Method and device for determining a linear terrain profile along a lateral approach trajectory of an airport

• US 9,342,988 B2
• Filed: 12/30/2014
• Issued: 05/17/2016
• 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: Ahualle Horimoto, Kenji, Bourret, Thierry
• Primary Examiner(s): Jabr, Fadey
• Assistant Examiner(s): Martinez Borrero, Luis A
• Application Number:
  US14/586,461
• Publication Number:
  US 20150317905A1
• Time in Patent Office: 504 Days
• Field of Search: 701/14, 701/120, 701/4, 701/8, 701/116, 701/15, 701/300, 701/411, 701/416, 701/42, 701/16, 701/3, 701/1, 701/18, 701/17, 701/10, 701/436, 340/980, 340/947, 340/951, 340/970, 340/971, 340/967
• 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, the method comprising:

at a central processing unit (CPU) that is communicatively linked to a database and at least one memory;

receiving measured values that are automatically stored in the at least one memory, wherein the measured values are automatically and repetitively 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, and wherein the measured values comprise 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, a total air temperature and a Mach number of the aircraft measured using onboard sensors;

automatically, after the flight of the aircraft and after receiving the measured values;

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 at least one 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 at least one 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 at least one 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 one-dimensional 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 the 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 reference ground speed of the aircraft, dependent on a ground speed received and automatically stored in the at least one memory.

4. The method as claimed in claim 3, further 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 measuring the values received in the receiving step and steps a) to d) are implemented for a plurality of different approaches so that, for each of the plurality of approaches, an auxiliary terrain profile is determined in step d), and wherein step e) comprises computing, as a terrain profile, an 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 including a measured and stored value of the pitch angle of inclination of the aircraft received at the CPU, and relative positions of the antennas.

8. A device for determining a linear terrain profile along a lateral approach trajectory of an aircraft, the device 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, the measured values comprising;

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 at least one 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 different distances, a geometric altitude, using the barometric altitude stored in the at least one 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 different distances, a terrain height, by subtracting, from the geometric altitude computed by the second computation unit, the height stored in the at least one 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 one-dimensional 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 configured to store the terrain profile determined by the fifth computation unit.