Method for determining the speed of an aircraft

• US 8,340,843 B2
• Filed: 11/05/2009
• Issued: 12/25/2012
• Est. Priority Date: 11/07/2008
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Coulmeau, François, Gutierrez-Castaneda, Manuel, Simi, Nicolas, Blanchon, Xavier
• Primary Examiner(s): EL CHANTI, HUSSEIN A
• Application Number:
  US12/613,203
• Publication Number:
  US 20100152930A1
• Time in Patent Office: 1,146 Days
• Field of Search: 701/4, 701 7- 8, 701/14
• US Class Current: 701/14
• CPC Class Codes: G05D 1/0202 specially adapted to aircraft
• CPC Class Codes: G08G 5/0043 Traffic management of multiple aircrafts from the ground G08G5/003 takes precedence; data processing specially designed for resource management, e.g. scheduling or allocating time, human or machine resources G06Q10/06

Abstract

The invention relates to a method for determining the speed of an aircraft that is subject to a time constraint. The invention consists no longer in calculating a single CAS/MACH pair during climb/descent but in adapting the speed in a continuous manner to the bounds of curves of minimum V_min and maximum V_max speed defining a flight envelope of the aircraft. The calculation of these speeds is carried out on the basis of constant maximum and minimum speed setpoints and of a coefficient taking into account a deviation to the time constraint.

Claims

1. Method for determining the speed of an aircraft that is subject to a time constraint (RTA) expressed in the form of a fixed date at a determined point, the aircraft exhibiting a limit speed profile (V.sub.limit), the aircraft comprising a flight management system calculating a predicted time of arrival (ETA) of the aircraft at the point on following a speed setpoint expressed in the form of a pair of constant speeds (CAS,MACH), the flight management system calculating, furthermore, a first arrival time (ETA.sub.1) of the aircraft at the setpoint on following a pair of constant limit speeds (CAS.sub.limit,MACH.sub.limit), the aircraft following the first speed of the pair (CAS.sub.limit) when the aircraft flies at an altitude below a predefined altitude (Alt.sub.Max), the method comprising:

a. calculating a second arrival time (ETAenv.sub.2) according to the limit speed profile (V.sub.limit), the limit speed profile comprising a maximum speed and a minimum speed of the aircraft;

b. calculating a deviation (.DELTA..sub.ETA) to the time constraint;

.DELTA..sub.ETA=|ETA−

RTA|, the deviation to the time constraint .DELTA..sub.ETA being equal to the absolute value of the difference between the predicted arrival time ETA of the aircraft at the point on following a speed setpoint and the time constraint RTA;

c. calculating a first speed profile CAS(alt.sub.1) dependent on an altitude on the basis of the limit speed profile (V.sub.limit), with alt.sub.1 being an altitude between 0 and the predefined altitude (Alt.sub.Max);

d. calculating a second speed profile MACH(alt.sub.2) dependent on an altitude, on the basis of the limit speed profile (V.sub.limit), with alt.sub.2 being an altitude between the predefined altitude (Alt.sub.Max) and a cruising altitude

e. updating the predicted arrival time (ETA) by taking into account the calculated first and second speed profiles CAS(alt.sub.1) and MACH(alt.sub.2);

f. calculating the deviation (.DELTA..sub.ETA) of the time constraint;

.DELTA..sub.ETA=|ETA−

RTA|, the deviation to the time constraint .DELTA.sub.ETA being equal to the absolute value of the difference between the predicted arrival time ETA of the aircraft at the setpoint on following a speed setpoint and the time constraint RTA;

g. returning to the step of calculating the first speed profile CAS(alt.sub.1) if the deviation to the arrival time (.DELTA..sub.ETA) is nonzero, otherwise applying the calculated speed profiles to the aircraft.

2. Method for determining the speed of an aircraft according to claim 1, further comprising a step of calculating a coefficient (C) as a function of the deviation (.DELTA..sub.ETA) to the time constraint and in that if the deviation (.DELTA..sub.ETA) to the time constraint is nonzero, the return to the step (56,66) of calculating the first speed profile CAS(alt.sub.1).

3. Method for determining the speed of an aircraft according to claim 2, wherein the coefficient (C) is a piecewise function dependent on the altitude or on a distance to be traversed until the end of a flight phase where the speed setpoint is applied.

4. Method for determining the speed of an aircraft according to claim 2, wherein the coefficient (C) is a linear function dependent on at least one of the following values:

the deviation (.DELTA..sub.ETA) to the time constraint, the second arrival time (ETAenv.sub.2), the first arrival time (ETA.sub.1), the altitude of the aircraft, a distance to be traversed until the end of a flight phase where the speed setpoint is applied.

5. Method for determining the speed of an aircraft according to claim 1 wherein the limit speed profile (V.sub.limit) is a maximum speed profile (V.sub.max), the first arrival time (ETA.sub.1) being an arrival time (ETA.sub.Min) of the aircraft following a pair of constant maximum speeds (CAS.sub.Max,MACH.sub.Max), the second arrival time (ETAenv.sub.2) being an arrival time (ETAenv.sub.Min) following the maximum speed profile (V.sub.Max).

6. Method for determining the speed of an aircraft according to claim 5, wherein the coefficient (C) satisfies the following equation:

C=.DELTA.ETA/(ETA.sub.MIN−

ETAenv.sub.MIN).

7. Method for determining the speed of an aircraft according to claim 5, wherein the first speed profile CAS(alt.sub.1) calculated (57) satisfies the following equation:

CAS(alt.sub.1)=CAS.sub.MAX+C[V.sub.max(alt.sub.1)−

CAS.sub.max].

8. Method for determining the speed of an aircraft according to claim 5, wherein the second speed profile MACH(alt.sub.2) calculated satisfies the following equation:

MACH(alt.sub.2)=MACH.sub.MAX+C[V.sub.max(alt.sub.2)−

MACH.sub.max].

9. Method for deter lining the speed of an aircraft according to claim 5, wherein the time constraint is less than the second arrival time (ETAenv.sub.Min), the application of the maximum speed profile V.sub.max to the aircraft.

10. Method for determining the speed of an aircraft according to claim 1, wherein the limit speed profile (V.sub.limit) is a minimum speed profile (V.sub.Min), the first arrival time (ETA.sub.1) being an arrival time (ETA.sub.Max) of the aircraft following a pair of constant minimum speeds (CAS.sub.Min,MACH.sub.Min), the second arrival time (ETAenv.sub.2) being an arrival time (ETAenv.sub.Max) following the minimum speed profile (V.sub.min).

11. Method for determining the speed of an aircraft according to claim 10, wherein the coefficient (C) satisfies the following equation:

C=.DELTA.ETA/(ETAenv.sub.Max−

ETA.sub.Max).

12. Method for determining the speed of an aircraft according to claim 10, wherein the first speed profile CAS(alt.sub.1) calculated (67) satisfies the following equation:

CAS(alt.sub.1)=CAS.sub.min+C[CAS.sub.min−

V.sub.min(alt.sub.1)].

13. Method for determining the speed of an aircraft according to claim 10, wherein the second speed profile MACH(alt.sub.2) calculated satisfies the following equation:

MACH(alt.sub.2)=MACH.sub.min+C[MACH.sub.min−

V.sub.min(alt.sub.2)].

14. Method for determining the speed of an aircraft according to claim 10, wherein the time constraint is greater than the second arrival time (ETAenv.sub.Max) the application of the minimum speed profile V.sub.min to the aircraft.

15. A flight management system of an aircraft, comprising:

a. a module for constructing a continuous trajectory on the basis of points of a flight plan; and

b. a module of predictions for constructing a vertical profile optimized on the trajectory;

c. wherein the module for constructing and the module of prediction are configured to determine the speed of an aircraft that is subject to a time constraint (RTA) expressed in the form of a fixed date at a determined point, the aircraft exhibiting a limit speed profile (V.sub.limit), the aircraft comprising a flight management system calculating a predicted time of arrival (ETA) of the aircraft at the point on following a speed setpoint expressed in the form of a pair of constant speeds (CAS,MACH), the flight management system calculating, furthermore, a first arrival time (ETA.sub.1) of the aircraft at the setpoint on following a pair of constant limit speeds (CAS.sub.limit,MACH.sub.limit), the aircraft following the first speed of the pair (CAS.sub.limit) when the aircraft flies at an altitude below a predefined altitude (Alt.sub.Max) and performing the following;

i. calculating a second arrival time (ETAenv.sub.2) according to the limit speed profile (V.sub.limit), the limit speed profile comprising a maximum speed and a minimum speed of the aircraft;

ii. calculating a deviation (.DELTA..sub.ETA) to the time constraint;

.DELTA..sub.ETA=|ETA−

RTA|, the deviation to the time constraint .DELTA..sub.ETA being equal to the absolute value of the difference between the predicted arrival time ETA of the aircraft at the point on following a speed setpoint and the time constraint RTA;

iii. calculating a first speed profile CAS(alt.sub.1) dependent on an altitude on the basis of the limit speed profile (V.sub.limit), with alt.sub.1 being an altitude between 0 and the predefined altitude (Alt.sub.Max);

iv. calculating a second speed profile MACH(alt.sub.2) dependent on an altitude, on the basis of the limit speed profile (V.sub.limit), with alt.sub.2 being an altitude between the predefined altitude (Alt.sub.Max) and a cruising altitude

v. updating the predicted arrival time (ETA) by taking into account the calculated first and second speed profiles CAS(alt.sub.1) and MACH(alt.sub.2);

vi. calculating the deviation (.DELTA.sub.ETA) of the time constraint;

.DELTA..sub.ETA=|ETA−

RTA|, the deviation to the time constraint .DELTA.sub.ETA being equal to the absolute value of the difference between the predicted arrival time ETA of the aircraft at the setpoint on following a speed setpoint and the time constraint RTA; and

vii. returning to the step of calculating the first speed profile CAS(alt.sub.1) if the deviation to the arrival time (.DELTA..sub.ETA) is nonzero, otherwise applying the calculated speed profiles to the aircraft.