METHOD FOR CHECKING THE APPROPRIATENESS OF A MASS VALUE OF AN AIRCRAFT

• US 20080065352A1
• Filed: 09/12/2007
• Published: 03/13/2008
• Est. Priority Date: 09/12/2006
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: COULMEAU, Francois
• Granted Patent: US 7,584,073 B2
• Time in Patent Office: Days
• US Class Current: 702/175
• CPC Class Codes: G01G 19/414 using electronic computing means only
• CPC Class Codes: G01M 1/125 of aircraft

Abstract

The field of the invention is that of checking the appropriateness of a mass value of an aircraft. The invention relates to a method for checking the appropriateness of an aircraft ground mass value M_s, communicated to a flight management system of the aircraft by a crew member of the aircraft or by an airline operating the aircraft, the communication taking place before a takeoff of the aircraft to perform a journey connecting a departure airport to a destination airport According to the invention, there are two checking phases; the first is a direct appropriateness check, based on a cross-check of independent information related to the mass of the aircraft. The second is an indirect appropriateness check, based on a comparison between values of performance parameters calculated on the basis of the mass value of the aircraft M_s and of the values of the same performance parameters provided by a constructor of the aircraft.

Claims

1. A method of checking the appropriateness of an aircraft ground mass value M_s, communicated to a flight management system of the aircraft by a crew member of the aircraft or by an airline operating the aircraft, the communication taking place before a takeoff of the aircraft to perform a journey connecting a departure airport to a destination airport, comprising the following two check phases:

a direct appropriateness check, based on a cross-check of independent information related to the mass of the aircraft;

said direct appropriateness check comprising the steps of;

performing a first estimation of a mass of fuel carried onboard the aircraft, EMC1;

performing a second estimation of a mass of fuel carried onboard the aircraft EMC2 including, evaluating a mass of fuel to be taken on board which allows the aircraft to make the journey separating the departure airport from the destination airport; and

an indirect appropriateness check, based on a comparison between values of performance parameters calculated on the basis of the mass value of the aircraft and of the values of the same performance parameters provided by a constructor of the aircraft.

2. The checking method as claimed in claim 1 wherein the direct appropriateness check further comprising:

determining an aircraft ground mass, with no fuel;

comparing the mass value and a first value, determined from a sum of the aircraft ground mass with no fuel and of the first estimation of onboard fuel mass, EMC1;

comparing the mass value and a second value, determined from a sum of the aircraft ground mass with no fuel, and of the second estimation of onboard fuel mass, EMC2;

when the absolute value of the difference between the mass value and the first value is greater than a threshold value, or when the absolute value of the difference between the mass value and the second value is greater than a second threshold value, triggering an alert destined for the crew.

3. The method as claimed in the claim 2 wherein the step of determining the aircraft ground mass with no fuel, comprises:

determining a type of the aircraft;

determining a configuration of the aircraft, the aircraft being able to have a cargo configuration or else a passenger transport configuration;

when the aircraft has the cargo configuration, determining an aircraft onboard freight mass;

when the aircraft has the passenger transport configuration, determining a number of passengers onboard the aircraft;

4. The method as claimed in claim 2, wherein, the first estimation of a mass of fuel carried onboard the aircraft, EMC1 is determined by evaluating a mass of fuel present aboard the aircraft by means of a fuel probe and a computer with which the aircraft is equipped.

5. The method as claimed in claim 2, wherein the second estimation comprises:

extracting from the flight management system of the aircraft;

the departure airport;

the destination airport;

a possible alternative airport;

a cruising altitude;

a cost index;

iteratively estimating a fuel mass at takeoff, termed the nominal mass, so that the aircraft should travel a first simplified profile, connecting the departure airport to the destination airport, the fuel consumption of the aircraft being minimized;

when an alternative airport is extracted from the flight management system iteratively estimating a fuel mass at takeoff, termed the backup mass, so that the aircraft should travel a second simplified profile, connecting the departure airport to the alternative airport, the fuel consumption of the aircraft being minimized;

estimating the fuel mass, EMC2 as being equal to a maximum between the nominal mass value and the backup mass value.

6. The method as claimed in claim 5, wherein the simplified profile is defined laterally by an orthodromy between a departure airport and an arrival airport and wherein the simplified profile is defined vertically by:

a first climb from the departure airport, from the ground up to a first altitude, performed at a speed, with a maximum thrust;

a second climb from the first altitude up to a speed limit altitude, performed at a first speed and a thrust identical to that adopted during the first climb;

a third climb from the speed limit altitude up to the cruising altitude, performed at a second speed and a thrust identical to that adopted during the first climb;

a cruising at the cruising altitude, performed at a third speed with a thrust adapted for maintaining the third speed constant;

a first descent from the cruising altitude down to a second altitude, performed at a fourth speed, with an idle thrust;

a second descent from the second altitude down to a third altitude, performed at a fifth speed, and a thrust adapted for maintaining the fifth speed constant;

a third descent to the arrival airport, from the second altitude down to the ground, under constant deceleration of the fifth.

7. The method as claimed in claim 5, wherein the estimation of the fuel mass, EMC2 takes into account, furthermore, a fuel reserve to forewarn of the vagaries arising during the journey separating the departure airport from the destination airport.

8. The method as claimed in claim 5, wherein the fuel mass estimation, EMC2 takes into account, furthermore, a fuel reserve to forewarn of a standby during the approach to the destination airport.

9. The method as claimed in claim 6, wherein the maximum thrust corresponds to 80% of the total thrust.

10. The method as claimed in claim 6, wherein the idle thrust corresponds to 20% of the total thrust.

11. The method as claimed in claim 1, the flight management system of the aircraft comprising a performance parameters database that is formulated by the constructor of the aircraft, wherein the indirect check comprises:

calculating a first suite of first values of performance parameters of the aircraft by considering the mass of the aircraft to be equal to the value;

extracting from the performance parameters database a second suite of second values of performance parameters of the aircraft corresponding to a configuration of the aircraft;

comparing the first suite and the second suite of values of performance parameters of the aircraft;

when the absolute value of one of the differences between a first value of the first suite and a second value of the second suite of one and the same performance parameter is greater than a threshold value, triggering an alert destined for the crew.

12. The method as claimed in claim 11, wherein a slat-flap configuration of the aircraft forms part of the entries of the performance parameters database.

13. The method as claimed in claim 11, wherein an aircraft takeoff runway altitude forms part of the entries of the performance parameters database.

14. The method as claimed in claim 11, wherein an aircraft takeoff runway length forms part of the entries of the performance parameters database.

15. The method as claimed in claim 11, wherein an aircraft takeoff runway temperature forms part of the entries of the performance parameters database.

16. The method as claimed in claim 11, wherein a runway takeoff stopping speed forms part of the performance parameters.

17. The method as claimed in claim 11, wherein a rotation speed is one of the performance parameters.

18. The method as claimed in claim 11, wherein a setpoint speed at takeoff for managing obstacles in the event of engine failure forms part of the performance parameters.

19. The method as claimed in claim 11, wherein an approach speed for landing forms part of the performance parameters.

20. The method as claimed in claim 2, wherein the first threshold has a value of less than 0.05 EMC1.

21. The method as claimed in claim 2, wherein the second threshold has a value of less than 0.15 EMC2.

22. The method as claimed in claim 2, wherein the third threshold has a value of less than 15 knots.