Flight Redemptions

What is ICO in Aviation? (Idle Cut Off)

Updated: February 29, 2024

Understanding Idle Cut-Off (ICO) in Aviation

Aviation is a complex and fascinating industry with its own set of technical terms and acronyms that can sometimes be confusing to those unfamiliar with the field. One such term is idle cut-off (ICO), which refers to a specific action performed by pilots or aircraft systems during certain phases of flight. In this article, we will explore the concept of idle cut-off, its significance in aviation, and how it affects aircraft performance and safety.

The Role of Idle Cut-Off in Aircraft Operations

Idle cut-off (ICO) is a crucial procedure in aviation that involves shutting down one or more engines of an aircraft, typically during ground operations or in specific flight conditions. The purpose of performing an idle cut-off is to conserve fuel, reduce emissions, and ensure the safe operation of the aircraft.

During ground operations, such as taxiing or waiting at the gate, pilots may engage idle cut-off to minimize fuel consumption while the aircraft is stationary. By shutting down engines that are not required for immediate operation, airlines can significantly reduce their fuel expenses and environmental impact. Idle cut-off also helps to mitigate the risk of engine-related incidents, such as fires or other malfunctions, by reducing the time engines are running without a specific operational purpose.

While idle cut-off during ground operations is relatively common, the procedure becomes even more critical in specific flight conditions. For instance, during an in-flight emergency or when an engine fails, pilots may need to perform an idle cut-off on the affected engine to prevent further damage or potential hazards. Shutting down a malfunctioning engine can help prevent the spread of fire, limit vibrations, and maintain the stability and control of the aircraft. It is worth noting that this procedure requires a high level of skill and training on the part of pilots, as they must carefully assess the situation and make the appropriate decision to ensure the safety of all onboard.

Factors Influencing Idle Cut-Off Decisions

When it comes to determining whether an idle cut-off is necessary, pilots consider various factors and rely on their knowledge, experience, and standard operating procedures. Some of the key factors that influence the decision to perform an idle cut-off include:

Engine performance and indications: If an engine exhibits abnormal behavior, such as excessive vibrations, loss of power, or unusual noises, pilots may opt to shut it down using idle cut-off.
Fire or smoke indications: In the event of a fire or smoke emanating from an engine, pilots may perform an idle cut-off to prevent the spread of flames or further damage.
Flight phase: The decision to engage idle cut-off may vary depending on the phase of flight. For example, during takeoff or landing, pilots are unlikely to perform an idle cut-off unless absolutely necessary, as the operation of all engines is crucial for a safe and controlled maneuver.
Flight conditions: Adverse weather conditions, such as severe turbulence or icing, may prompt pilots to shut down specific engines using idle cut-off to ensure the safety and stability of the aircraft.
Emergency procedures: In the event of an emergency, pilots follow specific procedures outlined in their aircraft's emergency checklist. These procedures may include the use of idle cut-off to address critical issues and minimize risks.

It is essential to note that idle cut-off is not always the recommended course of action, and pilots must carefully evaluate the situation before initiating the procedure. In some cases, alternative actions, such as reducing engine power or adjusting engine parameters, may be more appropriate to address the specific issue at hand.


Idle cut-off (ICO) plays a crucial role in aviation, allowing pilots to conserve fuel, reduce emissions, and ensure the safe operation of aircraft. Whether it's for ground operations or managing in-flight emergencies, the decision to perform an idle cut-off requires careful consideration of various factors, including engine performance, indications of fire or smoke, flight phase, flight conditions, and adherence to emergency procedures. By understanding and effectively implementing idle cut-off procedures, pilots contribute to the overall efficiency, safety, and sustainability of aviation operations.

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