L-1011 Autoflight: Altitude Select Mode (22-26)

Altitude select mode provides the capability of selecting a desired altitude to be captured. It can be used for either autopilot control or flight director guidance and is compatible with any roll axis mode.

Engagement of altitude select is accomplished by entering the desired altitude in the altitude select window using the altitude select knob. Below 10,000 feet a twenty-foot change in altitude will automatically arm the altitude select mode. Above 10,000 feet, a 100-foot altitude change is required. Any altitude between 0 and 59,000 feet may be selected.

Verification of mode engagement is accomplished by observing the ALT ARM message on both AFCS MODES annunciators.

The mode may be manually released by disengaging both flight directors and disconnecting the autopilot from the command (CMD) configuration. It will be automatically released if a required interlock function is lost or, if after initiation of the altitude capture maneuver, a superseding pitch axis mode is selected.

If an autopilot is not engaged in CMD, and the ALT Select Flight Director Guidance Commands are followed, the altitude capture maneuver will be asymptotic, with subsequent automatic engagement of the ALT Hold mode for flight director guidance only.