Aircraft Guidance Speed Margin for Reliable Waypoint Arrival
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Solution Overview
Problem
Current 4D trajectory-based air traffic management systems face reliability issues due to steady wind errors, which can lead to inadequate spacing between aircraft, inefficient fuel use, increased pilot workload, and structural stress, particularly when attempting to maintain a Required Time of Arrival (RTA) at a waypoint.
Innovation Solution
The system implements a guidance margin strategy that temporarily adjusts aircraft speed to compensate for wind and temperature errors, combining long-term and short-term strategies to maintain trajectory reliability and reduce engine activity, airbrake usage, and vertical path recapture maneuvers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a long-term speed profile is used to reach RTA, then fuel efficiency is improved, but reliability deteriorates due to wind and temperature errors causing time drift
Solution Approach 1:
The system pre-computes a long-term speed profile that is fuel-efficient for reaching the RTA waypoint. This preliminary speed profile is then adjusted in real-time by a guidance margin that compensates for wind and temperature errors, allowing the system to maintain both fuel efficiency and reliability.
Solution Approach 2:
The system continuously monitors actual position and time against the predicted trajectory, and uses this feedback to adjust the guidance margin. This feedback mechanism compensates for wind and temperature errors that cause time drift, maintaining RTA reliability while preserving the fuel efficiency of the long-term speed profile.
2Reliability
If speed adjustments are made to compensate for wind errors, then RTA reliability is improved, but engine activity and fuel consumption increase
Solution Approach 1:
Instead of making continuous full-speed adjustments to compensate for wind errors, the system applies a partial correction through the guidance margin. This margin is calculated based on predicted wind and temperature errors, providing just enough correction to maintain RTA reliability without excessive engine activity or fuel consumption.
3Reliability
If frequent speed corrections are applied to maintain 4D trajectory, then trajectory reliability is improved, but pilot workload and structural stress increase
Solution Approach 1:
The system pre-calculates a long-term speed profile that establishes the fundamental trajectory. This preliminary profile reduces the need for frequent pilot interventions, as the majority of trajectory management is handled by the pre-computed fuel-efficient speed profile rather than continuous corrections.
Data Source
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Figure 5A~5B
AI summary
A method and apparatus includes long term and short term strategies for improving 4D trajectory reliability and required time of arrival reliability. The long term strategy changes speeds along the trajectory to remove the time error in predictions. The short term strategy compensates for wind and position error, for example, by temporarily changing an aircraft guidance speed by applying a guidance margin that would either delay or prevent recomputation of the speed targets along the flight path. The predictions would use the original speed target without the guidance margin application. The guidance speed target will stay applied until the predicted time error crosses a threshold.