Apparatus, methods, and computer program products for determining a look ahead distance value for high speed flight

• US 6,380,870 B1
• Filed: 02/01/2000
• Issued: 04/30/2002
• Est. Priority Date: 02/01/1999
• Status: Expired due to Term

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Johnson, Steven C., Conner, Kevin J
• Primary Examiner(s): SWARTHOUT, BRENT
• Application Number:
  US09/495,979
• Time in Patent Office: 819 Days
• Field of Search: 340/970, 340/963, 340/961, 701/9, 701/14, 701/4, 701/301, 731/78.T, 244/180, 244/181, 342/65
• US Class Current: 340/970
• CPC Class Codes: G01C 5/005 altimeters for aircraft G01C5/02, G01C5/06 take precedence

Abstract

The present invention provides several apparatus, methods, and computer program products for determining a look ahead distance value for use in a ground proximity warning system. Specifically, the present invention provides apparatus, methods, and computer program products that generate a candidate look ahead distance value that provides a constant reaction time for varying aircraft speeds. The apparatus of the present invention includes a processor that generates the constant reaction time look ahead distance by multiplying a desired reaction time by the speed of the aircraft. This constant reaction time look ahead distance value is compared by the processor to other candidate look ahead distance values that have variable reaction times for varying aircraft speeds. If the aircraft is traveling at a relatively high speed, the processor of the present invention selects the constant reaction time look ahead distance value for use in the ground proximity warning system. Importantly, because the present invention switches from a variable reaction time look ahead distance value to a constant reaction time look ahead distance value when the aircraft is travelling at higher speeds, the present invention can provide a look ahead distance value that reduces nuisance alarms for lower speeds, while also providing at least a minimum reaction time for higher speeds.

Claims

1. An apparatus for determining a look ahead distance value for use in a ground proximity warning system, wherein said apparatus comprises a processor that selects, from a plurality of candidate look ahead distance values, a look ahead distance values representing a distance extending about an aircraft within which the ground proximity warning system provides ground proximity alerts, such that for aircraft speeds below a predetermined threshold speed, the reaction time varies with the speed of the aircraft and for aircraft speeds at least as great as The predetermined threshold speed, the reaction time is constant and a constant reaction time look ahead distance value varies as the speed of the aircraft varies.

2. An apparatus according to claim 1, wherein said speed of the aircraft is the ground speed of the aircraft.

3. An apparatus according to claim 1, wherein said look ahead distance value for aircraft speeds at least as great as die predetermined threshold speed is the speed of the aircraft multiplied by a selected constant reaction time.

4. An apparatus according to claim 3, wherein the selected constant reaction time is sixty seconds.

5. An apparatus according to claim 1, wherein said processor compares the selected look ahead distance value to a predetermined maximum look ahead distance value, and wherein if The selected look ahead distance value exceeds the predetermined maximum look ahead distance value, the processor limits the look ahead distance value to the value of The predetermined maximum look ahead distance value.

6. An apparatus according to claim 1, wherein the fraction Time that varies with the sped of the aircraft is selected from The group consisting of a distance to runway look ahead distance value, a ground speed look ahead distance value, and a roll angle look ahead distance value.

7. A method for determining a look ahead distance value for use in a ground proximity warning system, wherein said method comprises selecting from a plurality of candidate look ahead distance values, a look ahead distance value representing a distance extending about an aircraft within which the ground proximity warning system provides ground proximity alerts, such That for aircraft speeds below a predetermined threshold speed the reaction time varies with the speed of the aircraft and for aircraft speeds at least as great as the predetermined threshold speed, the reaction time is constant and a constant reaction time look ahead distance value varies as the speed of the aircraft varies.

8. A method according to claim 7, wherein said speed of the aircraft is the ground speed of the aircraft.

9. A method according to claim 8 further comprising before said selecting step a step of generating the look ahead distance value for aircraft speeds at least as great as the predetermined threshold speed by multiplying the speed of the aircraft by a selected constant reaction time.

10. A method according to claim 9, wherein the selected constant reaction time is sixty seconds.

11. A method according to claim 7, further comprising after said selecting step the steps of:

comparing the selected took ahead distance value to a predetermined maximum look ahead distance value; and

limiting the look ahead distance value to the value of the predetermined maximum look ahead distance value, if the selected look ahead distance value exceeds the predetermined maximum look ahead distance value.

12. A method according to claim 7, wherein the look ahead distance value for aircraft speeds below a predetermined threshold speed is selected from the group consisting of a distance to runway look ahead distance value, a ground speed look ahead distance value, and a roll angle look ahead distance value.

13. A computer program product for determining a look ahead distance value for use in a ground proximity warning system, wherein the computer program product comprises:

a computer readable storage medium having computer readable program code means embodied in said medium, said computer-readable program code means comprising first computer instruction means for selecting from a plurality of candidate look ahead distance values, a look ahead distance value repenting a distance extending about an aircraft within which the ground proximity warning system provides ground proximity alerts, such that for aircraft speeds below a predetermined threshold speed, the reaction time varies within the speed of the aircraft and for aircraft speeds at least as great as the predetermined threshold speed, the reaction time is constant and a constant reaction time look ahead distance value varies as the speed of the aircraft varies.

14. A computer program product as defined in claim 13, wherein the speed of the aircraft is the ground speed of the aircraft.

15. A computer program product as defined in claim 14, wherein said computer-readable program code means further comprises second computer instruction means for generating the look ahead distance value for aircraft speeds at least as great as the predetermined threshold speed by multiplying the speed of the aircraft by a selected constant reaction time.

16. A computer program product as defined in claim 15, wherein the selected constant reaction time is sixty seconds.

17. A computer program product as defined in claim 13, wherein said computer-readable program code means further comprises:

third computer instruction means for comparing the selected look ahead distance value to a predetermined maximum look ahead distance value; and

fourth computer instruction means for limiting the look ahead distance value to the value of The predetermined maximum look ahead distance value, if the selected look ahead distance value exceeds die predetermined maximum look ahead distance value.

18. A computer program product as defined in claim 13, wherein the look ahead distance value for aircraft speeds below a predetermined threshold speed is selected from the group consisting a distance to runway look ahead distance value, a ground speed look ahead distance value, and a roll angle look ahead distance value.