Commercial Pilot License (CPL) Practice Exam 2026 - Free Commercial Pilot License Practice Questions and Study Guide

The critical engine is identified primarily because its failure has the most significant impact on an aircraft's handling and performance. This is particularly crucial in multi-engine aircraft, where the balance and control depend heavily on the functioning of all engines. If the critical engine experiences a failure, it can create an asymmetrical thrust situation, leading to adverse yaw and the need for additional pilot inputs to maintain control. The aircraft may also experience increased drag on the side of the failed engine, which further complicates handling and can compromise the aircraft's performance, especially during critical phases of flight such as takeoff and climb.

In most conventional multi-engine configurations, the critical engine is typically the engine whose loss results in the most pronounced deviation from controlled flight, making it essential for pilots to understand how to recognize and react to this kind of failure effectively. Understanding the mechanics behind this helps pilots maintain safer operations and manage emergencies with greater skill.