METHOD AND DEVICE FOR DETERMINING A LINEAR TERRAIN PROFILE ALONG A LATERAL APPROACH TRAJECTORY OF AN AIRPORT

• US 20150317905A1
• Filed: 12/30/2014
• Published: 11/05/2015
• Est. Priority Date: 01/03/2014
• Status: Active Grant

• Current Assignee: Airbus Operations (European Aeronautic Defence and Space Company EADS NV)
• Original Assignee: Airbus Operations (European Aeronautic Defence and Space Company EADS NV)
• Inventors: Bourret, Thierry, AHUALLE HORIMOTO, Kenji
• Granted Patent: US 9,342,988 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01C 23/00 Combined instruments indicating more than one navigational value, e.g. for aircraft; Combined measuring devices for measuring two or more variables of movement, e.g. distance, speed or acceleration
• CPC Class Codes: G01C 5/005 altimeters for aircraft G01C5/02, G01C5/06 take precedence
• CPC Class Codes: G01C 5/06 by using barometric means
• CPC Class Codes: G01S 13/882 for altimeters measuring height using barometric means G01C5/06
• CPC Class Codes: G08G 5/0021 located in the aircraft
• CPC Class Codes: G08G 5/0086 for monitoring terrain radar or analogous systems specially adapted for terrain avoidance G01S13/935
• CPC Class Codes: G08G 5/025 Navigation or guidance aids radar or analogous systems specially adapted for landing purposes G01S13/913

Abstract

A device comprising a computation unit for computing, for each of a plurality of different distances relative to a threshold of a landing runway along a lateral approach trajectory, a geometric altitude, using a measured and stored barometric altitude, a computation unit for computing a terrain height, by subtracting, from the computed geometric altitude, a measured and stored height, and a computation unit for determining a terrain profile from the set of terrain heights computed for the set of different distances.

Claims

1. A method for determining a linear terrain profile along a lateral approach trajectory of an airport, comprising:

a first set of steps, comprising measuring, on at least one aircraft, automatically and repetitively, during at least one flight of the aircraft along the lateral approach trajectory, during an approach to a landing runway of the airport;

using at least one onboard radio altimeter, a height of the aircraft relative to the ground;

using at least one onboard barometric altimeter, a barometric altitude; and

using onboard sensors, a total air temperature and a Mach number of the aircraft; and

storing the measured values, automatically, in at least one memory; and

a second set of steps, implemented after the first set of steps and comprising, automatically, after the flight of the aircraft;

repetitively, for each of a plurality of different distances relative to a threshold of the landing runway along the lateral approach trajectory;

a) estimating, using the total air temperature, the Mach number and the barometric altitude, measured and stored in the memory, a variation of the static temperature dependent on the altitude and a temperature on the ground;

b) computing a geometric altitude, using the barometric altitude measured and stored in the memory, as well as the variation of the static temperature and of the temperature on the ground, estimated in step a);

c) computing a terrain height, by subtracting, from the geometric altitude computed in step b), the height measured by the radio altimeter and stored in the memory; and

for the set of the plurality of different distances relative to the threshold of the landing runway along the lateral approach trajectory;

d) determining at least one auxiliary terrain profile from the set of terrain heights computed for the set of different distances;

e) determining a terrain profile using at least the auxiliary terrain profile, the terrain profile representing the trend of the terrain height as a function of the distance relative to the threshold of the landing runway, the terrain height being defined relative to a reference altitude corresponding to that of the threshold of the landing runway; and

f) storing, in a database, the terrain profile determined in step e).

2. The method of claim 1,

wherein, in step b), the geometric altitude is computed using the following expression:

geometric altitude=

Hft=((Test/(Lest*0.3048))/(1−

((T0−

(L0·

Hbaro*0.3048))/T0)^Lest/L0)

in which;

geometric altitude is Hft;

Hbaro is the barometric altitude;

Lest is the estimate of the variation of the static temperature, as a function of the altitude;

L0 is a variation of the static temperature, as a function of the altitude of a standard atmosphere model;

Test is the estimated temperature on the ground; and

T0 is a reference temperature of the standard atmosphere model.

3. The method of claim 1,

wherein each distance relative to the threshold of the runway is computed by the integration of a so-called reference ground speed of the aircraft, dependent on a ground speed measured and stored during the first set of steps.

4. The method as claimed in claim 3,

comprising an additional step comprising:

computing a bias from computations of covariance between determined terrain profiles; and

adding this bias to the measured ground speed to obtain the reference ground speed, which is integrated.

5. The method of claim 1,

wherein, in step e), the terrain profile corresponds to the auxiliary terrain profile determined in step d).

6. The method of claim 1,

wherein the first set of steps and steps a) to d) of the second set of steps are implemented for a plurality of different approaches so that, for each of this plurality of approaches, an auxiliary terrain profile is determined in step d), and wherein step e) comprises computing, as terrain profile, the average of the auxiliary terrain profiles.

7. The method of claim 1,

wherein, for each distance considered, the barometric altitude and the height are referenced relative to a reference point located on the aircraft, using a correction using a value of the pitch angle of inclination of the aircraft, measured and stored during the first set of steps, and relative positions of the antennas.

8. A device for determining a linear terrain profile along a lateral approach trajectory of an aircraft, comprising:

at least one memory containing values measured on at least one aircraft, during at least one flight of the aircraft along the lateral approach trajectory, during an approach to a landing runway of the airport, namely;

a height of the aircraft relative to the ground, measured using at least one onboard radio altimeter;

a barometric altitude, measured using at least one onboard barometric altimeter; and

a total air temperature and a Mach number, measured using onboard sensors;

a first computation unit configured to estimate, for each of a plurality of different distances relative to a threshold of the landing runway along the lateral approach trajectory, using the total air temperature and the Mach number, stored in the memory, a variation of the static temperature dependent on the altitude and a temperature on the ground;

a second computation unit configured to compute, for each of the plurality of distances, a geometric altitude, using the barometric altitude stored in the memory, as well as the variation of the static temperature and of the temperature on the ground, estimated by the first computation unit;

a third computation unit configured to compute, for each of the plurality of distances, a terrain height, by subtracting, from the geometric altitude computed by the second computation unit, the height stored in the memory;

a fourth computation unit configured to determine at least one auxiliary terrain profile from the set of the terrain heights computed for the set of different distances;

a fifth computation unit configured to determine a terrain profile using at least the auxiliary terrain profile computed by the fourth computation unit, the terrain profile representing the trend of the terrain height as a function of the distance relative to the threshold of the landing runway, the terrain height being defined relative to a reference altitude corresponding to that of the threshold of the landing runway; and

a database, in which is stored the terrain profile determined by the fifth computation unit.