What configuration is observed when determining Vmc?

When determining Vmc, or minimum control speed, the correct configuration is flaps up and gear up. This configuration is standard because it represents the cleanest state of the aircraft, which is essential when evaluating how the aircraft behaves in a single-engine failure scenario.

In the flaps-up and gear-up configuration, the aircraft's aerodynamics are optimized for flight, which helps in accurately assessing the control effectiveness when one engine fails. At Vmc, the aircraft is on the verge of uncontrollability due to asymmetric thrust, and having the gear and flaps in the retracted position reduces drag and helps maintain a more predictable performance profile. This allows pilots to understand the critical speed at which they can still maintain control with one engine inoperative.

Other configurations, such as having flaps down or gear down, can alter the stall characteristics and drag on the aircraft, resulting in a higher Vmc than would be experienced in the clean configuration. This makes it crucial for pilots to know Vmc under the appropriate clean condition to ensure pilot proficiency and safety.