METHODS AND APPARATUS FOR CORRECTLY ADJUSTING BAROMETRIC PRESSURE SETTINGS ON BAROMETRIC ALTIMETERS

• US 20040186635A1
• Filed: 03/21/2003
• Published: 09/23/2004
• Est. Priority Date: 03/21/2003
• Status: Abandoned Application

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Manfred, Mark T.
• Application Number:
  US10/393,823
• Publication Number:
  US 20040186635A1
• Time in Patent Office: Days
• US Class Current: 701/4
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices
• CPC Class Codes: G01C 5/06 by using barometric means

Abstract

A method for detecting an inaccurate barometric pressure adjustment setting on a barometric altimeter is described. The method includes receiving a barometric corrected altitude from the altimeter, receiving an altitude from a global positioning satellite (GPS) system, comparing the barometric corrected altitude with the altitude received from the GPS system, actuating an alarm if the altitudes differ by an amount larger than a threshold value, the threshold value being dependent upon one or more of the received altitudes.

Claims

1. A method for detecting an inaccurate barometric pressure adjustment setting on a barometric altimeter, said method comprising:

receiving a barometric corrected altitude from the altimeter;

receiving an altitude from a global positioning satellite (GPS) system;

comparing the received barometric corrected altitude with the altitude received from the GPS system; and

actuating an alarm if the altitudes differ by an amount larger than a threshold value, the threshold value being dependent upon the received altitudes.

2. A method according to claim 1 further comprising correcting the barometric pressure adjustment setting on the barometric altimeter.

3. A method according to claim 2 wherein correcting the barometric pressure adjustment setting on the barometric altimeter is one of a manual adjustment or an automatic adjustment made by a flight management system.

4. A method according to claim 1 further comprising correcting the barometric pressure adjustment setting on the barometric altimeter until the alarm is de-actuated.

5. A method according to claim 1 wherein receiving a barometric corrected altitude comprises receiving the barometric altitude on a data bus.

6. A method according to claim 1 wherein receiving an altitude from a GPS system comprises receiving the GPS altitude on a data bus.

7. A method according to claim 1 wherein receiving an altitude from a GPS system comprises:

receiving pseudo-range data at the GPS from one or more GPS satellites; and

determining a GPS altitude based on the pseudo-range data.

8. A method according to claim 1 wherein receiving an altitude from a GPS system comprises:

receiving data at the GPS from one or more GPS satellites;

calculating a position of the aircraft based on the data; and

determining a GPS altitude based on the aircraft position.

9. A method according to claim 1 wherein receiving an altitude from a GPS system comprises receiving an altitude from at least one of a global navigation satellite system, a space based augmentation system, a ground based augmentation system, a wide area augmentation system, and a local area augmentation system.

10. A method according to claim 1 wherein actuating an alarm comprises communicating at least one of an audible or a visual alarm to a pilot.

11. A method according to claim 1 wherein receiving a barometric altitude comprises receiving a measured atmospheric pressure from the altimeter.

12. A method according to claim 11 wherein receiving an altitude from a GPS system further comprises determining an atmospheric pressure for a received GPS position based on a standard atmospheric model.

13. A method according to claim 12 further comprising:

adjusting the measured atmospheric pressure based on the barometric pressure adjustment setting; and

comparing the adjusted, measured atmospheric pressure to the determined atmospheric pressure based on the received GPS position and the standard atmospheric model.

14. A method according to claim 1 wherein comparing the received barometric altitude with the altitude received from the GPS system comprises setting the threshold value to a root sum square of a three sigma GPS altitude error, a baro-corrected altitude error, and an altitude of a runway at which landing is to occur.

15. A method according to claim 1 wherein comparing the received barometric altitude with the altitude received from the GPS system comprises compensating the received barometric altitude for temperature utilizing a static air temperature.

16. A method according to claim 1 wherein the threshold value further depends on one or more of an altitude of the aircraft above a runway at which the airplane will land, a distance to the runway, a barometric altitude, and a vertical integrity limit of the GPS altitude.

17. A method according to claim 1 further comprising filtering the barometric corrected altitude to remove noise from a barometric altitude signal.

18. An apparatus for detecting inaccurate barometric pressure adjustment settings on a barometric altimeter based on an altitude measured by a GPS system, said apparatus comprising:

a barometric altimeter configured to communicate a measured altitude, said altimeter comprising a module configured to allow a manual adjustment of a barometric pressure setting;

an alarm mechanism; and

a flight management system configured to receive the measured altitude from the GPS system and said barometric altimeter, said apparatus configured to determine a difference in the altitude received from the GPS system and said barometric altimeter, said apparatus configured to enable said alarm mechanism if the difference is greater than a threshold value, the threshold value being dependent upon altitudes received at said flight management system.

19. An apparatus according to claim 18 wherein said alarm mechanism comprises at least one of an audible alarm and a visual alarm.

20. An apparatus according to claim 18 wherein said flight management system is configured to supply data to said barometric altimeter which corrects the barometric pressure adjustment setting.

21. An apparatus according to claim 18 wherein said barometric altimeter communicates altitudes to said flight management system using a data bus.

22. An apparatus according to claim 18 wherein said flight management system causes said alarm mechanism to be actuated until the barometric pressure adjustment setting on the barometric altimeter is set to a setting which causes the differences in the altitudes received by said flight management system to be within the threshold value.

23. An apparatus according to claim 18 wherein to communicate a measured altitude, said altimeter transmits a measured atmospheric pressure to said flight management system, said flight management system configured to convert a measured atmospheric pressure to an altitude.

24. An apparatus according to claim 18 wherein to receive an altitude from the GPS system, said flight management system is configured to determine an atmospheric pressure for a received GPS position based on a standard atmospheric model.

25. An apparatus according to claim 18 wherein said flight management system is configured to set the threshold value to a root sum square of a three sigma GPS altitude error, a baro-corrected altitude error, and an altitude of a runway at which landing is to occur.

26. An apparatus according to claim 18 wherein said flight management system is configured to compensate the received barometric altitude utilizing a measurement of static air temperature.

27. An apparatus according to claim 18 wherein the threshold value is further dependent upon one or more of an altitude of the aircraft above a runway at which the airplane will land, a distance to the runway, corrected barometric altitude from said barometric altimeter, and a vertical integrity limit of the GPS system.

28. A computer program product used to detect inaccurate barometric pressure adjustment settings on a barometric altimeter, comprising:

a first computer code configured to receive altitude data from a GPS system;

a second computer code configured to receive altitude data from a barometric altimeter;

a third computer code configured to compare the received altitude data and determine if a difference between the two received altitudes is greater than a threshold value; and

a fourth computer code configured to cause an alarm to be actuated if the difference is greater than the threshold.

29. A computer program product according to claim 28 wherein said third computer code is configured to compare the difference in received altitudes to a threshold value, the threshold value being dependent upon one or more of the received altitudes.