Adjusting Sink Rate Alert Envelopes for Raised Landing Zones
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Solution Overview
Problem
Current ground proximity warning systems for helicopters do not provide timely sink rate alerts when approaching raised landing zones, as they rely solely on radio altitude information, leading to insufficient reaction time for pilots when the sink rate is excessive.
Innovation Solution
A system that adjusts the sink rate alert envelope based on landing zone information, using a combination of radio altimeter, barometric altimeter, and other sensors to generate alerts when the aircraft's sink rate exceeds a threshold adjusted according to the LZ altitude, ensuring timely warnings for pilots approaching raised landing zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the sink rate alert function uses only radio altitude information, then the system complexity is reduced, but the alert timing is delayed and insufficient for raised landing zones
Solution Approach 1:
The alert system is segmented into multiple independent alert modes (Mode 1 for raised LZ, Mode 2 for normal terrain) that can be selectively activated based on the detected landing zone type. This allows the system to use different alerting strategies for different scenarios without increasing overall system complexity.
Solution Approach 2:
The system performs preliminary detection of the landing zone type using GPS coordinates and database lookup before the approach phase. Based on this preliminary identification, the system pre-configures the appropriate alert mode (Mode 1 or Mode 2), ensuring the correct alert timing is active before the pilot needs to react.
2Loss of time
If the sink rate alert envelope is adjusted based on LZ altitude information, then the alert timing is improved, but the device complexity increases
Solution Approach 1:
The sink rate alert envelope is made dynamic by adjusting it based on the detected LZ type. For raised landing zones, the system activates Mode 1 with an extended alert envelope that triggers earlier in the approach. For normal terrain, Mode 2 uses the standard envelope. This dynamic adaptation improves alert timing without requiring a completely new system.
Solution Approach 2:
A database of known raised landing zones with their GPS coordinates serves as an intermediary between the GPS receiver and the alert generator. The system queries this database to determine if the target LZ is raised, and this intermediate information drives the selection of the appropriate alert mode, simplifying the overall control logic.
3Measurement precision
If the system uses GPS and database lookup to identify raised LZ, then the accuracy of alert timing is improved, but the loss of time for data processing increases
Solution Approach 1:
The system performs GPS coordinate comparison with the database of raised LZs during the approach phase, well before the critical decision point. This preliminary identification allows sufficient time for data processing and mode selection without delaying the actual alert to the pilot.
Data Source
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AI summary
Method and corresponding system for improving sink rate alerting for rotary wing aircraft (12). In one example, the system (10) includes a radio altimeter (28) that produces an altitude value, a processor (20) that is in signal communication with the user interface device and the radio altimeter. The processor receives an altitude value, a position value for the aircraft and landing zone information. The processor determines if the aircraft is on an approach to land at a landing zone that is raised above surrounding terrain based on the received position value and landing zone information. The processor receives sink rate information for the aircraft and generates a sink rate alert based on the received sink rate information and the aircraft altitude value if the sink rate information is greater than a sink rate value adjusted according to the landing zone information. An output device (22, 24, 34) outputs the generated sink rate alert. The landing zone information includes an altitude value.