A pilot control interface and method are described for selective control of an autopilot system by a pilot of an aircraft in which the autopilot system is installed. The pilot control interface includes a passive network that is selectively switchable between a plurality of states across an output interface that is made up of no more than two conductors that are in electrical communication with the autopilot system. Modification of a current autopilot flight mode can be performed incrementally or continuously based on respective momentary and continuous pilot input actuations.