A variation from the optimum flight path during cruise results in what?

A variation from the optimum flight path during cruise generally results in a loss of range capability. This is because cruising at non-optimal altitudes or airspeeds can lead to increased drag and require adjustments in thrust settings to maintain flight. When an aircraft is not operating along its designed optimal flight profile, it often must utilize more fuel than necessary for the given distance. The inefficiency associated with this extra fuel consumption affects range because it shortens the distance the aircraft can cover with a given amount of fuel.

In contrast, improved speed capability, higher fuel efficiency, and increased thrust output are typically associated with maintaining or following the optimal flight path. Deviating from this path generally does not enhance performance metrics and tends to have a negative impact on overall flight efficiency. By adhering to optimal flight parameters, pilots and flight engineers can maximize the aircraft's range and performance.