Precision Landing Navigation Using Forward-Looking Radar Terrain Modeling
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Solution Overview
Problem
Current aircraft navigation systems, particularly in adverse weather conditions and rough terrain, face challenges in accurately determining vertical height above the runway threshold, limiting precision landings to Cat I or Cat II minimums, as GPS-based solutions lack the accuracy of Cat III ILS installations.
Innovation Solution
A combination of GPS-WAAS data, X-Band forward-looking radar, and radio altimeter is used to generate a real-time terrain model, allowing for precise computation of aircraft vertical position relative to the runway threshold, enhancing accuracy and enabling precision landings below Cat II minima without ground installations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If GPS-based solutions are used for precision approach, then the system can operate autonomously without ground installations, but the vertical height determination accuracy is insufficient especially in adverse weather conditions and rough terrain
Solution Approach 1:
The patent combines multiple sensing systems (GPS receiver, forward-looking radar, radio altimeter, inertial reference system) into an integrated navigation system. The processor fuses data from all these sources to compute accurate vertical height above the runway threshold, achieving both autonomous operation and high precision by merging complementary measurement capabilities.
Solution Approach 2:
The forward-looking radar acts as an intermediary to generate real-time terrain models that bridge the gap between GPS position data and actual runway threshold location. This terrain model serves as a mediator to correct and refine the vertical height calculations, enabling accurate HATDZ determination without ground-based installations.
2Device complexity
If conventional navigation sensors are used during turns, then the system structure is simple, but accurate altitude readings cannot be maintained during turning flight
Solution Approach 1:
The forward-looking radar serves as an intermediary measurement tool that can accurately determine vertical height during turns when conventional sensors fail. The radar's line-of-sight measurement capability provides reliable altitude data independent of aircraft orientation, acting as a mediator to maintain precision during maneuvering flight.
Solution Approach 2:
The patent replaces reliance on mechanical/conventional sensors (radio altimeter, inertial reference) with an optical/electromagnetic-based forward-looking radar system for height determination during turns. This substitution enables accurate altitude measurement during dynamic maneuvers where traditional mechanical systems become unreliable.
3Measurement precision
If GPS with SBAS is used for precision approach, then descent to 200 feet HATDZ is achievable, but descent below this level to Cat II or Cat III minima cannot be provided
Solution Approach 1:
The system carries its own forward-looking radar and terrain modeling capabilities onboard, making it self-sufficient for generating real-time terrain models and determining vertical height. This autonomous self-service capability eliminates dependence on ground-based augmentation infrastructure, enabling descent to Cat II and Cat III minima without external support.
Solution Approach 2:
The patent adds a new dimension of real-time terrain modeling capability to the traditional GPS/SBAS vertical measurement system. By incorporating forward-looking radar data to create detailed terrain models, the system extends its operational capability from 200 feet HATDZ to below 100 feet HATDZ, accessing new operational dimensions previously unavailable with GPS alone.
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 system provides improved accuracy for precision landings by generating a real-time terrain model using X-Band radar, supplementing conventional navigation sensors, and maintaining accurate altitude readings during turns, thus overcoming the limitations of GPS-based solutions in adverse conditions.
Implementation Method 1
utilization of an X-Band forward-looking radar to produce a real time terrain model
Implementation Method 2
allow the use of a radio altimeter to compute aircraft vertical position relative to the runway threshold
Data Source
AI summary
In the examples described the forward-looking radar generated real-time terrain model (or in an alternative example in combination with a terrain database), can allow the use of a radio altimeter to compute aircraft vertical position relative to the runway threshold. Such a system typically provides improved accuracy for precision landings.