Systems and methods for providing predicted mode change data for decoupled vertical navigation (VNAV) and lateral navigation (LNAV) autopilot operations

A system for providing mode data, onboard an aircraft, during operation of a Flight Management System (FMS) using a Vertical Navigation (VNAV) Autopilot Mode, the system comprising:

• a system memory element;
• the Flight Management System (FMS), configured to:
• engage and disengage a Lateral Navigation (LNAV) Autopilot Mode during flight;
• and
• engage and disengage the VNAV Autopilot Mode during the flight, wherein the LNAV Autopilot Mode and the VNAV Autopilot Mode comprise decoupled modes configured to operate independently;
• a display device, configured to present an aircraft position during the flight;
• and
• at least one processor, communicatively coupled to the system memory element, the FMS, and the display device, the at least one processor configured to:
• when the FMS has disengaged the Lateral Navigation (LNAV) Autopilot Mode,
• detect a changed aircraft position indicating divergence from a flight path, wherein the changed aircraft position comprises a current aircraft position;
• calculate a future aircraft position for VNAV Autopilot Mode disengagement, based on the changed aircraft position, a predicted cross-track error, and the divergence from the flight path;
• present the changed aircraft position and the future aircraft position when operating in the VNAV Autopilot Mode, via the display device communicatively coupled to the FMS;
• when the future aircraft position is not on the flight path, disengage the VNAV Autopilot Mode of the FMS, based on the changed aircraft position and the future aircraft position for VNAV Autopilot Mode disengagement;
• calculate a descent path for the aircraft, after disengagement of the VNAV Autopilot Mode;
• and
• present the descent path, via the display device.