What is EFOB on Airbus A330? (Estimated Fuel On Board)

The Airbus A330 is a wide-body twin-engine jet airliner that is widely used in the aviation industry. As one of the most popular aircraft in its class, it is important for pilots and operators to have accurate information about the fuel status of the aircraft during flight. This is where the Estimated Fuel On Board (EFOB) comes into play.

EFOB refers to the estimated amount of fuel remaining on board an Airbus A330 aircraft at any given moment during a flight. It provides valuable information to the flight crew in order to ensure the safety, efficiency, and proper management of fuel throughout the journey. In this article, we will dive deeper into the significance of EFOB and how it is calculated.

Calculating Estimated Fuel On Board

The calculation of EFOB takes into account various factors such as fuel consumption, distance to destination, wind conditions, altitude, and aircraft weight. The aircraft’s Flight Management System (FMS) uses these inputs to estimate the fuel remaining on board and continuously updates the EFOB value throughout the flight.

The FMS utilizes a complex algorithm that incorporates real-time data and formulas to determine the EFOB accurately. It considers the fuel flow rate, which is the rate at which fuel is consumed by the engines, and adjusts it based on variables like wind direction and speed. The FMS also takes into account the aircraft’s weight and the distance remaining to be traveled.

Moreover, the FMS considers the altitude of the aircraft. As the altitude increases, the air density decreases, resulting in changes in engine performance and fuel consumption. The FMS takes these changes into account and adjusts the EFOB value accordingly.

The Importance of Estimated Fuel On Board

Knowing the EFOB is crucial for pilots and operators for several reasons. Firstly, it allows the flight crew to monitor and manage the fuel consumption of the aircraft throughout the flight. By constantly monitoring the EFOB and comparing it to the planned fuel usage, the crew can make any necessary adjustments to optimize fuel efficiency and avoid fuel shortages.

Secondly, the EFOB helps in determining whether the aircraft has enough fuel to reach the planned destination or if a diversion may be necessary. In case of unexpected circumstances such as adverse weather conditions or changes in air traffic control, the EFOB provides important information for making decisions regarding flight path changes or alternate landing options.

Additionally, the EFOB is essential for maintaining safety during the flight. In the event of an emergency, having an accurate estimation of the fuel remaining allows the pilot to assess the feasibility of extending the flight or executing emergency operations. It also enables the crew to communicate effectively with air traffic control and other relevant authorities about their fuel situation.

Factors Affecting Estimated Fuel On Board

Several factors can affect the accuracy of the EFOB calculation. One of the major influences is wind conditions. Headwinds can increase fuel consumption, while tailwinds can decrease it. The FMS considers the wind speed and direction to adjust the EFOB value accordingly.

Another factor is the weight of the aircraft. As the aircraft burns fuel, its weight decreases, which affects its fuel consumption rate. The FMS continuously updates the EFOB value to account for the changing weight of the aircraft and ensures accurate estimations.

Furthermore, deviations from the planned flight route can also impact the EFOB. If the aircraft has to deviate from the original flight path due to air traffic control instructions or other reasons, the FMS recalculates the EFOB based on the new route and any additional fuel requirements.

It is important for pilots to communicate any changes in the flight plan to the FMS so that the EFOB can be accurately adjusted. This ensures that the crew has the most up-to-date information regarding the fuel status of the aircraft and can make informed decisions accordingly.


The Estimated Fuel On Board (EFOB) is a critical parameter for the safe and efficient operation of Airbus A330 aircraft. By providing real-time information about the fuel remaining on board, it allows the flight crew to monitor and manage fuel consumption, make informed decisions about flight path changes or diversions, and maintain safety during the flight. The calculation of EFOB takes into account various factors such as fuel consumption, distance to destination, wind conditions, altitude, and aircraft weight. Pilots must work closely with the Flight Management System (FMS) to ensure accurate EFOB estimations and to optimize fuel efficiency throughout the journey.

For More: What is BSCU on Airbus A330? (Brake And Steering Control Unit)