Fault-Tolerant Lateral Waypoint Sequencing in Flight Management Computers
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Solution Overview
Problem
Current flight management systems lack fault tolerance in lateral waypoint sequencing, particularly for Required Navigation Performance (RNP) operations with restrictions ≤ 0.3 NM, which requires significant training for flight crews and is incompatible with independent detection and control of leg sequencing operations.
Innovation Solution
A fault-tolerant lateral waypoint sequencing system that includes at least two flight management computers, where each computer implements processing operations associated with lateral leg sequencing and initiates actions if the other computer fails to acknowledge sequencing conditions within a predetermined time, ensuring independent operation and synchronization for precise aircraft path control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional redundant FMS with a single queue of events managed by one master FMC is used, then device complexity is reduced, but reliability deteriorates because errors in the master FMC can be propagated to other FMCs without independent detection
Solution Approach 1:
The patent divides the centralized event queue management into separate, independent event queues in each FMC. Each FMC independently manages its own queue of sequencing events rather than relying on a single master FMC, thereby segmenting the control function to prevent error propagation and improve fault tolerance while maintaining system reliability.
2Reliability
If independent detection and control of leg sequencing operations is implemented, then reliability improves through fault tolerance, but device complexity increases due to multiple FMCs requiring synchronization
Solution Approach 1:
The patent implements a feedback mechanism where each FMC monitors whether the other FMC has processed the same sequencing event by checking for corresponding events in their respective queues. This feedback loop enables independent detection of processing status and automatic synchronization without complex external control, resolving the contradiction between reliability and complexity.
3Manufacturing precision
If RNP restrictions of ≤ 0.3 NM are enforced without independent FMC detection, then manufacturing precision requirements are reduced, but reliability deteriorates due to inability to provide adequate guidance
Solution Approach 1:
The patent performs preliminary independent detection and verification of sequencing conditions in each FMC before executing leg sequencing. By pre-checking whether sequencing conditions are met independently in both FMCs and synchronizing their event queues, the system ensures reliable guidance for high-precision RNP operations without requiring excessive manufacturing precision tolerances.
Data Source
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AI summary
Fault-tolerant lateral waypoint sequencing is provided for a system that includes at least a first flight management computer and a second flight management computer. A processing operation associated with lateral leg sequencing of an aircraft flight plan is implemented in the flight management computers. A determination is made in the first flight management computer as to whether the first flight management computer has received, within a predetermined period of time from when the first flight management computer implemented the processing operation, a notification from the second flight management computer that the second flight has also implemented the processing operation. An action is initiated in the first flight management computer when the first flight management computer has not received the notification from the second flight management computer within the predetermined period of time.