Horizontal miss distance filter system for suppressing false resolution alerts
First Claim
1. A system for suppressing a false resolution alert message from an air traffic alert and collision avoidance system, comprising:
- means for input of a surveillance range measurement of an intruder aircraft from the air traffic alert and collision avoidance system;
range tracking means coupled to said surveillance range measurement input means for determining horizontal miss distances greater than a predetermined value using at least a second derivative of a predicted range of the intruder aircraft, said second derivative of said predicted range of the intruder aircraft being greater than a predetermined first threshold value; and
,inhibit means coupled to said range tracking means and the air traffic alert and collision avoidance system for inhibiting transmission of a resolution alert message responsive to said determined horizontal miss distance being greater than said predetermined value.
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Accused Products
Abstract
A horizontal miss distance filter system (220) is provided for inhibiting resolution alert messages from an air traffic alert and collision avoidance system (210) to a pilot'"'"'s display (230). The horizontal miss distance filter employs a parabolic range tracker (10) to derive a range acceleration estimate (11) utilized to discriminate intruder aircraft (110) having non-zero horizontal miss distances. The horizontal miss distance calculated from the range data provided by the parabolic range tracker is compared with a bearing based horizontal miss distance provided by a bearing based tracker (22). The smaller of the two calculated horizontal miss distances defines a projected horizontal miss distance which is compared with a threshold value. Any resolution alert for intruder aircraft whose projected horizontal miss distance is greater than the threshold will be inhibited unless it is determined that the encounter involves a maneuver of one of the aircraft. As many as five maneuver detectors (50, 52, 56, 58 and 64) may be employed to assess whether the encounter involves a maneuver. If any of the maneuver detectors establish the occurrence of a maneuver, then a resolution alert provided from the TCAS system (210) will not be inhibited.
88 Citations
39 Claims
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1. A system for suppressing a false resolution alert message from an air traffic alert and collision avoidance system, comprising:
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means for input of a surveillance range measurement of an intruder aircraft from the air traffic alert and collision avoidance system; range tracking means coupled to said surveillance range measurement input means for determining horizontal miss distances greater than a predetermined value using at least a second derivative of a predicted range of the intruder aircraft, said second derivative of said predicted range of the intruder aircraft being greater than a predetermined first threshold value; and
,inhibit means coupled to said range tracking means and the air traffic alert and collision avoidance system for inhibiting transmission of a resolution alert message responsive to said determined horizontal miss distance being greater than said predetermined value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A system for suppressing a false resolution alert message from an air traffic alert and collision avoidance system, comprising:
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means for input of a surveillance range measurement of an intruder aircraft from the air traffic alert and collision avoidance system; range tracking means coupled to said surveillance range measurement input means for determining horizontal miss distances greater than a predetermined value using at least a second derivative of a predicted range of the intruder aircraft, said second derivative of said predicted range of the intruder aircraft being greater than a predetermined first threshold value, said range tracking means including maneuver detecting means for determining that the intruder aircraft is changing in either direction or relative speed and providing a maneuver indication output; and
,inhibit means coupled to said range tracking means and the air traffic alert and collision avoidance system for inhibiting transmission of a resolution alert message responsive to said determined horizontal miss distance being greater than said predetermined value and an absence of said maneuver indication output. - View Dependent Claims (29, 30)
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31. A method of detecting that an intruder aircraft is maneuvering in an air traffic alert and collision avoidance system, comprising the steps:
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providing measured range values of the intruder aircraft at predetermined time intervals; calculating a predicted range value based on measured range values; calculating a third derivative of said predicted range value; determining an occurrence of a maneuver of the intruder aircraft responsive to said third derivative of said predicted range value being less than zero; and
,inputting an indication of said determined occurrence of a maneuver of the intruder aircraft to an alert filter system for inhibiting said filter system from suppressing an alert message output relative to the intruder aircraft. - View Dependent Claims (32, 33, 34, 35)
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36. A method of suppressing a false resolution alert message from an air traffic alert and collision avoidance system, comprising the steps of:
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a) providing a measured range value to an intruder aircraft; b) calculating a predicted range value, a predicted range velocity value and a predicted range acceleration value based on said measured range value for a predetermined future time interval; c) comparing said predicted range acceleration value with an acceleration threshold value; d) if said predicted range acceleration value is less than said acceleration threshold value, proceeding to step (a), otherwise continuing; e) calculating a projected horizontal miss distance for the intruder aircraft; f) comparing said projected horizontal miss distance with a distance threshold value; g) if said projected horizontal miss distance is less than said distance threshold value, proceeding to step (a), otherwise continuing; h) determining whether there is a change in either of a relative direction or a relative speed of the intruder aircraft to identify a maneuvering condition; i) if said maneuvering condition is identified, proceeding to step (a), otherwise continuing; and
,j) inhibiting a resolution alert message from the air traffic alert and collision avoidance system. - View Dependent Claims (37, 38, 39)
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Specification