Avionics Anchor Point Calculation for Shifted Runway Thresholds

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Solution Overview

Problem

Current non-precision approach methods for aircraft landing, particularly in FLS type, face challenges in determining the anchor point of a virtual trajectory when the runway threshold is not available or is temporarily shifted, leading to reduced availability and robustness, especially when the virtual trajectory orientation relative to the runway axis is not aligned or is beyond the threshold.

Innovation Solution

A method implemented in an avionics computer using a flight management system that determines the anchor point by comparing the altitude of a missed approach point to a threshold altitude, calculating a terminal point with a slope matching the missed approach to final approach segment, and using this point as the anchor, independent of the runway threshold position, which is regularly updated.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the anchor point is determined using the runway threshold position, then the non-precision approach can be implemented according to standard procedures, but the system becomes unavailable when the runway threshold is temporarily shifted or not updated in the navigation database

Engineering Contradiction:

Improveavailability of non-precision approach modeVSAvoidability to handle runway threshold shifts

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention introduces an intermediary calculation process that determines the anchor point based on the missed approach point and virtual trajectory geometry rather than directly using the runway threshold position. This intermediary method allows the system to maintain functionality even when the runway threshold is temporarily shifted or not updated, as the calculation uses alternative reference points (missed approach point, final approach point) that remain valid.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the parameters used for anchor point determination from runway threshold coordinates to a geometric calculation based on the missed approach point, final approach point, and slope constraints. This parameter transformation allows the system to adapt to situations where the runway threshold position is unavailable or incorrect, maintaining approach availability through alternative parameter sets.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the virtual trajectory is oriented such that it crosses the runway axis downstream of the threshold or has the missed approach point beyond the threshold, then the approach may be geometrically valid, but the anchor point cannot be determined using conventional methods

Engineering Contradiction:

Improvehandling of various trajectory orientationsVSAvoiddeterminability of anchor point

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention inverts the conventional approach by not starting from the runway threshold and working upstream, but rather starting from the missed approach point and working downstream to determine the anchor point. This inversion allows the system to handle cases where the missed approach point is beyond the runway threshold or where the trajectory orientation would make conventional determination impossible, as the calculation flows in the opposite direction from the traditional method.

Inventive Principle:

Principle #13The other way round (Inversion)

3Stability of the object's composition

If the runway threshold position is not updated in the navigation database during temporary works, then the database remains unchanged, but the anchor point determination becomes incorrect

Engineering Contradiction:

Improvestability of navigation databaseVSAvoidaccuracy of anchor point position

Core Design Contradiction:

Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The invention performs preliminary action by calculating the anchor point position dynamically during the approach setup based on current trajectory geometry and missed approach point data, rather than relying on pre-stored runway threshold information in the navigation database. This preliminary calculation ensures that even if the database contains outdated threshold information, the anchor point is determined accurately using current operational parameters.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP4372722A1Method and avionics calculator for determining an anchoring point of a terminal segment from an interrupted approach point, for a non-precision approach

Publication Date: 2024.05.22 AIRBUS OPERATIONS (SAS)

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Figure 3~5

AI summary

- Method and avionics computer for determining an anchor point of a terminal segment from a missed approach point, for a non-precision approach. - The avionics computer, in particular a flight management system, includes a processing unit configured to compare a first altitude (A1) to a so-called threshold altitude (A3), the first altitude corresponding to the altitude (A1) of a missed approach point (MAP) relative to the runway (3), the threshold altitude (A3) being equal to the sum of a second altitude (A2) corresponding to the altitude of the runway (3) and a runway threshold height (TCH), and to determine a terminal point (6) whose altitude is equal to the threshold altitude (A3) and whose straight segment (5B) which it forms with the position (P1) of the missed approach point (MAP) has a slope (β) equal to that of the straight segment (5A) defined by the missed approach point (MAP) and a final approach point (FAF),said terminal point (6) being capable of being used as an anchor point (AP), the avionics computer thus exhibits improved properties, particularly in terms of availability and robustness.