Aircraft Braking Computer Minimum Deceleration Validation
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Solution Overview
Problem
Existing aircraft automatic braking systems during landing may fail to ensure the aircraft stops before the end of the runway due to errors in deceleration calculations, particularly when relying on data with low integrity.
Innovation Solution
A device with a flight control computer and braking computer, both certified at high integrity levels (DAL A), calculates a minimum deceleration to guarantee the aircraft stops before the runway end by comparing nominal and minimum decelerations, using high-integrity data from inertial reference systems and runway length validation, ensuring accurate ground speed and distance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nominal deceleration is calculated using standard automatic braking systems, then the aircraft can stop at a selected exit on the landing strip, but the calculation may be erroneous and fail to ensure the aircraft stops before the end of the runway
Solution Approach 1:
The system performs preliminary calculations of minimum deceleration using high-integrity data before executing the actual braking maneuver. The flight control computer calculates both nominal deceleration (for optimal exit) and minimum deceleration (for safety margin) in advance, comparing them to ensure the selected deceleration will guarantee stopping before runway end even if nominal calculation is erroneous.
Solution Approach 2:
The invention introduces an intermediary verification mechanism where the flight control computer acts as a mediator between the automatic braking system and the braking actuators. It receives nominal deceleration from the braking system, independently calculates minimum deceleration using high-integrity data, compares both values, and only transmits the validated deceleration command to the braking system, thus ensuring reliability without directly modifying the braking hardware.
2Reliability
If high-integrity data from multiple inertial reference systems is used, then data reliability improves, but system complexity and data processing requirements increase
Solution Approach 1:
The system segments the data integrity verification process into distinct functional modules within the flight control computer: data reception from multiple inertial reference systems, consistency checking between systems, selective data acceptance based on consistency criteria, and calculation of minimum deceleration using accepted high-integrity data. This modular segmentation manages complexity while maintaining high reliability.
Solution Approach 2:
The invention changes the parameter of data selection criteria from simple acceptance to consistency-based selective acceptance. The flight control computer monitors parameters such as ground speed consistency across multiple inertial reference systems and only accepts data when consistency thresholds are met, thereby ensuring high-integrity data input without requiring complex hardware modifications.
Data Source
AI summary
The device (1) includes means (4, 7) which ensure, during taxiing on a runway, that in the nominal case the aircraft will stop at a selected exit, while guaranteeing that in the event of a failure the aircraft will stop before the end of the runway.