In which operation phase is a rich mixture particularly needed?

A rich mixture is particularly needed during the takeoff phase of flight because it ensures that the engine receives an adequate fuel-to-air ratio necessary for maximum power and performance. During takeoff, an aircraft must generate significant thrust to overcome gravity and achieve the required climb rate. A rich mixture, which contains more fuel relative to air, can enhance engine performance, improve acceleration, and prevent engine overheating during the high-power demands of this operation phase.

In contrast, the other operation phases have different mixture requirements. For example, during cruising, a leaner mixture is often preferred to maximize fuel efficiency and engine performance. During landing, power needs may be reduced, allowing for a more balanced mixture. Taxiing generally requires minimal power settings, making a lean mixture suitable as well. Therefore, takeoff is the primary phase where a rich mixture is crucial for optimal engine function.