Method and avionics calculator for adapting an anchoring point of a terminal segment relative to a landing threshold point, for a non-precision approach

Abstract

- Method and avionics computer for adapting an anchor point of a terminal segment relative to a landing threshold point, for a non-precision approach. - The avionics computer includes a processing unit configured to compare the distance (D2) between a first position and a second position to a predetermined distance (dAP), the first position corresponding to the position of an initial anchor point (7) of an initial terminal segment (5A) and the second position corresponding to the position of a landing threshold point (LTP) of the runway (3), to check if the initial terminal segment (5A) of the virtual trajectory (TV) crosses the threshold (12) of the runway (3) and to determine if the distance (D2) between the first position and the second position is less than the predetermined distance (dAP) and if the initial terminal segment (5A) of the virtual trajectory (TV) crosses the threshold (12) of the runway (3),Define said landing threshold point (LTP) as the anchor point (AP) of a terminal segment of a virtual trajectory for a non-precision approach FLS mode, thereby increasing the availability of FLS mode implementation.

Description

technical field

[0001] The present invention relates to a method and an avionics computer for adapting an anchor point of a terminal segment of a virtual trajectory for a non-precision approach mode of type FLS of an aircraft, for the purpose of landing the aircraft on a runway of an aerodrome, as well as a method and a set of systems for implementing such a non-precision approach mode, comprising respectively such a method and such a device. State of the art

[0002] In the context of the present invention, "non-precision approach" means an approach that is not an instrument precision approach, such as, for example, an ILS ("Instrument Landing System") approach which uses, in particular, ground stations located at the edge of the runway and a specialized radio receiver mounted on board the aircraft.

[0003] A non-precision approach, such as that considered in the present invention, exists when the aforementioned equipment is not available or operational, at least partially, so that a conventional precision approach cannot be implemented. The present invention applies to a non-precision approach of the FLS type (for "FMS Landing System," where FMS stands for "Flight Management System," i.e., a landing system using a flight management system).

[0004] To implement this approach, using a non-precision approach mode such as FLS (Flight Leveling System), it is necessary to determine a virtual trajectory, corresponding to the theoretical path the aircraft should follow during the approach. Aircraft guidance then consists of attempting to eliminate any discrepancies between the aircraft's actual position and the position it would have if it were on this virtual trajectory. Typically, the virtual trajectory includes a terminal segment, namely the last segment before reaching the runway. This terminal segment is defined relative to a downstream extreme point called the anchor point.

[0005] The implementation of FLS mode provides significant assistance to the aircraft pilot, in particular by performing various guidance, monitoring and, if necessary, alerting operations.

[0006] However, for this FLS mode to be implemented up to the touch-down zone on the runway, the anchor point must be positioned correctly, particularly in relation to the runway threshold. Indeed, without this correct positioning, the FLS mode cannot be implemented up to the touch-down zone and its operation is halted at a certain distance from the runway.

[0007] However, depending on its determination, the anchor point is not always positioned as necessary for the implementation of an FLS mode.

[0008] This usual system for implementing a non-precision approach mode of the FLS type can therefore still be improved, particularly in terms of availability.

[0009] Furthermore, we know: by document CN 112 880 679 B, a method for generating a virtual FLS beam, based in particular on information relating to the positions of points FAF, MAP, LTP and FEP, the runway orientation, the height TCH and the angle FPA; by document US2004 / 183698 A1, a method and a device for determining a final approach axis of an aircraft for a non-precision approach, with a view to landing the aircraft on a runway; and by document CN 112 883 541 A, a method for calculating FLS deviation, which provides, during an approach and landing phase of an aircraft, for determining the deviation of the current position of the aircraft with respect to a virtual FLS beam that it must follow, using a spatial geometric relationship. Description of the invention

[0010] An objective of the present invention is to improve the implementation of a non-precision approach mode of the FLS type for an aircraft. To this end, it relates to a method for adapting an anchor point of a terminal segment of a virtual trajectory for a non-precision approach mode of the FLS type (or FLS mode) of an aircraft, with a view to landing the aircraft on a runway of an aerodrome, said method being implemented in an avionics computer, in particular a flight management system (or computer) of the FMS type (for "Flight Management System" in English), comprising at least one processing unit and a navigation database.

[0011] According to the invention, said process comprises at least the following steps, implemented by the processing unit: a comparison step consisting of comparing the distance between a first position and a second position to a predetermined distance, the first position corresponding to the position of an initial anchor point of an initial terminal segment and the second position corresponding to the position of a landing threshold point of said runway; a verification step consisting of checking whether the direction of the terminal segment of the virtual trajectory crosses the runway threshold; and a calculation step consisting, if the distance between the first position and the second position is less than said predetermined distance and if the initial terminal segment of the virtual trajectory crosses the runway threshold, of defining said landing threshold point as the anchor point.

[0012] Thus, thanks to the invention, when the aforementioned conditions are met, a suitable anchor point is defined, located on the threshold of the runway. This new positioning of the anchor point allows for the implementation of a FLS mode up to landing (i.e., up to a runway contact zone), thereby enabling the benefits (guidance, monitoring, alerting) of the FLS mode, detailed below, which would not have been possible without this adaptation.

[0013] It should be noted that this adaptation, i.e. this displacement of the anchor point, slightly shifts the anchor point laterally by a maximum of ten meters from the position of the initial anchor point, which is negligible in terms of implementation authorization and safety.

[0014] In a preferred embodiment, said predetermined distance is on the order of 0.14 nautical miles (approximately 260 meters).

[0015] The present invention also relates to a method of implementing a non-precision approach mode of type FLS of an aircraft, for the purpose of landing the aircraft on a runway of an aerodrome, said method using a virtual trajectory of which a terminal segment is defined with respect to an anchor point, said method being implemented by a set of avionics systems.

[0016] According to the invention, said method includes at least one method for adapting an anchor point as described above and it uses the anchor point determined by said avionics computer as the anchor point of the terminal segment of the virtual trajectory.

[0017] Advantageously, the said method implements, during the landing of the aircraft, guidance of the aircraft at least along the terminal segment of the virtual trajectory, up to a contact zone on the landing runway.

[0018] Furthermore, advantageously, the said method implements, during the landing of the aircraft, a monitoring of the aircraft up to a contact zone on the landing runway, so as to detect where appropriate at least one deviation (vertical and / or horizontal) of the current position of the aircraft with respect to the terminal segment of the virtual trajectory.

[0019] Furthermore, advantageously, said method emits, in the event of detection of a deviation (vertical and / or horizontal) greater than a predetermined value, at least one of the following alerts in the aircraft cockpit: a visual alert, an audible alert.

[0020] The present invention further relates to an avionics computer, in particular a flight management system (or computer), for adapting an anchor point of a terminal segment of a virtual trajectory for a non-precision approach mode of type FLS of an aircraft, with a view to landing the aircraft on a runway of an aerodrome, said avionics computer comprising at least one processing unit and a navigation database.

[0021] According to the invention, the processing unit is configured: to compare the distance between a first position and a second position to a predetermined distance, the first position corresponding to the position of an initial anchor point of an initial terminal segment and the second position corresponding to the position of a threshold point of said runway; to check if the terminal segment of the virtual trajectory crosses the threshold of the runway; and to, if the distance between the first position and the second position is less than said predetermined distance and if the initial terminal segment of the virtual trajectory crosses the threshold of the runway, define said runway threshold point as the anchor point.

[0022] The present invention also relates to a set of avionics systems for implementing a non-precision approach mode of type FLS of an aircraft, for the purpose of landing the aircraft on a runway of an aerodrome, said set comprising at least one flight management system configured to use a virtual final trajectory of which a terminal segment is defined with respect to an anchor point.

[0023] According to the invention, said assembly (of systems) comprises at least one avionics computer for adapting an anchor point as described above, and said assembly (of systems) is configured to use the anchor point defined by said avionics computer as the anchor point of the terminal segment of the virtual trajectory.

[0024] In a preferred embodiment, said assembly further comprises at least one of the following systems: a flight warning system, a flight guidance system, a terrain warning and avoidance system, and it is configured to implement at least one of the following actions upon landing of the aircraft: aircraft guidance at least along the terminal segment of the virtual trajectory, up to a contact zone on the runway; aircraft monitoring up to the contact zone on the runway, so as to detect any deviation (vertical and / or horizontal) of the aircraft's current position relative to the terminal segment of the virtual trajectory; in the event of detection of a deviation (vertical and / or horizontal) greater than a predetermined value, the issuance of at least one of the following alerts in the aircraft cockpit: a visual alert, an audible alert.

[0025] Furthermore, the present invention also relates to an aircraft, in particular a transport aircraft, which includes at least one avionics computer and / or at least one set of systems, such as those described above. Brief description of the figures

[0026] The accompanying figures will clearly illustrate how the invention can be implemented. In these figures, identical reference numerals designate similar features. figure 1 is the block diagram of a particular embodiment of a system for implementing a FLS mode, comprising an avionics computer for adapting an anchor point of a terminal segment of a virtual trajectory. figure 2 is a schematic view in a horizontal plane of an adaptation of an anchor point of a terminal segment of a virtual trajectory that is aligned with the axis of the landing runway. figure 3is a schematic view in a horizontal plane of an adaptation of an anchor point of a terminal segment of a virtual trajectory that is laterally offset from the runway axis. figure 4 is the synoptic diagram of a particular embodiment of a method for implementing a FLS mode, comprising a process for adapting an anchor point of a terminal segment of a virtual trajectory. figure 5 is a schematic perspective view of a terminal segment of a virtual trajectory followed by an aircraft during an approach, in preparation for landing the aircraft on a runway. figure 6 schematically illustrates a display, particularly a vertical one, relating to the situation of the figure 5 . There figure 7 schematically illustrates a horizontal display relating to the situation of the figure 5 . Detailed description

[0027] Avionics computer 1, shown schematically on the figure 1 and allowing to illustrate the invention, is intended to adapt an anchor point of a terminal segment of a virtual trajectory, as specified below.

[0028] In a preferred embodiment, this avionics computer 1 corresponds to a flight management system (or computer) of type FMS (“Flight Management System” in English) of an AC aircraft, for example a transport aircraft.

[0029] In a preferred application, this avionics computer 1 is part of a set 2 of systems, intended for the implementation of a non-precision approach mode of type FLS (hereafter referred to as "FLS mode") of the aircraft AC.

[0030] In the examples of figures 2, 3 And 5 , aircraft AC equipped with said set 2 (of systems) is in the approach phase to a runway 3 of an aerodrome 4, with a view to landing on this runway 3.

[0031] Set 2 allows, in the usual way, and as further explained below, the determination of a (final) virtual trajectory TV and its following by the aircraft AC for the implementation of an FLS mode, with a view to the landing of the aircraft AC on the landing runway 3. As also explained below, set 2 determines the (possible) lateral and vertical deviations of the current position PC of the aircraft AC with respect to this virtual trajectory TV (or virtual approach axis), and the aircraft AC is then piloted in such a way as to cancel these deviations.

[0032] Assembly 2 (which is carried on the AC aircraft, as very schematically represented on the figures 2, 3 And 5 ) is therefore intended to assist the pilot of the AC aircraft, in particular to implement the FLS mode along the virtual TV trajectory.

[0033] This virtual flight path TV includes a terminal segment 5. This terminal segment 5 corresponds to a straight line segment which, in the direction (illustrated by an arrow F) of the aircraft AC's flight during the approach, begins at a FAF (for "Final Approach Fix") point, that is, an upstream point representing a final approach point or landmark, and has a specific slope, generally on the order of 3°. In the following description, the terms "upstream" and "downstream" are defined relative to the direction of flight of the aircraft AC, indicated by the arrow F on the figures 3 to 5 .

[0034] Terminal segment 5 ends at a downstream point representing an AP anchor point (or "anchor point" in English).

[0035] The avionics computer 1 is designed to adapt, under certain conditions, the AP anchor point of the terminal segment 5 and to provide it to assembly 2 so that it can use it to implement the FLS mode.

[0036] To do this, the avionics computer 1 includes at least, as shown on the figure 1 : a navigation database 6 of type NDB (for "Navigation Data Base" in English); and a processing unit 8 (PROCESS for "Processing Unit" in English) configured, in particular, to receive data from the navigation database 6 and to perform processing from this data.

[0037] More specifically, processing unit 8 is configured: to calculate the distance D1, D2 ( figures 2 and 3) between the position of an initial anchor point 7 (of a terminal segment called initial 5A defined between this initial anchor point 7 and the FAF point) and the position of a landing threshold point LTP (or LTP point) of said runway 3, and to compare this distance D1, D2 to a predetermined distance dAP; to check if the initial terminal segment 5A crosses the threshold 12 of runway 3; and to, if said distance D1, D2 is less than said distance dAP and if the terminal segment 5A crosses the threshold 12 of runway 3, define said LTP point as the AP anchor point.

[0038] To implement FLS mode, assembly 2 includes, in addition to the avionics computer 1, a plurality of standard systems grouped in a sub-assembly 9 on the figure 1 Subset 9 comprises the following common systems: a flight warning system 10, for example of type FWS (for “Flight Warning System” in English), enabling in particular the determination of excessive deviations and highlighting them on at least one screen; a flight guidance system 11, for example of type FG (for “Flight Guidance” in English); and a terrain avoidance and warning system 13, for example of type TAWS (for “Terrain Avoidance and Warning System” in English).

[0039] To implement the FLS mode, assembly 2 can also use other common systems or means grouped in a subset 14 on the figure 1 Subset 14 comprises the following systems: a multimode landing aid receiver 15, for example of the MMR (Multi Mode Receiver) type; an inertial and air data reference system 16, for example of the ADIRS (Air Data and Inertial Reference System) type; a display system 17 (DISPLAY) including, in particular, a primary flight parameter display 19 of the PFD (Primary Flight Display) type, as shown for example on the figure 6 and a 20-inch ND-type navigation screen (for "Navigation Display"), as shown for example on the figure 7 ; and a sound alarm unit 21 (SOUND for "sound alarm unit" in English) including, for example, at least one loudspeaker which is installed in the aircraft cockpit or in cockpit equipment and which enables the emission of a sound alarm.

[0040] In a preferred embodiment, and as described in more detail below, set 2 (of systems) is configured to implement the following actions upon landing of the AC aircraft: guidance of aircraft AC at least along the terminal segment 5 of the virtual trajectory TV, up to a contact zone 18 on the runway 3. To do this, the display system 17 can provide information to the pilot, in order to help guide aircraft AC to its landing on the runway 3; monitoring of aircraft AC up to the contact zone 18 on the runway 3, so as to detect where appropriate a deviation (vertical and / or horizontal) of the current position PC of aircraft AC with respect to the initial terminal segment 5A of the virtual trajectory TV; and in the event of detection of a vertical deviation greater than a predetermined value, the emission of at least one alert (or alarm) in the aircraft cockpit, namely at least one visual alert (for example on the primary flight parameters screen 19) and / or at least one audible alert (in particular using the audible alert system 21).

[0041] The avionics computer 1, as described above, is intended to implement a process P (represented on the figure 2 ) adaptation of an anchor point AP of a terminal segment 5 of a virtual trajectory TV for an FLS mode of an aircraft AC, for the purpose of landing the aircraft AC on a runway 3 of an aerodrome 4, as illustrated in the figures 3 to 5 . Terminal segment 5 begins at the final approach point FAF and ends at the anchor point AP.

[0042] For its implementation, process P is part of a method M ( figure 2 ) implementation, by assembly 2 as described above, of an FLS mode which uses the anchor point AP defined by said process P as the anchor point of the terminal segment 5 of the virtual trajectory TV during the implementation of the FLS mode.

[0043] Process P comprises, as shown in the figure 4including a comparison step E1, a verification step E2 and a calculation step E3.

[0044] The P process takes into account the position (namely latitude, longitude, and altitude) of the initial anchor point 7.

[0045] The initial anchor point 7 (which represents the anchor point considered by assembly 2 before the adaptation implemented by the avionics computer 1) can correspond to the MAP point (specified below) or to a point determined by a usual calculation means (in particular the avionics computer 1) of assembly 2. This initial anchor point 7 then represents a "pseudo-FEP", that is to say a point presenting the characteristics of an FEP point (for "Final End Point" in English) but which has not been coded as an FEP point but determined by a calculation means of assembly 2.

[0046] The P process also takes into account the position (namely latitude, longitude, and altitude) of the landing threshold point LTP (hereafter LTP point) of runway 3. The LTP (for "Landing Threshold Point" in English) which is recorded in the navigation database 6, is a point located laterally at the intersection between the threshold 12 (i.e. the upstream edge of runway 3, which is orthogonal to the axis 3A of runway 3 and which has a length equal to the width L of runway 3) of runway 3 and the axis 3A of runway 3, and vertically at a runway threshold height TCH (for "Threshold Crossing Height" in English). This TCH height is either coded in the navigation database 6, or recorded in a memory of the avionics computer 1, generally being equal to 50 feet (about 15 meters) in this case.

[0047] The E1 comparison step, implemented by processing unit 8, consists of: to calculate the distance D1, D2 between the position of the initial anchor point 7 and the position of the LTP point; and to compare this distance D1, D2 to a predetermined distance dAP.

[0048] In a preferred embodiment, the predetermined dAP distance is on the order of 0.14 nautical miles (about 260 meters).

[0049] In addition, the E2 verification step, also implemented by the processing unit 8, consists of checking whether the direction of the initial terminal segment 5A of the virtual trajectory TV crosses the threshold 12 of track 3.

[0050] Within the framework of the present invention, it is considered that the direction of the initial terminal segment 5A crosses the threshold 12, when the direction of the initial terminal segment 5A (i.e. the initial terminal segment 5A or the upstream extension of the initial terminal segment 5A) crosses a vertical plane of width equal to the width L of the landing runway 3 and which passes through the threshold 12 of the landing runway 3.

[0051] Therefore, the aforementioned condition (the direction of the terminal segment 5A crosses the threshold 12) is met if, laterally, the initial anchor point 7 is offset, at most, by a distance L / 2 from the point LTP.

[0052] The calculation step E3, implemented by the processing unit 8, consists of adapting the anchor point AP if the two aforementioned conditions, verified respectively in the comparison step E1 and the monitoring step E2, are met simultaneously: the distance D1, D2 is greater than the predetermined dAP distance; and the initial terminal segment 5A of the virtual trajectory TV crosses the threshold 12 of runway 3.

[0053] If these two conditions are met, the calculation step E3 defines the said LTP point as the AP anchor point (and this instead of the initial anchor point 7).

[0054] THE figures 2 and 3 present two particular examples to illustrate this movement of the AP anchor point (from the initial anchor point 7 to the LTP point).

[0055] In the first example shown on the figure 2 , the projection onto the ground of the initial terminal segment 5A is aligned with the axis 3A of the landing runway 3.

[0056] In this example, the aforementioned conditions are indeed met. On the one hand, the projection of the extension of the initial terminal segment 5A does indeed intersect the threshold 12 of track 3. On the other hand, the distance D1 between the initial anchor point 7 and the point is indeed less than the distance dAP.

[0057] On the figures 2 and 3 We have represented, in dashes, a circle C with center LTP and radius dAP. All points located in this circle C therefore satisfy this last condition.

[0058] In this first example, the AP anchor point determined by the avionics computer 1 therefore corresponds to the LTP point and the terminal segment 5 (between the points FAF and AP) is aligned with the initial terminal segment 5A (between the points FAF and 7).

[0059] Depending on the position, the initial anchor point may sometimes correspond to a Missed Approach Point (MAP), or MAP point, relative to runway 3. The published MAP point is the latest point at which the pilot must initiate a go-around when the corresponding approach is missed (which is notably the case when the pilot cannot see runway 3 before arriving at this MAP point). On the figures 2 and 3 , we have represented the point MAP as an illustration.

[0060] Furthermore, in the second example shown on the figure 3 , the projection onto the ground of the initial terminal segment 5A presents an angle α with respect to the axis 3A of the landing runway 3.

[0061] In this example, the aforementioned conditions are also met. On the one hand, the projection of the extension of the initial terminal segment 5 does indeed intersect the threshold 12 of runway 3. On the other hand, the distance D2 between the initial anchor point 7 and the LTP point is indeed less than the distance dAP.

[0062] In this second example, the AP anchor point determined by avionics computer 1 therefore also corresponds to the LTP point.

[0063] In this case, the terminal segment 5 (of the virtual trajectory TV) followed by the aircraft AC (which ends at this anchor point AP) is parallel to the initial terminal segment 5A linking the point FAF to the initial anchor point 7, being offset (laterally) by a lateral offset DEV.

[0064] In this example, the terminal segment 5 of the virtual trajectory TV, which is followed by aircraft AC, is thus slightly offset laterally (i.e., in the horizontal plane) relative to the initial terminal segment 5A. This lateral offset DEV is less than or equal to half the width L of runway 3; otherwise, the initial terminal segment 5 would not cross the threshold 12 of runway 3. This lateral offset DEV is therefore small, generally less than 0.01 NM (approximately 18.5 meters), and is negligible (in particular, having no negative impact on safety and not prohibiting its implementation).

[0065] Terminal segment 5 has the same slope as the initial terminal segment 5A and it leads to the anchor point AP.

[0066] Furthermore, as indicated above, method M, which implements the FLS mode using set 2 (of systems), includes the method P for adapting the AP anchor point as described above, and it uses the AP anchor point determined by the method P as the anchor point of the terminal segment 5 of the virtual trajectory TV.

[0067] To do this, when the FLS mode is active, namely during the approach of the AC aircraft and the landing of the AC aircraft, up to the contact zone 18 of the landing runway 3, the method M implements (using assembly 2) different steps or operations specified below.

[0068] Method M includes a continuously implemented guidance step (or operation) EA, which guides aircraft AC along the terminal segment 5 of the virtual trajectory TV, up to the contact zone 18 on runway 3.

[0069] The guidance of the aircraft AC consists of canceling any deviations (which are continuously detected) between the current position PC of the aircraft AC, determined as specified below, and the position it would have if it were on the virtual trajectory TV. For example, the figure 7 , aircraft AC is vertically offset by a PDEz offset, being located below the virtual trajectory TV.

[0070] The display system 17 shows these discrepancies (or deviations) on screens that are installed in the cockpit of the AC aircraft.

[0071] The display system 17 includes, for example, the primary flight parameter screen 19 of type PDF (for "Primary Flight Display"), shown on the figure 6 , and the ND-type navigation screen 20 (for "Navigation Display"), shown on the figure 7 .

[0072] Screen 19 typically includes a flight indicator 22, a heading indicator 23, an altitude indicator 24 and a speed indicator 25.

[0073] When FLS mode is implemented, the display system 17 shows, in particular, the following information on screen 19: on a Z1 zone, an indication (“FLS”) informing that the FLS mode is active; on a Z2 zone, the references (not shown) of the anchor point (LTP point) used by the FLS mode; and on a Z3 zone, the “FG / S” and “F-LOC” modes which are activated, i.e. respectively for horizontal guidance (“glide”) and vertical guidance (“loc”) with respect to the virtual trajectory TV.

[0074] In a particular embodiment, the terrain 13 alert and avoidance system activates, where appropriate, the “FG / S” and “F-LOC” modes.

[0075] Flight indicator 22 indicates that aircraft AC is located below the virtual trajectory, as in the example of the figure 5 .

[0076] In addition, the display system 17 also includes the navigation screen 20 which typically features, as shown on the figure 7 , a heading indicator 26, a distance indicator 27 and an IAC symbol illustrating the aircraft's current position.

[0077] In the example shown, relating to the situation of the figure 5 The aircraft AC is correctly positioned laterally. In this case, the IAC symbol that follows the virtual trajectory (illustrated by an ITV symbol) is directed towards the landing runway (illustrated by an I3 symbol).

[0078] In a particular embodiment, the current position PC of the aircraft AC, which is used for guidance, is determined by the processing unit 8 of the avionics computer 1 (flight management system). To do this, the processing unit 8 typically performs a consolidation: on the one hand, raw GNSS (for "Global Navigation Satellite System" in English) position data received from the multimode landing aid receiver 15; and on the other hand, hybridized position data, from GNSS and inertial data, received from the inertial reference system and air data 16.

[0079] In addition, said method M also includes a monitoring step EB, implemented continuously, consisting, upon landing of aircraft AC, of ​​monitoring aircraft AC up to the contact zone 18 on landing runway 3.

[0080] This EB monitoring step is able to detect, if necessary, a deviation, such as the vertical deviation PDEz of the figure 5 , of the current position PC of the aircraft AC with respect to the terminal segment 5 of the virtual trajectory TV.

[0081] Furthermore, the M method includes an EC alert step consisting, in the event of detection (in the EB monitoring step) of a vertical deviation and / or a horizontal deviation which is greater than a predetermined value, of issuing one or more alerts in the aircraft cockpit.

[0082] To alert the pilot of such an excessive deviation situation, the sound alert unit 21 emits an audible signal in the cockpit of the aircraft AC.

[0083] In addition, the display unit 17 emits on the screen 19 at least one characteristic symbol 28, preferably flashing, to alert the aircraft pilot of this excessive deviation.

[0084] To do this, depending on the envisaged architecture of assembly 2, the flight alert system 10 or the flight guidance system 11 provides instructions to the display system 17 to carry out such a display.

[0085] The avionics computer 1 and the P method (as well as assembly 2 and method M, which use the anchor point determined by the avionics computer 1 and the P method), as described above, offer numerous advantages. In particular, they offer the following advantages: in terms of availability, since they allow the anchor point to be adapted in such a way as to enable the implementation of FLS mode (up to the contact zone on the runway, with its guidance, monitoring and possibly alerting operations) for situations which do not currently allow it; in terms of robustness; and by providing information that could be used, if necessary, in a future automatic landing system for straight and non-offset approaches.

Claims

1. A method for adapting an anchor point of a terminal segment of a virtual path for a non-precision FLS approach mode of an aircraft, with a view to landing the aircraft (AC) on a runway (3) of an aerodrome (4), said method (P) being implemented in an avionics computer (1), in particular a flight management system, comprising at least a processing unit (8) and a navigation database (6), characterized in that it comprises at least the following steps, implemented by the processing unit (8) of the avionics computer (1): - a comparison step (E1), consisting in comparing the distance (D1, D2) between a first position and a second position with a predetermined distance (dAP), the first position corresponding to the position of an initial anchor point (7) of an initial terminal segment (5A) and the second position corresponding to the position of a landing threshold point (LTP) of said runway (3); - a checking step (E2), consisting in checking whether the direction of the terminal segment (5A) of the virtual path (TV) crosses the threshold (12) of the runway (3); and - a computing step (E3), consisting, if said distance (D1, D2) between the first position and the second position is less than said predetermined distance (dAP) and if the initial terminal segment (5A) of the virtual path (TV) crosses the threshold (12) of the runway (3), in defining said landing threshold point (LTP) as an anchor point (AP).

2. The method as claimed in claim 1, characterized in that said predetermined distance (dAP) is of the order of 0.14 nautical miles.

3. A procedure for implementing a non-precision FLS approach mode of an aircraft, with a view to landing the aircraft (AC) on runway (3) of an aerodrome (4), said procedure (M) using a virtual path (TV) comprising a terminal segment (5) that is defined with respect to an anchor point (AP), said procedure (M) being implemented by a set (2) of avionics systems (1, 10, 11, 13, 15, 16, 17, 21), characterized in that it comprises at least a method (P) for adapting an anchor point (AP) as claimed in either of claims 1 and 2, and in that it uses, where applicable, the anchor point (AP) defined by said method (P) as an anchor point of the terminal segment (5) of the virtual path (TV).

4. The procedure as claimed in claim 3, characterized in that, during the landing of the aircraft (AC), it guides the aircraft (AC) at least along the terminal segment (5) of the virtual path (TV), as far as a touchdown zone (18) on the runway (3).

5. The procedure as claimed in either of claims 3 and 4, characterized in that, during the landing of the aircraft (AC), it monitors the aircraft (AC) as far as a touchdown zone (18) on the runway (3), so as to detect, where applicable, at least one deviation (PDEz) of the current position (PC) of the aircraft (AC) with respect to the terminal segment (5) of the virtual path (TV).

6. The procedure as claimed in claim 5, characterized in that, in the event of detection of a deviation (PDEz) greater than a predetermined value, it emits at least one of the following warnings in the cockpit of the aircraft (AC): a visual warning, an acoustic warning.

7. An avionics computer, in particular a flight management system, for adapting an anchor point of a terminal segment of a virtual path for a non-precision FLS approach mode of an aircraft, with a view to landing the aircraft (AC) on a runway (3) of an aerodrome (4), said avionics computer (1) comprising at least a processing unit (8) and a navigation database (6), characterized in that the processing unit (8) is configured: - to compare the distance (D1, D2) between a first position and a second position with a predetermined distance (dAP), the first position corresponding to the position of an initial anchor point (7) of an initial terminal segment (5A) and the second position corresponding to the position of a landing threshold point (LTP) of said runway (3); - to check whether the initial terminal segment (5A) of the virtual path (TV) crosses the threshold (12) of the runway (3); and - if said distance (D1, D2) between the first position and the second position is less than said predetermined distance (dAP) and if the initial terminal segment (5A) of the virtual path (TV) crosses the threshold (12) of the runway (3), to define said landing threshold point (LTP) as an anchor point (AP).

8. A set of avionics systems for implementing a non-precision FLS approach mode of an aircraft, with a view to landing the aircraft (AC) on a runway (3) of an aerodrome (4), said set (2) comprising at least one flight management system configured to use a final virtual path (TV) a terminal segment (5) of which is defined with respect to an anchor point (AP), characterized in that it comprises at least one avionics computer (1) for adapting an anchor point (AP) as claimed in claim 7 and in that it is configured to use the anchor point (AP) defined by said avionics computer (1) as an anchor point of the terminal segment (5) of the virtual path (TV).

9. The set as claimed in claim 8, characterized in that it additionally comprises at least one of the following systems: a flight warning system (10), a flight guidance system (11), a terrain avoidance and warning system (13), and in that it is configured to implement at least one of the following actions during the landing of the aircraft (AC): - guiding the aircraft (AC) at least along the terminal segment (5) of the virtual path (TV), as far as a touchdown zone (18) on the runway (3); - monitoring the aircraft (AC) as far as a touchdown zone (18) on the runway (3), so as to detect, where applicable, a deviation (PDEz) of the current position (PC) of the aircraft (AC) with respect to the terminal segment (5) of the virtual path (TV); - in the event of detection of a deviation (PDEz) greater than a predetermined value, emitting at least one of the following warnings in the cockpit of the aircraft (AC): a visual warning, an acoustic warning.

10. An aircraft, characterized in that it comprises at least one set (2) of avionics systems (1, 10, 11, 13, 15, 16, 17, 21) as claimed in either of claims 8 and 9.

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