Which control on the AFCSCP engages the ATS into speed select mode?

The Speed SEL knob on the Automatic Flight Control System Control Panel (AFCSCP) is designed specifically to engage the Auto Throttle System (ATS) into speed select mode. When this control is activated, it allows the aircraft to maintain a specific airspeed by automatically adjusting the throttle position as necessary.

Using the Speed SEL knob, pilots can set a target airspeed, enabling the aircraft to respond dynamically to changing conditions such as altitude and configuration. This capability is particularly useful during phases of flight where maintaining a precise speed is critical for performance and safety, such as during approach and landing.

Other controls on the panel serve different functions and do not engage the ATS in speed select mode. For example, the THR/PITCH pushbutton primarily engages modes related to thrust and pitch management, while the MACH/IAS pushbutton allows switching between Mach and indicated airspeed modes. The bank angle selector knob is used to set specific bank angles for turns and does not interact with the auto throttle system in the context of speed selection.