What does the term "intervention" refer to in the context of VNAV operations?

In the context of VNAV operations, the term "intervention" refers specifically to manual adjustments made by pilots when the vertical navigation system is not functioning as expected or is computing incorrectly. This scenario often arises when the automated VNAV system encounters limitations or fails to adhere to programmed altitude profiles due to changes in flight conditions, air traffic, or other operational factors.

Pilots are trained to monitor VNAV performance closely and are prepared to step in and make necessary manual adjustments to maintain safe and effective altitude control. Such interventions can include altering altitude settings, changing the vertical speed, or reconfiguring flight paths to ensure the aircraft adheres to the desired vertical profile safely. This ability to intervene ensures that flight crews maintain control and uphold safety standards, especially in dynamic and changing flight environments.

Other options, while related to flight operations, do not accurately encapsulate the definition of "intervention" in the VNAV context. Automated changes refer to adjustments made independently by the flight management system without pilot input. Communicating with ATC, though essential for safe flight operations, concerns coordination rather than direct intervention in VNAV. Adjustments to engine power are critical for overall aircraft performance but are not specifically tied to the vertical navigation system’s functioning.