VNAV Mode Change Prediction During Decoupled LNAV Operations
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Solution Overview
Problem
During high workload phases of flight, such as descent or approach, flight crew members may not immediately recognize the need for a VNAV mode transition due to complex display configurations presenting multiple VNAV commands and graphical/text elements, increasing pilot workload and reducing situational awareness.
Innovation Solution
A method and system that detect a changed aircraft position indicating divergence from the flight path, calculate a future aircraft position for VNAV Autopilot Mode disengagement based on cross-track error and divergence, and present this information via a display device, disengaging the VNAV Autopilot Mode when the future position is off the flight path, and calculating a descent path for post-disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If multiple VNAV commands and graphical elements are presented on the display, then the system provides comprehensive navigation information, but the pilot workload increases and situational awareness decreases
Solution Approach 1:
The patent extracts and isolates the VNAV mode change information from the complex display configuration. It specifically extracts the future VNAV mode change data and presents it in a dedicated, simplified format that separates this critical information from other navigation displays, reducing the cognitive load on pilots while maintaining comprehensive information availability.
Solution Approach 2:
The system performs preliminary calculation and presentation of future VNAV mode change data before the actual mode change occurs. By calculating and displaying the future mode change information in advance, the system allows pilots to prepare for upcoming changes during high workload phases, improving situational awareness without requiring complex real-time display configurations.
2Reliability
If the VNAV Autopilot Mode remains engaged after LNAV disengagement, then the system maintains automated vertical navigation, but the aircraft may accumulate lateral position errors
Solution Approach 1:
The system calculates the future aircraft position and determines the optimal disengagement point for VNAV mode in advance, before lateral position errors become significant. This preliminary calculation allows the system to maintain automated vertical navigation during decoupled operation while proactively identifying when disengagement is necessary to prevent error accumulation.
Solution Approach 2:
The system continuously monitors the aircraft position and calculates future positions to provide feedback on lateral deviation. This feedback mechanism enables the system to determine when the aircraft has diverged sufficiently from the flight path, triggering VNAV mode disengagement to maintain both vertical navigation reliability and lateral position accuracy.
3Reliability
If the system calculates future aircraft position for VNAV disengagement, then the system prevents error accumulation, but the computational complexity and processing time increase
Solution Approach 1:
The patent extracts only the essential parameters needed for future position calculation (current position, velocity, and flight path information) rather than processing all available navigation data. This selective extraction reduces computational complexity while maintaining the reliability needed to prevent error accumulation during decoupled VNAV operation.
Data Source
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AI summary
A method for providing mode data during operation of a Flight Management System (FMS) using a Vertical Navigation (VNAV) Autopilot Mode, is provided. When the FMS has disengaged a Lateral Navigation (LNAV) Autopilot Mode, the method detects a changed aircraft position indicating divergence from a flight path, wherein the changed aircraft position comprises a current aircraft position; calculates 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; and presents the changed aircraft position and the future aircraft position when operating in the VNAV Autopilot Mode, via a display device. When the future aircraft position is not on the flight path, the method disengages the VNAV Autopilot Mode, based on the changed aircraft position and the future aircraft position; calculates a descent path for the aircraft, after disengagement; and presents the descent path.