Which is NOT a defined thrust lever position by a stop or detent?

The thrust lever positions that are defined by a stop or detent refer to specific settings that the thrust levers can be placed in during various phases of operation. Each of these defined positions serves a particular operational purpose or performance requirement within the aircraft's operation.

The correct answer highlights that REV IDLE is not a defined thrust lever position by a stop or detent. Unlike the other options, which include thrust settings that the pilots can engage directly via physical stops on the thrust levers (such as CL or the climb thrust position, TO/GA for takeoff/go-around, and FLX/MCT for flexible or maximum continuous thrust), REV IDLE is a position that the thrust levers can reach when moving them back beyond idle for reverse thrust operation. Reverse thrust is automatically managed by the aircraft systems once the thrust levers are pulled back after landing, but it does not involve a physical stop that pilots would engage during normal operations.

Understanding this distinction helps pilots know how to interact with the thrust lever system appropriately during various flight phases.