Off-path descent guidance by a flight management system

• US 5,739,770 A
• Filed: 01/16/1996
• Issued: 04/14/1998
• Est. Priority Date: 01/16/1996
• Status: Expired due to Fees

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Liden, Sam P.
• Primary Examiner(s): SWARTHOUT, BRENT
• Application Number:
  US08/586,264
• Time in Patent Office: 819 Days
• Field of Search: 340/971, 340/972, 340/976, 364/424.014, 364/424.013, 364/424.06, 364/430, 364/429, 364/439, 244/186, 244/187
• US Class Current: 340/976
• CPC Class Codes: G05D 1/0676 specially adapted for landing
• CPC Class Codes: G08G 5/0052 for cruising combined instruments indicating more than one navigational value G01C23/00
• CPC Class Codes: G08G 5/025 Navigation or guidance aids radar or analogous systems specially adapted for landing purposes G01S13/913

Abstract

A method for providing off-path guidance during a descent comprises the steps of determining a current altitude (H) and a corresponding current horizontal distance (X) of the aircraft from a selected bottom of descent point (B/D). A simulation of a Basic Descent Path (BDP) is performed, and a plurality of corresponding altitude (H_i) and horizontal distance (X_i) points is stored in a BDP array. A horizontal distance (X_B) is determined from the B/D point to a bottom point of the BDP array, and a horizontal distance (X_A) is determined in the BDP array that corresponds to the current aircraft altitude. A radius of a BDP circle is obtained by subtracting X_B from X_A for display on a navigation display unit. An aircraft symbol is displayed on the Navigation Display unit at a distance proportional to X_A, thereby indicating the distance remaining until to start of descent of the aircraft.

Claims

1. A method for providing off-path descent vertical guidance of an aircraft by a Flight Management System (FMS), comprising the steps of:

a) determining a current altitude (H) and a corresponding current horizontal distance (X) of the aircraft from a predetermined bottom of descent point (B/D);

b) determining if X is less than a predetermined distance X_s ;

c) if X is less than X_s performing a flight simulation of basic descent to produce a Basic Descent Path (BDP) starting at X, otherwise performing a descent simulation starting at a point where X is at or near X_s and using aircraft state data obtained from a previous flight plan prediction cycle;

d) storing a plurality of points, each of which corresponds to an altitude (H_i) and horizontal distance (X_i) in a basic descent path array of the BDP obtained from the flight simulation;

e) determining a horizontal distance (X_B) from the B/D point to a bottom point of the BDP array;

f) determining a horizontal distance (X_A) in the BDP array that corresponds to the current aircraft altitude;

g) subtracting X_B from X_A, thereby obtaining a radius around the B/D point of a BDP Circle and displaying this circle on the ND (Navigation Display) unit; and

h) displaying an aircraft symbol on the ND unit at a distance proportional to X_A from the B/D point, thereby indicating the distance remaining until to start of descent of the aircraft.