When initiating a climb or descent, what is a key transitional action required?

When initiating a climb or descent in aviation, it's essential to consider multiple aspects of aircraft performance and control. Monitoring engine performance closely is crucial because it provides the pilot with real-time data on efficiency, power output, and potential issues as the aircraft changes altitude. A well-functioning engine is vital for ensuring that the aircraft responds appropriately during these transitions.

Additionally, reducing altitude immediately may seem counterintuitive; however, initiating a descent involves managing airspeed and thrust before changing altitude significantly. This careful adjustment helps ensure a smooth transition. Therefore, both monitoring engine performance and managing altitude changes (implying careful control rather than immediate altitude reduction) are key transitional actions when climbing or descending. Hence, when considering the need for both engine performance oversight and managing altitude changes reasonably, the combination of these actions becomes crucial in executing a proper climb or descent.