations, and how it is managed on the Airbus A320.

Understanding Vertical Deviation

Vertical Deviation is a measurement used to determine the vertical position of an aircraft relative to its intended flight level. It is calculated by comparing the aircraft’s barometric altitude, as indicated by the altimeter, to its assigned or selected altitude. The difference between the two altitudes is known as the Vertical Deviation.

For example, if an aircraft is flying at an assigned altitude of 35,000 feet and its altimeter indicates a barometric altitude of 34,500 feet, the Vertical Deviation would be a negative 500 feet. Conversely, if the altimeter indicates a barometric altitude of 35,500 feet, the Vertical Deviation would be a positive 500 feet.

Vertical Deviation can occur due to several factors, including atmospheric conditions, altimeter calibration errors, and aircraft performance. It is essential for pilots to monitor and manage V/DEV to ensure a safe and efficient flight.

Importance of Managing Vertical Deviation

Managing Vertical Deviation is crucial for several reasons. Firstly, maintaining the assigned or selected altitude is necessary to ensure proper separation between aircraft in the same airspace. Air traffic control (ATC) assigns altitudes to aircraft to maintain safe vertical separation, and any deviations from these assigned altitudes can compromise the safety of air traffic.

In addition to safety concerns, managing Vertical Deviation is also vital for maintaining fuel efficiency. Altitude variations can impact an aircraft’s fuel consumption. When flying at levels that differ from the optimal flight level, increased drag or decreased performance may occur, leading to higher fuel consumption.

Furthermore, managing Vertical Deviation is crucial for passenger comfort. Abrupt altitude changes or continuous deviations from the assigned altitude can result in turbulence or discomfort for passengers. By minimizing V/DEV, pilots can provide a smoother and more enjoyable flight experience.

Managing Vertical Deviation on the Airbus A320

The Airbus A320 is equipped with various systems and features that aid pilots in managing Vertical Deviation. One of these features is the Flight Management System (FMS). The FMS allows pilots to input the desired altitude, and it automatically calculates the necessary vertical profile for the aircraft to reach and maintain the selected altitude.

The FMS continuously calculates the Vertical Deviation based on the aircraft’s barometric altitude and the selected altitude. It provides visual and aural alerts to the pilots if the Vertical Deviation exceeds a certain threshold. These alerts prompt the pilots to take corrective actions to minimize the deviation and return to the assigned or selected altitude.

In addition to the FMS, the Airbus A320 is also equipped with an Autopilot System that can assist in managing Vertical Deviation. The Autopilot System can automatically adjust the aircraft’s pitch to maintain the selected altitude, reducing the likelihood of V/DEV and ensuring a smoother flight.

Furthermore, the A320 is equipped with various sensors and instruments that provide accurate altitude information, such as the Air Data Inertial Reference Unit (ADIRU) and the altimeter. These instruments are regularly calibrated and monitored to ensure precise altitude indications, reducing the risk of altitude deviations.

Overall, the Airbus A320’s advanced systems and features play a vital role in managing Vertical Deviation and ensuring a safe and efficient flight. By effectively utilizing these tools, pilots can minimize V/DEV, maintain proper separation, and optimize fuel efficiency.


Vertical Deviation (V/DEV) is an essential concept in aviation, especially when operating the Airbus A320. It represents the difference between an aircraft’s actual altitude and its intended altitude. Managing V/DEV is crucial for safety, fuel efficiency, and passenger comfort. The Airbus A320 is equipped with advanced systems and features, such as the Flight Management System and Autopilot System, to assist pilots in managing Vertical Deviation effectively.

By understanding and actively monitoring V/DEV, pilots can ensure safe vertical separation, optimize fuel consumption, and provide a comfortable flight experience for passengers. The careful management of Vertical Deviation contributes to the overall efficiency and reliability of the Airbus A320 as a popular aircraft in the aviation industry.

External Links

For more information on the Airbus A320 and its systems, you can visit the official Airbus website: https://www.airbus.com/aircraft/passenger-aircraft/a320-family.html

For More: What is OUTR on Airbus A320? (Outer)