What must occur for thrust settings to switch to CLB phase during a climb?

For thrust settings to switch to the CLB (Climb) phase during a climb, a vertical mode change must be commanded. This transition is crucial as it signals the aircraft's autopilot to adjust the engine thrust to optimize performance for climbing. In the CLB phase, engines will automatically provide the necessary thrust to achieve an optimal ascent rate while managing fuel efficiency.

The vertical mode command is a key component in the aircraft's automation systems that manages altitude and climb rate. When the aircraft changes its vertical mode to climb, the systems know to adjust the thrust setting accordingly to maintain the desired climb profile. This automation allows for more precise control and efficiency during ascent, reducing pilot workload and enhancing safety.

In contrast, the other options do not contribute directly to the transition of thrust settings. The status of the landing gear, the altitude of the aircraft, or the position of the flaps are not primary factors influencing the switch to CLB thrust settings in the context of the aircraft's flight management system. Each of these components may play a role in other phases of flight, but they do not specifically trigger the transition of thrust settings from the current phase to CLB.