Radar Altimeter Fault Monitoring With Adaptive Terrain Thresholds
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Solution Overview
Problem
Existing radar altitude devices can malfunction, leading to inaccurate altitude data that can cause confusion in synthetic vision systems and Terrain Avoidance and Warning Systems, particularly during critical flight phases, and there is a need for effective fault monitoring that avoids nuisance flagging.
Innovation Solution
An adaptive threshold approach using radar altitude data compared with independent altitude data from GPS or WAAS, adjusted based on terrain fluctuation, to detect and flag faults, ensuring reliable synthetic vision and TAWS operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radar altitude data is used for synthetic vision and TAWS systems, then the systems can provide accurate terrain awareness and visualization, but the systems may experience visual artifacts and confusion when the radar altimeter malfunctions
Solution Approach 1:
The patent introduces an intermediary fault monitoring system that sits between the radar altimeter and the cockpit systems (synthetic vision and TAWS). This monitoring system independently validates radar altitude data by comparing it with terrain database information and other altitude sources, acting as a mediator that filters out faulty data before it reaches the display and warning systems, thereby preventing visual artifacts while maintaining reliable operation
Solution Approach 2:
The patent implements a feedback mechanism where the fault monitoring system continuously checks radar altitude readings against expected terrain profiles and other altitude measurements. When discrepancies are detected, the system generates fault flags that feedback to the cockpit systems, allowing them to adjust their operation or alert the pilots, thus maintaining system reliability while preventing harmful visual artifacts
2Reliability
If fault monitoring is implemented to detect radar altimeter malfunctions, then the reliability of cockpit systems is improved, but the complexity of the system increases
Solution Approach 1:
The patent applies multi-functionality by designing the fault monitoring system to perform multiple functions simultaneously: it validates radar altitude readings, compares them with terrain database information, cross-checks with other altitude sources, generates fault flags, and provides feedback to multiple cockpit systems. This consolidates what could be multiple separate systems into one universal monitoring unit, improving reliability while managing complexity
Solution Approach 2:
The fault monitoring system is designed to be self-sufficient by using internally available data sources (terrain database, other altitude measurements) to validate radar altitude readings without requiring additional external sensors or complex infrastructure. The system automatically detects faults and generates appropriate flags, reducing the need for manual monitoring and simplifying the overall system architecture
3Measurement precision
If fault detection thresholds are set to be sensitive to detect all potential faults, then the detection capability is improved, but the system may experience nuisance flagging of normal variations
Solution Approach 1:
The patent implements dynamic threshold adjustment where the fault detection criteria are not fixed but adapt based on current flight conditions, terrain type, and the specific characteristics of the radar altimeter. The monitoring system learns normal variations for different terrain types and adjusts its sensitivity accordingly, allowing high detection precision for actual faults while dynamically suppressing false alarms during normal operations, thus maintaining reliable fault flagging
Solution Approach 2:
The system changes multiple parameters simultaneously to optimize fault detection: it adjusts detection thresholds based on terrain type, modifies comparison criteria based on flight phase, and varies the weight given to different altitude sources. By dynamically changing these parameters rather than using fixed thresholds, the system achieves high sensitivity to real faults while minimizing nuisance flagging of normal variations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively reduces the likelihood of inaccurate altitude data being used, minimizing visual artifacts and enhancing safety by adaptively adjusting fault detection thresholds based on terrain conditions, thus improving the reliability of cockpit systems.
Implementation Method 1
A radio altimeter (or radar altitude device) uses radar to track the position of an aircraft with respect to the ground. The radio altimeter determines the altitude of the aircraft by reflecting radio waves from the ground.
Data Source
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AI summary
Systems and methods are disclosed that include fault monitoring for a radar altitude device. Fault monitoring is performed by receiving first altitude data from the radar altitude device, receiving second altitude data from a second altitude measuring device, receiving terrain data from a terrain database, determining a fault condition threshold adaptively based on the terrain data, determining whether the radar altitude device is exhibiting a fault condition based on the first and second altitude data and the fault condition threshold, and outputting an indication of the fault condition based on the determination of whether the radar altitude device is exhibiting the fault condition.