Method for reducing nuisance alarms for anti-collision with obstacles on aircraft

• US 7,826,971 B2
• Filed: 03/13/2008
• Issued: 11/02/2010
• Est. Priority Date: 03/13/2007
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Fontaine, Sylvain, Marty, Nicolas, Gamet, Pierre
• Primary Examiner(s): Nguyen; Cuong H
• Application Number:
  US12/047,633
• Publication Number:
  US 20090125236A1
• Time in Patent Office: 964 Days
• Field of Search: 701/3, 701/301, 701 7- 9, 342/29, 342/46, 342/455, 342/146, 342/147, 342/450, 342/454, 340/945, 340/969, 340/970
• US Class Current: 701/301
• CPC Class Codes: G05D 1/0646 to follow the profile of undulating ground

Abstract

A method for filtering anti-collision alarms for aircraft, the said aircraft comprising means for calculating its speed and extrapolated positions on its trajectory, the said extrapolated positions being calculated over a fixed maximum time period, called extrapolation time, and a topographical database of the terrain, the said database comprising, within a given perimeter, data on the density of obstacles, comprises a calculation of a weighting coefficient for the extrapolation time of the calculated extrapolated trajectories of the aircraft as a function of the density of obstacles within a surface area included within the perimeter.

Claims

1. Anti-collision method for aircraft, the aircraft includes:

means for calculating the speed of the aircraft;

means for calculating extrapolated positions of at least one trajectory of the aircraft, the said extrapolated positions being calculated for a fixed maximum time period, called extrapolation time; and

a topographical database of the terrain and of the obstacles, the said database comprising, within a given perimeter, obstacle density data;

Where said method comprises the calculation of a weighting coefficient for the extrapolation time of the extrapolated trajectories of the aircraft as a function of data on obstacle density within a given perimeter.

2. Method according to claim 1, wherein the calculation of the weighting coefficient of the extrapolation time comprises the determination of a height of the obstacles greater than a pre-determined minimum height.

3. Method according to claim 1, wherein the calculation of trajectory extrapolated positions of the aircraft over the extrapolation time comprises an estimation of at least three successive positions of the aircraft, of which:

a first position is determined by considering a first fixed time for reaction of the crew, a ground speed of the aircraft and a first heading;

a second position is determined as a function of a second period of time required in order to change the first heading of the aircraft towards a second heading;

and a third position is determined at a fixed heading for a third period of time referred to as climb duration.

4. Method according to claim 3, wherein, when an upper threshold for the density of obstacles is exceeded, a reduced climb duration is calculated from the product of the weighting coefficient and the third climb time.

5. Method according to claim 3, wherein the weighting coefficient is a function of the ground speed of the aircraft.

6. Method according to claim 3, wherein the weighting coefficient is a function of the differences in vertical speeds of the aircraft observed within a second fixed time period.

7. Method according to claim 6, wherein the second time period is around twenty seconds.

8. Method according to claim 3, wherein the weighting coefficient is a function of the height of the aircraft with respect to the ground.

9. Method according to claim 3, wherein the weighting coefficient is a function of the proximity of reference positions of obstacles identified from the topographical database.

10. Method according to claim 4, wherein the reduced duration is expressed in the following manner:

T<sub>CLIMB—

REDUCED</sub>=C·

T_CLIMB, where C is the weighting coefficient.

11. Method according to claim 10, wherein the weighting coefficient for the reduced duration is expressed in the following manner: