Automatic Air Data Source Selection for RVSM Altitude Accuracy
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Solution Overview
Problem
Aircraft operating in Reduced Vertical Separation Minima (RVSM) airspace face challenges in maintaining altitude accuracy within 200 ft tolerance, especially at higher Mach numbers, as existing air data systems experience larger errors, and there is no way to predict which air data probe the pilot will use, necessitating improved accuracy and faster cruise speeds while remaining compliant with RVSM requirements.
Innovation Solution
A method and system for selecting and ranking the accuracies of pressure altitude sensing devices by receiving pressure altitudes, calculating a reference altitude using signals from aircraft sensors, comparing and ranking each device based on differences, prioritizing displays, and displaying readings on cockpit displays, allowing for automatic selection of the best air data source and reducing overall altimetry system error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional air data probes are used for altitude sensing in RVSM airspace, then the system can provide altitude data, but the measurement precision deteriorates at higher Mach numbers with errors exceeding 200 ft tolerance
Solution Approach 1:
The patent introduces an intermediary system (altimetry system with multiple sensors including barometric pressure sensors, GPS, and inertial reference systems) that mediates between the unreliable single air data probe and the RVSM requirement. This intermediary system cross-validates data from multiple sources to determine accurate altitude, thereby resolving the contradiction between probe error and RVSM compliance.
Solution Approach 2:
The system changes the parameter of altitude determination from relying on a single air data probe to using multiple independent sensing methods (barometric pressure, GPS position, inertial data). By changing how altitude is measured rather than improving a single probe, the system achieves the required 200 ft accuracy even at high Mach numbers.
2Productivity
If pilots manually select air data probes, then the system can operate with simple architecture, but the productivity decreases due to inability to automatically optimize for accuracy at varying flight conditions
Solution Approach 1:
The system performs preliminary actions by continuously monitoring and evaluating the accuracy of multiple air data probes before pilot selection is needed. The automatic selection system pre-determines which probe provides the most accurate data based on current flight conditions (Mach number, altitude), so when the pilot needs altitude information, the system has already optimized the selection, enabling faster cruise speeds without manual intervention delays.
Solution Approach 2:
The system implements feedback by continuously comparing data from multiple air data probes against expected performance characteristics and flight conditions. This feedback loop automatically identifies which probe is providing the most accurate data and adjusts selections accordingly, enabling the system to maintain optimal accuracy across varying flight conditions without increasing apparent complexity to the pilot.
3Reliability
If multiple air data probes are installed, then the system has redundant sources for RVSM requirements, but the difficulty of detecting and measuring accuracy increases as there is no way to know which source is most accurate
Solution Approach 1:
The system applies self-service by having the air data system automatically evaluate and rank the accuracy of its own multiple probes without external intervention. The system uses its available sensors (barometric, GPS, inertial) to self-assess which probe is providing the most accurate altitude data, eliminating the need for external measurement equipment or complex pilot assessment procedures.
Solution Approach 2:
The patent replaces the mechanical approach of manually selecting probes with an electronic/computational system that automatically evaluates and selects the most accurate probe. This substitution uses computer processing to compare sensor data and determine accuracy, replacing what would otherwise require complex manual assessment mechanisms.
Data Source
AI summary
A system and method for carrying out an automatic selection of the best air data source on an aircraft, through a voting scheme, for determining aircraft altitude and present that information to the pilot. Once this is done, statistical analysis can be done to look at the ‘root mean square’ (RMS) of the possible errors to ensure the airplane remains within a maximum tolerance respecting Reduced Vertical Separation Minima (RVSM) requirements. The aircraft can therefore travel faster cruise speed at higher altitude, thus reducing travel time, while still respecting RVSM requirements