TAWS Altitude Correction Using Temperature Compensation and GPS
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Solution Overview
Problem
Current aircraft avionics systems, such as Terrain Alert and Warning Systems (TAWS), face inaccuracies in terrain altitude warnings due to altimeter errors and non-standard atmospheric conditions, leading to potential false alarms or missed warnings, especially in mountainous areas and during temperature deviations from International Standard Atmosphere (ISA) conditions.
Innovation Solution
The system determines the aircraft's corrected altitude and applies a coordinate system transformation between corrected and uncorrected altitude scales to provide accurate terrain alerts, accounting for altimeter errors and non-standard atmospheric conditions, ensuring real-time depiction of the aircraft's separation from terrain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barometric altimeter is used for terrain alerting, then the system can provide altitude information, but altitude accuracy deteriorates under non-standard atmospheric conditions
Solution Approach 1:
The system changes the reference parameter from standard atmospheric conditions to actual measured temperature conditions. By using measured temperature to dynamically adjust the altitude calculation, the system adapts to non-standard atmospheric conditions and maintains accurate terrain separation assessment
Solution Approach 2:
The patent introduces temperature measurement as an intermediary parameter that mediates between barometric pressure and true altitude. The temperature data serves as a correction factor that reconciles the discrepancy between indicated altitude and true altitude under non-standard conditions
2Measurement precision
If temperature compensation is applied to correct altitude errors, then terrain alert accuracy improves, but system complexity increases
Solution Approach 1:
The system makes the temperature sensor serve multiple functions: it compensates for altitude indication errors in TAWS, provides performance data for aircraft systems, and enables prediction of icing conditions. This multi-functionality justifies the added complexity by providing value across multiple aviation safety and performance domains
3Measurement precision
If GPS altitude data is used instead of barometric altimeter, then altitude accuracy under non-standard conditions improves, but compatibility with existing flight plan systems deteriorates
Solution Approach 1:
The system introduces a coordinate transformation as an intermediary process that bridges GPS geometric altitude and barometric altitude reference frames. This transformation layer allows GPS data to be used for accurate terrain separation assessment while maintaining compatibility with existing flight plan systems that operate in the barometric reference frame
Data Source
AI summary
A method of accounting for errors in the altitude reporting of a terrain alert and warning system (TAWS) is disclosed wherein errors due to non-standard atmospheric conditions, incorrect altimeter setting and air data computer (ADC) sensor error are detected and corrected for by compensating ADC altitudes for cold temperatures as well as using global positioning system (GPS) altitude data to confirm the accuracy of the ADC altitude information at all times.