Patent Publication Number: US-2023137045-A1

Title: System for managing the deceleration of an aircraft on a runway on the ground and associated method

Description:
TECHNICAL FIELD OF THE INVENTION 
     The technical field of the invention is that of aircraft and more particularly that of systems for managing the deceleration of an aircraft on a runway on the ground. 
     The present invention relates to a system for managing the deceleration of an aircraft on a runway on the ground and in particular a system for managing the deceleration of an aircraft on a runway on the ground enabling the control in real time of the position of the aircraft on a braking axis of the runway. The present invention also relates to a control method implemented by the system. 
     TECHNOLOGICAL BACKGROUND OF THE INVENTION 
     Aircraft runway overruns are numerous, of the order of one runway overrun a month in the world, and are due, in around 25% of cases, to a poor piloting choice during a landing in degraded meteorological conditions. 
     Faced with this, the aeronautical authorities require solutions to be put in place to reduce the number of runway overruns, and in particular the number of longitudinal runway overruns. 
     Longitudinal runway overruns are linked to poor management of the braking means making it possible to brake the aircraft, when the conditions at the level of the runway are degraded. 
     At present, the different braking means are managed independently of one another and manually by the pilot, since all the braking means are not automated and since the automated braking means are not automated in a compatible manner. 
     Thus, it is the pilot who has to manage the configuration of each of the braking means. The risk of longitudinal runway overruns in the case of degraded meteorological conditions is thus high since the management of the braking means is entirely based on the pilot and his experience. 
     There thus exists a need for a system making it possible to manage the braking means of an aircraft in deceleration phase to limit the risk of a longitudinal runway overrun. 
     SUMMARY OF THE INVENTION 
     The invention offers a solution to the aforementioned problems, by proposing a system for managing the deceleration of an aircraft limiting the risk of longitudinal runway overruns. 
     A first aspect of the invention relates to a system for managing the deceleration of an aircraft on a runway on the ground enabling the control in real time of the position of the aircraft on a braking axis of the runway, comprising:
     Braking means configured to brake the aircraft;   A calculator configured to: 
   Calculate, from aircraft data and from external data comprising data on the state of the runway and meteorological data on the ground, a sequence of use of the braking means intended to brake the aircraft along the braking axis over a predetermined braking distance associated with a predetermined braking duration comprising a plurality of braking instants each associated with a predetermined position on the braking axis;   Update in real time the sequence of use as a function of the difference, along the braking axis, between the position of the aircraft and the predetermined position associated with a given braking instant or the occurrence of a given event;   
   Control means configured to control the braking means as a function of the sequence of use or an instruction sent by a runway overrun alert system of the aircraft.   

     Thanks to the invention, the calculator calculates a sequence of use of the braking means making it possible to brake the aircraft over a predetermined braking distance along a braking axis of the runway and which takes into account, on the one hand, the data of the aircraft and, on the other hand, the data relative to the state of the runway and to the meteorological conditions on the ground. The sequence of use is next updated when a difference along the braking axis between the position of the aircraft and the predetermined position for a given braking instant is noted, due for example to a difference between the external data used for the calculation and the real external data. This updating is carried out in real time, that is to say at very close instants, so that the difference does not have the time to be accentuated in such a way that it would no longer be possible to correct the position of the aircraft along the braking axis before a longitudinal runway overrun. The braking means are controlled by the control means according to the sequence of use in the nominal case or according to an alert instruction coming from a runway overrun alert system in an emergency. 
     Apart from the characteristics that have been set out in the preceding paragraph, the system according to a first aspect of the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations thereof. 
     According to an alternative embodiment, the braking means comprise a plurality of thrust reversers each equipped on an engine of the aircraft and a plurality of landing gears each comprising at least one wheel. 
     According to a sub-alternative embodiment compatible with the preceding alternative embodiment, the braking means further comprise a plurality of air brakes each equipped on a wing of the aircraft. 
     According to a first embodiment compatible with the preceding alternative embodiment, the control means comprise a single central controller. 
     Thus, the central controller is configured to control each braking means as a function of the sequence of use or an instruction. The number of calculators and thus the mass of the control means is minimised, which notably makes it possible to limit fuel consumption. 
     According to a second embodiment compatible with the preceding alternative embodiment, the control means comprise a central controller and a controller per braking means or per type of braking means. 
     Thus, each controller is configured to control a single braking means, for example a given thrust reverser, or a single type of braking means, for example all of the thrust reversers, and the central controller is configured to control each of the controllers as a function of the sequence of use or an instruction. It thus suffices to equip existing aircraft with a central calculator in order that the control system is implemented. 
     According to an alternative embodiment compatible with the preceding alternatives and embodiments, the aircraft comprises engines and in that the aircraft data comprise the speed of the aircraft and/or data of availability of the braking means and/or data of use of the engines. 
     Thus, the calculation of the sequence of use takes into account the current speed of the aircraft and the future speed of the aircraft, through information on the braking means which could be used and the use of the engines, and thus the level of deceleration of the aircraft. 
     According to a sub-alternative embodiment of the preceding alternative embodiment, the data of availability of a braking means comprise data relative to the state of the braking means and/or data relative to the cost of use of the braking means. 
     Thus, the calculation of the sequence of use takes into account the operating capacity of each braking means and/or its cost of use, for example through the wear that the use causes on the braking means and/or the consumption of fuel brought about by the use of the braking means. 
     According to an alternative embodiment compatible with the preceding alternatives and embodiments, the system comprises first communication means configured to communicate with a station on the ground. 
     Thus, the system can obtain external data from the control tower in charge of take offs and landings on the runway, in accordance with regulations. 
     According to an alternative embodiment compatible with the preceding alternatives and embodiments, the system comprises second communication means configured to communicate with at least one other aircraft. 
     Thus, the calculator can use sequences of use calculated by other aircraft having previously landed or taken off on the runway and having been transmitted to it to calculate the sequence of use. 
     A second aspect of the invention relates to a method for controlling in real time the position of an aircraft on a braking axis of a runway on the ground implemented by the system according to the first aspect of the invention, comprising the following steps:
     Calculating, by the calculator, from aircraft data and from external data comprising data on the state of the runway and meteorological data on the ground, a sequence of use of the braking means intended to brake the aircraft along the braking axis over a predetermined braking distance associated with a predetermined braking duration comprising a plurality of braking instants each associated with a predetermined position on the braking axis;   If, at a given braking instant, the difference along the braking axis, between the position of the aircraft and the predetermined position, is above a threshold or if a given event occurs, updating, by the calculator, of the sequence of use;   Implementing the sequence of use of the braking means by the control means.   

     Thus, the sequence of use is updated when the difference between the position of the aircraft and the predetermined position on the braking axis becomes greater than a threshold value at a given braking instant. 
     According to an alternative embodiment, the sequence of use is implemented automatically or manually. 
     Thus, the pilot may choose to implement the sequence of use himself. 
     According to an alternative embodiment compatible with the preceding alternative embodiment, the sequence of use is calculated in flight. 
     Thus, if the calculator does not manage to calculate a sequence of use corresponding to the predetermined braking distance, for example because the predetermined braking distance is too short given the speed of the aircraft and its braking means, the calculator can trigger an instruction for rejection of landing or take off. 
     A third aspect of the invention relates to a computer product-programme comprising instructions which, when they are executed by a computer, lead said computer to implement the steps of the method according to the second aspect of the invention. 
     A fourth aspect of the invention relates to a recording support readable by a computer comprising instructions which, when they are executed by a computer, lead said computer to implement the steps of the method according to the second aspect of the invention. 
     The invention and the different applications thereof will be better understood on reading the description that follows and by examining the figures that accompany it. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The figuresare presented for indicative purposes and in no way limit the invention. 
       -  FIG.  1    shows a schematic representation of an aircraft. 
       -  FIG.  2    shows a schematic representation of the control system according to the first embodiment. 
       -  FIG.  3    shows a schematic representation of the control system according to the second embodiment. 
       -  FIG.  4    is a block diagram illustrating the steps of the control method. 
       -  FIG.  5    shows a schematic representation of the position at several instants of an aircraft equipped with the control system, on a braking axis of a runway. 
     
    
    
     DETAILED DESCRIPTION 
     Unless stated otherwise, a same element appearing in the different figures has a single reference. 
     A first aspect of the invention relates to a system for managing the deceleration of an aircraft on a runway on the ground enabling the control in real time of the position of the aircraft on a braking axis of the runway on the ground. 
     The objective of the invention is to avoid an aircraft runway overrun, more particularly during the landing of the aircraft. The control system thus makes it possible to stop the aircraft before it overruns the runway, that is to say to respect a predetermined braking distance along a braking axis comprised in the runway. 
     “Braking distance” is taken to mean the distance travelled by the aircraft along a braking axis, between its landing on the runway and its stoppage on the runway, that is to say the distance travelled by the aircraft for a braking duration comprising a plurality of braking instants comprised between the instant at which the aircraft lands on the runway and the instant at which the aircraft stops on the runway. 
     The invention may also be implemented in the case of a rejection of take off, for example when the aircraft does not have sufficient speed to take off and has to brake urgently to prevent a runway overrun. The braking distance is then the distance travelled by the aircraft between the instant at which at least one first braking means is activated and the instant at which the aircraft stops on the runway. 
     The predetermined braking distance is the distance travelled by the aircraft along a braking axis, for a predetermined braking duration comprising a plurality of instants each associated with a predetermined position on the braking axis corresponding to the position at which the aircraft should be at the given braking instant in order that the aircraft stops at the predetermined braking distance. 
     [ FIG.  5   ] shows a schematic representation of the position at several braking instants, of an aircraft equipped with the control system, over a braking axis  402  on a runway  400 . 
     In  FIG.  5   , the predetermined braking distance  401  is along a longitudinal braking axis  402  passing through the middle of the runway  400  and is associated with a braking duration comprising 9 braking instants, each corresponding to a predetermined position X 1 ′, X 2 ′, X 3 ′, X 4 ′, X 5 ′, X 6 ′, X 7 ′, X 8 ′, X 9 ′ on the braking axis  402 . 
     In the case of landing, the predetermined braking distance  401  is for example the distance between the landing point of the aircraft on the runway  400  and the distance corresponding to a given percentage of the runway  400 , such as for example three quarters of the runway  400  or seven eighths of the runway  400 . 
     The predetermined braking distance  401  may also depend on the state of the runway  400 , for example zones being able to influence the braking of the aircraft, such as zones having hollows or bumps liable to slow down the aircraft or instead the coefficient of friction of the runway  400  supplied by a control tower on the ground. 
     The predetermined braking distance  401  is for example determined from performance abacuses of the aircraft  100  giving a braking distance as a function of the configuration of the braking means. 
     “Control in real time of the position of the aircraft on a braking axis” is taken to mean that the data relative to the position of the aircraft are processed immediately after their acquisition, and that the duration between the acquisition of the position data and the production of control instructions making it possible to adjust the real position of the aircraft on the predetermined position at a given braking instant is reduced to the minimum. The duration is for example of the order of 2.5 to 20 ms. 
     [ FIG.  2   ] shows a schematic representation of the control system  200  according to a first embodiment. 
     [ FIG.  3   ] shows a schematic representation of the control system  200  according to a second embodiment. 
     As illustrated in  FIG.  2   , the control system  200  comprises:
     Braking means  110 ;   A calculator  201  ;   Control means  210  comprising at least one central calculator  211 .   

     The braking means  110  are configured to brake the aircraft, that is to say to decrease the speed of the aircraft. 
     [ FIG.  1   ] shows a schematic representation of an aircraft  100 . 
     As illustrated in  FIG.  1   , the braking means  110  comprise a plurality of thrust reversers  111  and a plurality of landing gears  112 . The aircraft  100  comprises a plurality of engines  1110 . Each thrust reverser is mounted on an engine  1110  but each engine  1110  is not necessarily equipped with a thrust reverser  111 . The landing gear  112  comprises at least one wheel. 
     The aircraft  100  then comprises a first type of braking means  110  corresponding to the thrust reversers  111  and a second type of braking means  110  corresponding to the landing gears  112 . 
     The braking means  110  may also comprise a plurality of air brakes  113 , as in  FIG.  1   , each wing of the aircraft  100  being equipped with at least one air brake  113 . 
     The aircraft  100  then further comprises a third type of braking means  110  corresponding to the air brakes  113 . 
     The calculator  201  is configured to calculate a sequence of use of the braking means  110  making it possible to brake the aircraft  100  over the predetermined braking distance  401 . 
     “Sequence of use of the braking means  110 ” is taken to mean an ordered series of use of the braking means  110  comprising the activation/deactivation of the different braking means  110  and their characteristics of use, such as for example the use power for the thrust reversers  111 , the level of deceleration for the landing gears  112  or the angle for the air brakes  113 . 
     If the example is taken of an aircraft  100  landing at one end of a runway  400  and parking at the other end of the runway  400 , the sequence of use comprises for example, between the landing point of the aircraft  100  and the middle of the runway  400 , the use of thrust reversers  111  with a given first power and air brakes  113  according to a given angle, then, between the middle of the runway and the parking point, the use of the landing gears  112  with a given level of deceleration and the thrust reversers  111  with a given second power. 
     The sequence of use is for example calculated in flight before landing or at the moment of landing of the aircraft  100 , during the first contact between the runway  400  and the aircraft  100 . 
     The sequence of use is for example calculated on the ground at the moment of take off. 
     In the case where the sequence of use is calculated in flight, if the calculator  201  does not manage to calculate a sequence of use which does not lead to a runway overrun of the aircraft  100 , for example because the predetermined braking distance  401  is too short given the speed of the aircraft  100  and/or the braking means  110  of the aircraft  100 , the calculator  201  can generate an alert advising the pilot not to land. 
     The sequence of use is calculated from aircraft data, that is to say data relative to the aircraft, and external data, that is to say data relative to conditions external to the aircraft  100 . 
     The external data comprise data relative to the state of the runway  400 , for example the coefficient of friction of the runway  400 , and data relative to the meteorological conditions at the level of the runway  400 , for example the force and the direction of the wind. 
     The external data are for example obtained from a control tower on the ground in charge of the runway  400 . In this case, the system  200  comprises first communication means  2021  making it possible to communicate with the control tower and generally speaking with a station on the ground. 
     The aircraft data comprise for example the speed of the aircraft  100 , data relative to the availability of the braking means  110 , for example if a given braking means  110  is out of order or operational and/or data relative to the use by the aircraft  100  of its engines  1110 , for example the power delivered by each engine  1110 . 
     The data relative to the availability of a certain braking means  110  comprise data relative to the state of the braking means  110 , for example if the braking means  110  are operational or are out of order or instead the level of wear of the braking means  110 , and/or data relative to the cost of use of the braking means  110 , for example the consumption of fuel linked to the use of the braking means110 or instead the cost of replacing the braking means  110 . 
     The choice of the aircraft data used to calculate the sequence of use is for example made by the pilot or by the airline company. 
     The sequence of use may also be calculated from data coming from other aircraft  100 , for example aircraft  100  having already landed on the runway  400 . In this case, the system  200  comprises second communication means  2022  making it possible to communicate with other aircraft  100 . 
     The calculator  201  is also configured to update the sequence of use in real time as a function of the difference between the position of the aircraft  100  and the predetermined position  401  along the braking axis  402  at a given braking instant. 
     For example, if the example developed previously is reconsidered, if a wind pushes the aircraft  100  forwards with an intensity above the provided for intensity, that is to say above the intensity that had been used to calculate the sequence of use, the sequence of use is for example updated to compensate for the intensity of the wind, for example by increasing the power of the thrust reversers  111 . 
     The calculator  201  is also configured to update the sequence of use as a function of a given event. The event is for example the breakdown of a braking means  110  used in the sequence of use, or instead the breakdown of an engine  1110 . 
     The control means  210  are configured to control the braking means  110  as a function of the sequence of use or an instruction coming from a runway overrun alert system. 
     The runway overrun alert system is for example a ROAAS (Runway Overrun Alert and Awareness System) equipped on the aircraft  100 . 
     The instruction is for example to implement a maximum braking sequence when a danger has been detected. 
     According to the first embodiment of the system  200  illustrated in  FIG.  2   , the control means  210  comprise a single central controller  211  configured to control all of the braking means  110 . 
     According to the second embodiment of the system  200 , the control means  210  comprise a central controller  211  and a controller  212  per braking means  110  or per type of braking means  110  configured to control the braking means or the type of braking means on instruction of the central controller  211 . 
     In  FIG.  3   , the control means  210  comprise a central controller  211 , a controller  212 - 1  configured to control the thrust reversers  111 , a controller  212 - 2  configured to control the landing gears  112  and a controller  212 - 3  configured to control the air brakes  113 . 
     A second aspect of the invention relates to a method for controlling in real time the position of the aircraft on the braking axis  402  implemented by the system  200  according to the first aspect of the invention. 
     [ FIG.  4   ] is a block diagram illustrating the steps of the method  300  according to the second aspect of the invention. 
     A first step  301  of the method  300  implemented by the calculator  201 , consists in calculating the sequence of use of the braking means  110  as a function of aircraft data and external data. 
     If, for a braking instant of the predetermined braking duration, a first condition C 1  is realised, that is to say if the difference along the braking axis  402 , between the position X 1 , X 2 , X 3 , X 4 , X 5 , X 6 , X 7 , X 8 , X 9  of the aircraft  100  and the predetermined position X 1 ′, X 2 ′, X 3 ′, X 4 ′, X 5 ′, X 6 ′, X 7 ′, X 8 ′, X 9 ′ associated with the braking instant is above a threshold S1, a second step  302  of the method  300  is realised. 
     If the first condition C 1  is not realised, a third step  303  of the method is realised. 
     The threshold S1 is chosen in such a way that it is still possible to correct the position of the aircraft  100  on the braking axis  402  before a longitudinal runway overrun. 
     The threshold S1 is for example the value zero. 
     The second step  302  of the method  300  implemented by the calculator  201 , consists in updating the sequence of use. Thus, if for example, at a given braking instant, the position X 1 , X 2 , X 3 , X 4 , X 5 , X 6 , X 7 , X 8 , X 9  of the aircraft  100  is further on the runway than the predetermined position X 1 ′, X 2 ′, X 3 ′, X 4 ′, X 5 ′, X 6 ′, X 7 ′, X 8 ′, X 9  , for example because the intensity of the wind pushing the aircraft  100  forwards has been underestimated, the sequence of use is updated to brake the aircraft  100  more. 
     The second step  302  of the method  300  is followed by the third step  303 . 
     A third step  303  of the method  300  implemented by the control means  210 , consists in implementing the sequence of use on the braking means  110 . 
     The implementation of the sequence of use of the braking means  110  may be carried out automatically or manually by the pilot of the aircraft  100 . 
     In the case where the implementation is manual, indications could be provided to assist the pilot. 
     An exemplary embodiment is illustrated in  FIG.  5   . The position of an aircraft  100  along the braking axis  402  is represented therein at several instants, a point Xi corresponding to a position of the aircraft  100  at a given instant. 
     In  FIG.  5   , the aircraft  100  lands at a point X 1  of the runway  400 . The sequence of use of the braking means  100  has been calculated in flight to enable the aircraft  100  to brake over the predetermined braking distance  401 . 
     At each instant, it is verified if the first condition C 1  is realised. At the instant corresponding to the point X 2 , the difference between the position X 2  of the aircraft  100  and the predetermined position X 2 ′ along the braking axis  402  is below the threshold S1. The sequence of use is thus not updated and the control means  210  thus implement the sequence of use calculated in flight. 
     At the instant corresponding to the point X 3 , the difference along the braking axis  402  between the position X 3  of the aircraft  100  and the predetermined position X 3 ′ is above the threshold S1. The sequence of use is thus updated. From the instant corresponding to the point X 4 , the control means  210  implement the sequence of use updated at point X 3 . 
     Up to the instant corresponding to the point X 9 , parking point, the difference along the braking axis  402  between the position X 4 , X 5 , X 6 , X 7 , X 8 , X 9  of the aircraft  100  and the predetermined position X 4 ′, X 5 ′, X 6 ′, X 7 ′, X 8 ′, X 9 ′ is below the threshold S1 and the sequence of use is thus not updated between the instant corresponding to the point X 3  and the parking of the aircraft  100 .