The target speed is provided by the FMS, and the target altitude will be the lower of sim/cockpit2/autopilot/altitude_dial_ft and sim/cockpit2/autopilot/altitude_vnav_ft. Upon selection in the climb phase, the autopilot vertical axis will be speed-by-pitch, and the autothrottle will go to REF mode. VNAV climb and cruiseįor Airliner-VNAV to be selected (dataref sim/cockpit2/autopilot/fms_vnav or command sim/autopilot/FMS) in the climb or cruise phase requires the plane to have auto-throttle. “Airliner” with auto-throttle uses the auto-throttle to set climb power in climb, hold the selected cruise speed in cruise, and comply with speed restrictions (if physically achievable) in descend. “GA” without auto throttle can only do geometric descents – the vertical path is controlled by the autopilot, while the pilot controls the speed by the throttle (or speedbrakes). The main difference is the availability of auto-throttle. X-Plane knows two different types of VNAV, which can be described as “GA” and “Airliner”-type VNAV.
