What is VMC Roll? - Engine Failure on Takeoff

The term "VMC Roll" is typically associated with aviation and refers to the control and handling of an aircraft during a situation known as "engine failure on takeoff" or "engine failure after takeoff." VMC stands for "Velocity Minimum Control." This is a critical airspeed that represents the minimum speed at which an aircraft can maintain controlled flight in the event of an engine failure, typically during takeoff.

1. VMC Speed: VMC is the airspeed at which an aircraft can still maintain controlled flight with one engine inoperative and the other engine at full power. Below this speed, the aircraft may not have sufficient control authority to counteract the asymmetric thrust (the thrust imbalance between the working engine and the failed engine).
2. Roll: The "roll" in VMC Roll refers to the aircraft's roll axis, which is its ability to control and maintain level flight without rolling uncontrollably due to the engine failure.

When an aircraft experiences an engine failure during takeoff or immediately after takeoff, it can be a critical situation. If the aircraft's airspeed falls below VMC, the pilot may have limited control over the aircraft's heading, altitude, and roll. It becomes challenging to maintain wings level and prevent a dangerous roll or loss of control.

Pilots are trained to recognize the importance of VMC and to respond to engine failures during takeoff by following specific procedures. These procedures may involve reducing power on the operating engine, adjusting control surfaces, and maintaining a minimum airspeed to ensure the aircraft remains in a controlled and safe flight regime.

The specific VMC speed for an aircraft is determined during its certification process and can vary from one type of aircraft to another, depending on factors like aircraft design, engine performance, and other aerodynamic characteristics. It's a critical parameter that pilots must be aware of to safely handle engine failures during takeoff and climb. Failure to maintain control above VMC speed can result in a loss of control and potentially lead to a hazardous situation, such as a roll or a stall.

Some sources for further information: An investigation of piloting strategies for engine failures during takeoff from offshore platforms / The feasibility of turnback from a low altitude engine failure during the takeoff climb-out phase