Flight Management System Ground Track Determination
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Solution Overview
Problem
Current flight management systems face computational complexity and high development costs in accurately calculating and defining aircraft ground tracks on the World Geodetic System 84 (WGS-84) ellipsoidal earth model, which is required for precise 4D trajectory planning, due to the need for complex geodetic algorithms and software development.
Innovation Solution
A method that uses a hybrid great circle approach, combining great circle path calculations with geodetic turn calculations to determine ground tracks, allowing for the insertion of anchor points on a geodesic to adjust the flight path, thereby reducing computational load and development costs while ensuring accuracy and compliance with regulatory thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If geodetic algorithms are used to accurately compute ground tracks on the WGS-84 ellipsoidal earth model, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The flight path is divided into multiple flight legs, each connecting two consecutive waypoints. For each flight leg, the system determines a ground track based on a spherical earth model, then checks if it exceeds regulatory thresholds. This segmentation allows the complex ellipsoidal problem to be broken into manageable spherical segments that can be processed individually with simpler computations.
Solution Approach 2:
The patent introduces an intermediary approach by using spherical earth model calculations as a first approximation, then applying corrective logic when thresholds are exceeded. This intermediary spherical model serves as a computationally efficient proxy for the more accurate but complex ellipsoidal model, resolving the contradiction between precision and complexity.
2Measurement precision
If geodetic algorithms are used to accurately compute ground tracks on the WGS-84 ellipsoidal earth model, then measurement precision is improved, but productivity decreases
Solution Approach 1:
By segmenting the flight path into individual flight legs and processing each leg separately with spherical earth model calculations, the system achieves rapid computation. Only when threshold violations occur does the system engage in more computationally intensive corrective calculations, thereby maintaining high overall productivity while ensuring accuracy where needed.
Solution Approach 2:
The system applies the more accurate ellipsoidal model only partially - specifically when and where threshold violations occur - rather than applying it universally. This partial application of the complex model maintains productivity by avoiding unnecessary computational overhead while still achieving the required precision when needed.
3Measurement precision
If new software is developed to implement geodesic algorithms on the WGS-84 ellipsoidal earth model, then measurement precision is improved, but ease of manufacture worsens
Solution Approach 1:
The patent leverages existing spherical earth model software and algorithms as a base, copying their computational structure and logic. Rather than developing entirely new ellipsoidal software from scratch, the system adapts and modifies existing spherical model code, significantly reducing development and certification costs while improving accuracy through the threshold-based corrective approach.
Solution Approach 2:
The spherical earth model software is made multi-functional by adding threshold checking and corrective logic. This existing software infrastructure serves dual purposes: providing rapid initial calculations and serving as a foundation for the enhanced accuracy system, thereby reducing the need for entirely new software development.
4Measurement precision
If new software is developed to implement geodesic algorithms on the WGS-84 ellipsoidal earth model, then measurement precision is improved, but ease of operation worsens
Solution Approach 1:
By copying and adapting existing spherical earth model software that is already certified and operational, the system avoids the complex and time-consuming process of certifying entirely new software. The threshold-based corrective layer is added to existing proven software, significantly simplifying the certification process while achieving the required WGS-84 compliance.
Data Source
AI summary
A flight management system device and method. The method includes determining a ground track for a flight leg based on a spherical earth model. The flight leg includes two waypoints that are specified with an ellipsoidal earth model. The method includes determining that a parameter associated with the ground track exceeds a threshold. The method includes inserting an anchor point between the two waypoints on a geodesic to effect a course change to the ground track between the two waypoints such that an intended flight path is within specified thresholds. The geodesic is associated with the ellipsoidal earth model. The method includes modifying the ground track to include two spherical earth model path segments spanning from the first waypoint through the anchor point to the second waypoint. The two spherical earth model path segments are computed based on the spherical earth model. The method includes storing modified ground track data.