What is A/F in Aviation? (Autofeather)

Autofeather, often abbreviated as A/F, is a crucial safety feature in aviation that helps to mitigate risks and improve the performance of aircraft. It is a system that automatically adjusts the position of an aircraft’s propellers in response to specific conditions, preventing excessive drag, improving the overall aerodynamic efficiency, and aiding in maintaining control during critical phases of flight. Autofeather systems have been incorporated into various types of aircraft, ranging from small general aviation airplanes to larger commercial jets.

In this article, we will delve into the details of Autofeather, exploring its functionality, benefits, and its significance in aviation safety.

How Autofeather Works

The Autofeather system is designed to detect anomalies in the aircraft’s engine or power loss. When specific conditions and parameters are met, the system engages, immediately adjusting the propeller pitch to the feather position. Feathering refers to the action of changing the angle of the propeller blades so that they are lined up with the airflow and cause minimal drag.

Autofeather relies on sensors that monitor engine power, torque, and airspeed. If the system detects a significant decrease in engine power or detects an engine failure, it signals the propeller control system to initiate autofeather. This action automatically feathers the propeller blades, reducing drag and allowing the aircraft to maintain better control and maneuverability in the event of an engine failure.

The Autofeather system is most commonly used during takeoff and landing, which are considered the most critical phases of flight. During takeoff, should an engine fail, the autofeather system immediately feathers the failed engine’s propeller, reducing drag and minimizing the asymmetrical thrust that could cause the aircraft to veer off the runway. This enhances the pilot’s ability to control the aircraft and make a safe landing or execute a go-around if necessary.

Similarly, during landing, the autofeather system ensures that in the event of an engine failure, the aircraft’s handling remains optimal. By automatically feathering the propeller of the affected engine, the aircraft’s drag is reduced, helping the pilot maintain control and execute a safe landing.

The autofeather system is generally deactivated during cruise flight or when the aircraft is above a specified altitude. This avoids unnecessary pitch adjustments of the propellers and allows for a smoother and more fuel-efficient operation.

The Importance of Autofeather in Aviation Safety

Autofeather plays a critical role in aviation safety, particularly during takeoff and landing, where engine failures or power losses pose significant risks. By automatically feathering the propeller of a failed engine, the system helps to maintain the aircraft’s balance and control, minimizing the likelihood of a catastrophic event. According to the Federal Aviation Administration (FAA), the Autofeather system contributes to the safe operation of aircraft by providing pilots with the necessary tools to handle emergencies effectively.

During takeoff, engine failures can occur due to various reasons, including mechanical failures, fuel system issues, or adverse weather conditions. The immediate feathering of the failed engine’s propeller reduces drag and enhances the aircraft’s control, making it easier for the pilot to manage the situation and make informed decisions.

Additionally, Autofeather minimizes the risks of drifting off the runway during takeoff. In the event of an engine failure, the uneven thrust generated by the remaining engine can cause the aircraft to veer off course if not promptly corrected. By automatically feathering the propeller, the system helps the pilot maintain directional control, reducing the chances of runway excursions and enhancing passenger safety.

During landing, engine failures present similar risks. A failed engine can lead to a loss of control or impair the aircraft’s ability to maintain a stable approach and touchdown. The autofeather system actively mitigates these risks by feathering the affected propeller, reducing drag, and maintaining the aircraft’s stability and control. This allows for safer landings and provides pilots with an additional layer of support during critical avionics malfunctions or emergencies.

Overall, the inclusion of the Autofeather system in aircraft greatly enhances the safety and reliability of flight operations, reducing the likelihood of accidents caused by engine failures and power losses.


Autofeather, or A/F, is a vital safety feature in aviation that automatically adjusts the propeller pitch to the feather position in the event of an engine failure or power loss. By reducing drag and aiding in maintaining control, the Autofeather system improves the safety and performance of aircraft during critical flight phases such as takeoff and landing. Its contribution to aviation safety cannot be overstated, providing pilots with essential tools to handle emergencies effectively and mitigate potential risks.

As technology advances, new safety features continue to be developed to make aviation even safer. Autofeather remains a key component in these advancements, and its significance in enhancing the safety and reliability of aircraft operations will continue to be recognized and appreciated.

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