Method for Determining the Speed of an Aircraft

• US 20100152930A1
• Filed: 11/05/2009
• Published: 06/17/2010
• Est. Priority Date: 11/07/2008
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Simi, Nicolas, Blanchon, Xavier, Gutierrez-Castaneda, Manuel, Coulmeau, Francois
• Granted Patent: US 8,340,843 B2
• Time in Patent Office: Days
• US Class Current: 701/7
• 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 said aircraft exhibiting a limit speed profile (V_limit), the said aircraft comprising a flight management system calculating a predicted time of arrival (ETA) of the aircraft at the said 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 (ETA₁) of the aircraft at the said point on following a pair of constant limit speeds (CAS_limit,MACH_limit), the aircraft following the first speed of the pair (CAS_limit) when the aircraft flies at an altitude below a predefined altitude (Alt_Max), the said method wherein:

the calculation of a second arrival time (ETAenv₂) on flying according to the limit speed profile (V_limit),

if the time constraint (RTA) lies between the first arrival time (ETA₁) and the second arrival time (ETAenv₂);

the calculation of a deviation (Δ

_ETA) to the time constraint;

Δ

_ETA=|ETA−

RTA|, the said deviation to the time constraint Δ

_ETA being equal to the absolute value of the difference between the predicted arrival time ETA of the aircraft at the said point on following a speed setpoint and the time constraint RTA,

the calculation of a first speed profile CAS(alt₁) dependent on an altitude on the basis of the limit speed profile (V_limit), with alt₁ being an altitude between 0 and the predefined altitude (Alt_Max),

the calculation of a second speed profile MACH(alt₂) dependent on an altitude, on the basis of the limit speed profile (V_limit), with alt₂ being an altitude between the predefined altitude (Alt_Max) and a cruising altitude,

the updating of the predicted arrival time (ETA) by taking into account the calculated first and second speed profiles CAS(alt₁) and MACH(alt₂),

the calculation of the deviation (Δ

_ETA) to the time constraint;

Δ

_ETA=|ETA−

RTA|, the said deviation to the time constraint Δ

_ETA being equal to the absolute value of the difference between the predicted arrival time ETA of the aircraft at the said point on following a speed setpoint and the time constraint RTA,

if the deviation to the arrival time (Δ

_ETA) is nonzero, the return to the step of calculating the first speed profile CAS(alt₁), otherwise the application of the calculated speed profiles to the aircraft.

2. Method for determining the speed of an aircraft according to claim 1, wherein a step of calculating a coefficient (C) as a function of the deviation (Δ

_ETA) to the time constraint and in that if the deviation (Δ

_ETA) to the time constraint is nonzero, the return to the step (56,66) of calculating the first speed profile CAS(alt₁).

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 (Δ

_ETA) to the time constraint, the second arrival time (ETAenv₂), the first arrival time (ETA₁), 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_limit) is a maximum speed profile (V_max), the first arrival time (ETA₁) being an arrival time (ETA_Min) of the aircraft following a pair of constant maximum speeds (CAS_Max,MACH_Max), the second arrival time (ETAenv₂) being an arrival time (ETAenv_Min) following the maximum speed profile (V_Max).

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

C=Δ

ETA/(ETA_MIN−

ETAenv_MIN)

7. Method for determining the speed of an aircraft according to claim 5, wherein the first speed profile CAS(alt₁) calculated (57) satisfies the following equation:

CAS(alt₁)=CAS_MAX+C·

[V_max(alt₁)−

CAS_max]

8. Method for determining the speed of an aircraft according to claim 5, wherein the second speed profile MACH(alt₂) calculated satisfies the following equation:

MACH(alt₂)=MACH_MAX+C·

[V_max(alt₂)−

MACH_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_Min), the application of the maximum speed profile V_max to the aircraft.

10. Method for determining the speed of an aircraft according to claim 1, wherein the limit speed profile (V_limit) is a minimum speed profile (V_Min), the first arrival time (ETA₁) being an arrival time (ETA_Max) of the aircraft following a pair of constant minimum speeds (CAS_Min,MACH_Min), the second arrival time (ETAenv₂) being an arrival time (ETAenv_Max) following the minimum speed profile (V_min).

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

C=Δ

ETA/(ETAenv_Max−

ETA_Max)

12. Method for determining the speed of an aircraft according to claim 10, wherein the first speed profile CAS(alt₁) calculated (67) satisfies the following equation:

CAS(alt₁)=CAS_min+C·

[CAS_min−

V_min(alt₁)]

13. Method for determining the speed of an aircraft according to claim 10, wherein the second speed profile MACH(alt₂) calculated satisfies the following equation:

MACH(alt₂)=MACH_min+C·

[MACH_min−

V_min(alt₂)]

14. Method for determining the speed of an aircraft according to one claim 10, wherein the time constraint is greater than the second arrival time (ETAenv_Max) the application of the minimum speed profile V_min to the aircraft.

15. Flight management system of an aircraft comprising a module for constructing a continuous trajectory on the basis of points of a flight plan and a module of predictions for constructing a vertical profile optimized on the trajectory, wherein the modules of predictions and for constructing a trajectory comprise means for implementing the method according to claim 1.