Airplane position assurance monitor
First Claim
1. A method for monitoring positional accuracy of an airplane approaching a runway, comprising the following steps performed by a computer system during the approach:
- (a) determining a ground distance between a location of the airplane and a touchdown aim point on the runway based on respective coordinates thereof;
(b) determining a height of the airplane above a threshold of the runway based on an altitude of the airplane and an elevation of a threshold of the runway;
(c) determining an angle between a hypothetical line extending from the airplane to the touchdown aim point and a perpendicular projection of that line onto a locally level plane that passes through a runway threshold reference point based on the ground distance and the height;
(d) determining a first vertical angular deviation of the airplane from a glideslope based on a difference of the determined angle and a glide path angle;
(e) receiving a second vertical angular deviation of the airplane from the glideslope based on measurements of a difference in a depth of modulation of first and second modulated signals transmitted from a ground-based antenna and received by an antenna onboard the airplane;
(f) comparing the first and second vertical angular deviations; and
(g) generating an alert signal when the first and second vertical angular deviations differ by an amount greater than a threshold value.
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Accused Products
Abstract
An onboard monitor that ensures the accuracy of data representing the calculated position of an airplane during final approach to a runway. This airplane position assurance monitor is a software function that uses dissimilar sources of airplane position and runway data to ensure the accuracy of the respective data from those dissimilar sources. ILS data and GPS or GPS/Baro data are the dissimilar sources of airplane position data used by this function. This function will calculate the airplane'"'"'s angular deviations from the runway centerline and from the glide slope with onboard equipment and then compare those angular deviations to the ILS angular deviation information.
30 Citations
16 Claims
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1. A method for monitoring positional accuracy of an airplane approaching a runway, comprising the following steps performed by a computer system during the approach:
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(a) determining a ground distance between a location of the airplane and a touchdown aim point on the runway based on respective coordinates thereof; (b) determining a height of the airplane above a threshold of the runway based on an altitude of the airplane and an elevation of a threshold of the runway; (c) determining an angle between a hypothetical line extending from the airplane to the touchdown aim point and a perpendicular projection of that line onto a locally level plane that passes through a runway threshold reference point based on the ground distance and the height; (d) determining a first vertical angular deviation of the airplane from a glideslope based on a difference of the determined angle and a glide path angle; (e) receiving a second vertical angular deviation of the airplane from the glideslope based on measurements of a difference in a depth of modulation of first and second modulated signals transmitted from a ground-based antenna and received by an antenna onboard the airplane; (f) comparing the first and second vertical angular deviations; and (g) generating an alert signal when the first and second vertical angular deviations differ by an amount greater than a threshold value. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system for monitoring positional accuracy of an airplane approaching a runway, comprising:
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a glideslope receiver for determining a first vertical angular deviation of the airplane from the glide slope based on measurements of a difference in a depth of modulation of first and second modulated signals transmitted by a ground-based glide slope transmitter; and a computer system that is programmed to perform the following operations during the approach; (a) determining a ground distance between a location of the airplane and a touchdown aim point on the runway based on respective coordinates thereof; (b) determining a height of the airplane above a threshold of the runway based on an altitude of the airplane and an elevation of a threshold of the runway; (c) determining an angle between a hypothetical line extending from the airplane to the touchdown aim point and a perpendicular projection of that line onto a locally level plane that passes through a runway threshold reference point based on the ground distance and the height; (d) determining a second vertical angular deviation of the airplane from a glideslope based on the computed angle and a glide path angle; (e) comparing the first and second vertical angular deviations; and (f) generating an alert signal when the first and second vertical angular deviations differ by an amount greater than a threshold value. - View Dependent Claims (8, 9, 10, 11)
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12. A method for monitoring positional accuracy of an airplane approaching a runway, comprising the following steps performed by a computer system during the approach:
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(a) calculating a ground distance between a location of the airplane and a touchdown aim point on the runway based on respective coordinates thereof and not using vertical angular deviation; (b) calculating a height of the airplane above a threshold of the runway based on an altitude of the airplane and an elevation of a threshold of the runway and not using vertical angular deviation; (c) calculating an angle between a hypothetical line extending from the airplane to the touchdown aim point and a perpendicular projection of that line onto a locally level plane that passes through a runway threshold reference point based on the ground distance and the height and not using vertical angular deviation; (d) calculating a first vertical angular deviation of the airplane from a glideslope based on a difference of the calculated angle and a glide path angle; (e) calculating a second vertical angular deviation of the airplane from the glideslope based on measurements of a difference in a depth of modulation of first and second modulated signals transmitted from a ground-based antenna and received by an antenna onboard the airplane; (f) comparing the first and second vertical angular deviations; and (g) generating an alert signal when the first and second vertical angular deviations differ by an amount greater than a threshold value. - View Dependent Claims (13, 14, 15, 16)
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Specification