Definition
The throttle setting used to maintain a desired airspeed and altitude in straight-and-level flight once the aircraft is trimmed and stabilized. It is the cruise power required to hold steady performance, as distinct from the larger power changes used to climb, descend, or accelerate.
Plain English
It is the throttle setting that keeps the aircraft flying level at the speed you want, without climbing, descending, or losing speed.
Context Anchor
Seen in instrument flying discussions of straight-and-level flight and the primary/supporting method of checking instruments.
Derivation
Support comes from the idea of holding something up or assisting it. In this term, the power indication assists the pilot’s main power reference rather than taking its place.
Why Pilots Care
Knowing the supporting power setting for a given airspeed and configuration lets a pilot return to stable level flight quickly after a maneuver, rather than chasing the throttle. It reduces workload and helps maintain precise altitude on instruments.
Intuition Check
Supporting power does not mean extra engine power. It means a power-related indication is being used as a secondary check to support the main power reference.
Example Sentence 1
Once established at cruise altitude, she set the supporting power for 110 knots and trimmed off the control pressures.
Example Sentence 2
The pilot added supporting power to maintain altitude after extending the flaps.