(19)
(11)EP 2 703 926 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
16.02.2022 Bulletin 2022/07

(21)Application number: 13181748.8

(22)Date of filing:  26.08.2013
(51)International Patent Classification (IPC): 
G05D 1/02(2020.01)
G08G 5/00(2006.01)
(52)Cooperative Patent Classification (CPC):
G05D 1/0202; G08G 5/003

(54)

Aircraft control system and method for reaching a waypoint at a required time of arrival

Flugzeugsteuersystem und Verfahren zum Erreichen eines Wegpunktes zu einer erforderlichen Ankunftszeit

Système et procédé de commande d'aéronef permettant d'atteindre un point de cheminement à une heure d'arrivée requise


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 31.08.2012 US 201213602076

(43)Date of publication of application:
05.03.2014 Bulletin 2014/10

(73)Proprietor: Honeywell International Inc.
Morris Plains, NJ 07950 (US)

(72)Inventors:
  • Polansky, Michal
    Morristown, NJ New Jersey 07962-2245 (US)
  • Jancik, Zdenek
    Morristown, NJ New Jersey 07962-2245 (US)
  • Jackson, Mike
    Morristown, NJ New Jersey 07962-2245 (US)
  • Paricaud, Erwan
    Morristown, NJ New Jersey 07962-2245 (US)

(74)Representative: LKGlobal UK Ltd. 
Cambridge House Henry Street
Bath BA1 1BT
Bath BA1 1BT (GB)


(56)References cited: : 
WO-A1-02/093281
US-A1- 2011 029 158
US-A1- 2010 114 407
US-A1- 2011 295 501
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    TECHNICAL FIELD



    [0001] The exemplary embodiments described herein generally relates to managing aircraft mission profiles and more particularly to adjusting aircraft mission profiles for reaching a waypoint at a required time of arrival. The present invention in its various aspects is as set out in the appended claims.

    BACKGROUND



    [0002] World wide air traffic is projected to double every ten to fourteen years and the International Civil Aviation Organization (ICAO) forecasts world air travel growth of five percent per annum until the year 2020. Such growth may have an influence on flight performance and may increase the workload of the flight crew. In order to handle the expected increase in air traffic, the Next Generation Air Transportation System (NextGen) will introduce major transformations in Air Traffic Management (ATM), for example, aircraft trajectory-based operations. Trajectory-based operations will manage National Airspace System (NAS) resources by requiring aircraft to precisely follow custom-made 4-D trajectories consisting of a specified path along-path time conformance requirements. This promotes prescribing and accurately following trajectories that ensure separation and optimize traffic flow management over different time horizons, which will significantly improve flight safety and performance.

    [0003] Patent document number US2010/114407A1 describes methods and a system for a vehicle control system using a reference time profile including an upper control bound and a lower control bound are provided. The system includes an input device configured to receive a required time of arrival at a waypoint and a processor communicatively coupled to said input device wherein the processor is programmed to generate a reference time profile using a first speed profile up to an intermediate control point and a second speed profile between the intermediate control point and an RTA waypoint. The system also includes an output device communicatively coupled to the processor wherein the output device is configured to transmit a speed control signal based on the reference time profile to a vehicle speed control system.

    [0004] Patent document number WO02/093281A1 describes a system and method for controlling the flight of an aircraft to meet an RTA. The system comprises a speed profile generator that communicates with a trajectory generator to produce a speed profile signal that enables the aircraft to reach waypoint substantially at a predetermined time. The speed profile generator receives a nominal speed command signal, a time error signal and a sensitivity signal. Based on these inputs, the speed profile generator produces a speed profile signal. The trajectory generator receives the speed profile signal and a required time of arrival signal. Based on these signals, the trajectory generator produces a time error signal and a sensitivity signal. This sensitivity signal represents the sensitivity of the time error signal to changes in the speed profile signal

    [0005] Patent document number US2011/295501A1 describes a method and device which establishes trajectory planning, predictions and guidance so as to obtain the satisfaction of a time constraint (RTA). This objective is achieved by undertaking a computation of a trajectory up to the point where the flypast time constraint applies, on the basis of a profile of altitude and speeds, and then by computing the profile of speeds and altitudes making it possible, throughout the computed trajectory, to comply with the RTA. The method is also a method for readapting the trajectory and the vertical profile when during a mission, the data outside the aeroplane have caused the time predictions to drift and the constraint is no longer complied with under the initial speeds and trajectory assumptions.

    [0006] Patent document number US2011/029158A1 describes a method and systems for controlling a speed of a vehicle. The control system includes an input device configured to receive a required time of arrival (RTA) at a waypoint and a processor communicatively coupled to said input device, said processor programmed to automatically determine a dynamically adjustable range for an autothrottle control using an RTA error and a speed control tolerance, the RTA error representing a difference between an estimated time of arrival (ETA) and the RTA, the speed control tolerance representing a tolerance range about the vehicle speed profile. The control system also includes an output device communicatively coupled to said processor, said output device is configured to transmit at least one of a thrust control signal and a drag control signal to a speed control system of the vehicle.

    [0007] However, there are three major issues associated with the 4D operational concept encountered during steady wind error environment. First, deconfliction of the airspace and prevention of a separation infringement requires a reliable 4D trajectory. It uses Required Time of Arrival (RTA) to guarantee the reliability of time of arrival at a merging waypoint (RTA waypoint). However, the reliability before the waypoint is not guaranteed. An aircraft not compliant with its 4D trajectory may allow the spacing between aircraft to become too small.

    [0008] Second, the reliability of the RTA waypoint is limited if the aircraft cannot accelerate/decelerate to compensate for wind and temperature errors. To prevent this situation, aircraft typically use a "reliable RTA window" that is computed as the time at the RTA waypoint in case of maximum speeds and 95% headwind error for a first boundary and minimum speed and 95% tailwind for a second boundary. If for example, the minimum RTA is required, there is still a speed margin of the 95% headwind error that can be used for acceleration. However, if the 95% headwind really occurs, the predictions will expect the wind error to disappear and the aircraft would accelerate less than necessary to compensate for the error. This is desirable to prevent high engine activity, but if the wind error does not disappear, the aircraft will accumulate a position/time error and may saturate the guidance speed far before the RTA waypoint, resulting in the RTA being missed. The issue is symmetrical: the same will happen for the maximum RTA and steady tailwind error. To guarantee reliable RTA at a waypoint 200NM from the aircraft in case of 95% steady wind error, the margin applied on the speed envelope would need to be about twice the 95% wind error. This is the main weakness of the RTA concept: a limited RTA reliable window size (an aircraft speed envelope at FL350 can be between 20-50kts based on current gross weight). For a typical 95% wind error of about 8kts (8kts true air speed (TAS) equivalent to 5kts calibrated air speed (CAS) at high altitude), using 10kts (two times 5kts) from each side of the speed envelope would drastically reduce the reliable window.

    [0009] Third, in the case of RTA in descent and steady wind error, the system has to update descent speeds several times, resulting in the previously constructed descent path no longer being optimal. The pilot may have to use airbrakes/thrust to follow or recapture the descent path, resulting in less fuel efficiency, additional pilot workload, reduce passenger comfort, and aircraft structure load constraint that can reduce the residual life of the aircraft structure. From an airline perspective, this functionality may influence the cost of RTA operations. With an improvement in the RTA reliability and the reliable RTA window, an RTA selection close to airline cost & fuel policy may be made.

    BRIEF SUMMARY



    [0010] The present invention in its various aspects is as set out in the appended claims.

    [0011] A system and method are provided for an aircraft to arrive at a waypoint at a required time of arrival.

    [0012] A first exemplary embodiment includes a method for providing reliability for both an aircraft four dimensional trajectory along a path to a waypoint and a required time of arrival at the waypoint, comprising enabling a temporary speed correction that compensates for wind and temperature error in addition to a long term speed profile.

    [0013] A second claimed embodiment includes a method for providing reliability for both an aircraft four dimensional trajectory along a path to a waypoint and required time of arrival at the waypoint, comprising computing a first estimated speed to reach the waypoint at the required time of arrival; computing a time difference between an estimated time of arrival at the first estimated speed and the required time of arrival; setting and maintaining a target speed equal to the first estimated speed required to reach the waypoint at the required time of arrival plus a guidance margin if the time difference between the estimated time of arrival and the required time of arrival exceeds a first time threshold, the first time threshold defined by an estimated time of arrival tolerance and the estimated time to the waypoint, the first time threshold decreasing in magnitude as the distance to the waypoint decreases and as long as it is larger than a third time threshold, wherein the third time threshold is below the first time threshold, wherein the guidance margin is a speed delta applied to the first estimated speed; updating the target speed to equal a second estimated speed required to reach the waypoint at the required time of arrival plus the guidance margin if the difference between the estimated time of arrival and the required time of arrival exceeds a second time threshold and maintaining the guidance margin to compensate for accumulated time and position error in comparison to an initial predicted trajectory; and setting the guidance margin to zero and setting the guidance target speed to equal a latest estimated speed required to reach the waypoint at the required time of arrival if the time difference goes below the third time threshold. Further, this method also comprises compensating for wind and temperature error in addition to a long term speed profile, as disclosed in the first example embodiment.

    [0014] A third claimed embodiment includes a system, for carrying out the method of the claimed second embodiment, by providing reliability for both an aircraft four dimensional trajectory along a path to a waypoint and a required time of arrival at the waypoint, the system comprising a required time of arrival solver configured to calculate a first estimated speed to reach the waypoint at the required time of arrival; a trajectory predictor configured to compute in real time a time difference between an estimated time of arrival at the first estimated speed and the required time of arrival; a speed profile generator configured to set and maintain a target speed equal to the first estimated speed required to reach the waypoint at the required time of arrival plus a guidance margin if the time difference between the estimated time of arrival and the required time of arrival exceeds a first time threshold, the first time threshold defined by an estimated time of arrival tolerance and the time to the waypoint and which decreases in magnitude as the distance to the waypoint decreases and as long as it is larger than a third time threshold, wherein the guidance margin is a speed delta applied to the first estimated speed; wherein the required time of arrival solver is further configured to compute a second estimated speed required to reach the waypoint at the required time of arrival if a time error exceeds a second time threshold; wherein the speed profile generator is further configured to update the target speed to equal the second estimated speed required to reach the waypoint at the required time of arrival plus the guidance margin if a time error exceeds a second time threshold and maintaining the guidance margin to compensate some accumulated time error, wherein the second time threshold is larger than the first time threshold; and wherein the speed profile generator is configured to set the guidance margin to zero and setting the guidance target speed to equal the second estimated speed required to reach the waypoint at the required time of arrival if the time difference goes below a third time threshold.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0015] 

    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and

    FIG. 1 is a functional block diagram of a known required time of arrival system;

    FIG. 2 is a graph of error from a predicted trajectory versus time from a waypoint in accordance with an exemplary embodiment;

    FIG. 3 is a flow chart of a method for reaching the waypoint at the required time of arrival in accordance with the exemplary embodiment;

    FIG. 4 is a flow chart of a method for determining the speed required of the aircraft in accordance with the exemplary embodiment;

    FIG. 5 is a graph comparing time verses time error, the original speed target, and the guidance margin for an equivalent guidance margin and steady state wind error;

    FIG. 6 is a graph comparing time verses time error, the original speed target, and the guidance margin for a lower steady state wind error; and

    FIG. 7 is a graph comparing time verses time error, the original speed target, and the guidance margin for a higher steady state wind error.


    DETAILED DESCRIPTION



    [0016] The following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description.

    [0017] A method and system for improving four dimension (4D) trajectory reliability and required time of arrival (RTA) reliability in accordance with an exemplary embodiment comprises modifying the long term speed profile, and triggering and disengaging the modification in a way that is not reflected in the flight plan predictions.

    [0018] A guidance margin (GM) is triggered once the GM threshold is exceeded without re-computation of the speed profile. The GM is applied in Guidance only. This results in the possibility of slightly exceeding any speed constraint or limit. The GM is applied independently on the speed re-computation. This new approach leads to smaller speed adjustments, which desirably reduces, for example, engine variation, guidance mode switching, airbrakes requests, and thereby increases flight smoothness.

    [0019] The exemplary embodiments use two different strategies when performing 4D operation in an environment with weather uncertainties. First, a long term strategy of changing the speeds along the trajectory to remove the time error in predictions, while smooth and economic, fails by itself in case of steady forecast error. Second, by combining a short term strategy with the long term strategy compensates for that weakness.

    [0020] Various strategies could be applied that are based on short term action compensating the current wind error and position error. One strategy would be to temporarily change the aircraft guidance speed target by applying a guidance margin (constant or adjustable) that would either delay or prevent re-computation of the speed targets along the whole trajectory. The predictions would use the original speed target without the guidance margin application. The guidance speed target will stay applied until the predicted time error crosses a threshold.

    [0021] An adjustable guidance margin could be an adjustable value computed with respect to, for example, weather error (wind error plus temperature error), distance to the RTA waypoint, and speed. This would also smooth speed changes in a calm environment (low wind uncertainties). To guarantee the reliability in case of 95% wind error, it needs the guidance margin equivalent to that value: about 5 kts CAS (8 kts TAS) in high altitudes to compensate for the typical 95% weather error (8-12kts).

    [0022] This mechanism will stop or reduce the accumulation of the time delay and position error. If the guidance margin is not sufficient, the time error at the RTA waypoint would exceed some threshold, resulting in the speed target being recomputed in accordance with the long term strategy. The new aircraft guidance target would be a mix of long term strategy speed and guidance margin applied to recover some position/time error.

    [0023] With the exemplary embodiments, the re-computation of the speeds along the trajectory would be less frequent or not necessary, reducing the risk of speed saturation before the RTA waypoint, reducing the need for speed break, and keeping the 4D trajectory close to its original definition. If only small changes in speed occur during a vertical trajectory, for example, during climbs and descents, the descent vertical trajectory would remain close to the optimal one. The exemplary embodiments minimize the variation of the vertical trajectory by reducing occurrences of vertical path recapture maneuvers. These maneuvers often require use of airbrakes that are not efficient from a fuel, noise or comfort perspective. A benefit of the exemplary embodiments is the higher reliability of the 4D trajectory and the RTA reliability in all flight phases, which is the key enabler of the future air traffic management concept developed under SESAR and NEXTGEN projects.

    [0024] Techniques and technologies may be described herein in terms of functional and/or logical block components, and with reference to symbolic representations of operations, processing tasks, and functions that may be performed by various computing components or devices. Such operations, tasks, and functions are sometimes referred to as being computer-executed, computerized, software-implemented, or computer-implemented. In practice, one or more processor devices can carry out the described operations, tasks, and functions by manipulating electrical signals representing data bits at memory locations in the system memory, as well as other processing of signals. The memory locations where data bits are maintained are physical locations that have particular electrical, magnetic, optical, or organic properties corresponding to the data bits. It should be appreciated that the various block components shown in the figures may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions. For example, an embodiment of a system or a component may employ various integrated circuit components, e.g., memory elements, digital signal processing elements, logic elements, look-up tables, or the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices.

    [0025] For the sake of brevity, conventional techniques related to graphics and image processing, navigation, flight planning, aircraft controls, aircraft data communication systems, and other functional aspects of certain systems and subsystems (and the individual operating components thereof) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the subject matter.

    [0026] The known long term strategy mentioned above is accomplished by an algorithm in accordance with the exemplary embodiment of diagram 100 of FIG. 1. A trajectory predictor 102 computes the ETA A RTA solver 104 determines the speed adjustment in response to a signal 105 providing the RTA. A speed adjustment parameter, determined from the ETA and ETA partial derivatives, and the speed adjustment, is applied by the speed profile generator 106. The algorithm converges quickly in several passes around the diagram 100, depending upon the magnitude of the time error at the initial speed profile 103.

    [0027] In order to reject disturbances encountered during flight, the algorithm is executed repeatedly during the flight based on the latest navigational sensor data. Since each iteration of the algorithm requires a full pass of the trajectory predictions to perform, it will execute periodically, for example every 1 to 10 seconds, depending upon the speed of the FMS processor. During this interval, the speed profile generated from the most recent iteration is sent to the vertical guidance system.

    [0028] To ensure that the ground-based conflict probe retains accuracy with the aircraft autonomously changing the speed profile, the 4D trajectory can be periodically down-linked to the Air Traffic Management system automatically. By placing the RTA constraint, or constraints, at appropriate choke points or aircraft trajectory crossing points, the autonomous speed modifications by the aircraft will ensure that the trajectory remains conflict-free with a minimum of controller workload. The resulting aircraft trajectory retains the desired FMS speed profile shape familiar to pilots, while allowing errors due to wind uncertainty in portions of the trajectory that are not critical to the traffic situation in order to reduce throttle activity, fuel consumption, and engine wear.

    [0029] FIG. 2 is a graph of ETA error (the difference between when the aircraft is expected to reach the waypoint (based on actual flight data) and the required arrival time) versus time to reach the waypoint. A first threshold 202 (outer funnel) illustrates the long term strategy of changing the speeds along the trajectory to remove the time error in predictions. A second threshold 204 (inner funnel) illustrates the short term strategy for compensating the current wind error and position error. Preferably, the ETA error versus time to the waypoint for an aircraft will remain within the second funnel 204. However, should the predicted time error at the waypoint (required time of arrival point) intersect the second funnel 204 (short term strategy using GM), the aircraft speed would be changed to compensate for the wind error.

    [0030] FIGS. 3 and 4 are flow charts that illustrate an exemplary embodiment of processes 300, 400 suitable for use with a system for improving four dimension (4D) trajectory reliability and required time of arrival (RTA) reliability. The various tasks performed in connection with processes 300, 400 may be performed by software, hardware, firmware, or any combination thereof. For illustrative purposes, the following description of processes 300, 400 may refer to elements mentioned above in connection with FIGS. 1 and 2. In practice, portions of processes 300, 400 may be performed by different elements of the described system, e.g., a processor, a display element, or a data communication component. It should be appreciated that processes 300, 400 may include any number of additional or alternative tasks, the tasks shown in FIGS. 3 and 4 need not be performed in the illustrated order, and processes 300, 400 may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein. Moreover, one or more of the tasks shown in FIGS. 3 and 4 could be omitted from an embodiment of the processes 300, 400 as long as the intended overall functionality remains intact.

    [0031] Referring to FIG. 3, the guidance target at the current RTA speed and current guidance margin is computed 302 and the time error at the RTA waypoint without usage of the guidance margin is computed 304. If the time error exceeds 306 the first threshold 202, the RTA speeds are recomputed to compensate for the time error while keeping the guidance margin active. If the time error does not exceed 306 the first funnel 202, and the time error exceeds 310 the second funnel 204, the guidance margin is computed and applied 312. If the time error does not exceed 310 the second funnel 204, and the time error has been reduced sufficiently to remove the guidance margin 314, the guidance margin is set to zero 316. If the time error has not been reduced sufficiently to remove the guidance margin 314, the guidance margin is not changed 318. Subsequent to steps 308, 312, 316, and 318, step 302 is repeated.

    [0032] FIG. 4 illustrates the guidance module process 400, including obtaining 402 the guidance margin and the original guidance target from the above process, applying 404 the guidance margin on the original guidance target, and providing 406 the speed target to the autopilot.

    [0033] The graph of FIG. 5 illustrates for the combined short term strategy and the long term strategy for an equivalent guidance margin and at a given speed 502, for example 400 kts, when the time error for the time to ETA 504 reaches the second funnel 204 (threshold), the guidance margin 506 in true airspeed is increased, and added to the original speed target to be sent to the autopilot. If the time error continues to increase, and exceed the outer funnel 206 at point 508, then the long term strategy will apply an additional speed target increase 510, combined with the guidance margin 506.

    [0034] The graph of FIG. 6 illustrates for the combined short term strategy and the long term strategy for a lower steady state wind error and at a given speed 602, for example 400 kts, when the time error for the time to ETA 604 reaches the second funnel 204 is reached, the guidance margin 606 is increased, and when the time error and time to ETA reaches zero, the guidance margin 606 is decreased.

    [0035] The graph of FIG. 7 illustrates for the combined short term strategy and the long term strategy for a higher steady state wind error, when the time error 704 for the ETA increases to the second funnel, the guidance margin 706 is increased. As the time error 704 continues to increase and eventually reaches the first funnel 202, the speed is increased at point 708 to the speed 710, wherein the time error 704 drops to the first funnel at point 708. If the time error 704 continues to increase and again reaches the first funnel 202, the speed is increased at point 712 to the speed 714. This increase in time error 704 and airspeed continues until the waypoint is reached.

    [0036] The implementation can be done in any RTA capable FMS, but also within an Autopilot or other system using information of time error, and 4D trajectory variation monitoring that would be provided by a RTA capable FMS.

    [0037] There are multiple ways to determine when to apply the guidance margin speed and when to stop its application. The mechanism can be used either always during the 4D operations or only when the aircraft speed gets close to the speed envelope. There might be considered various other conditions. The triggering can use the position error or the time error estimation. In case of time error based threshold, the guidance margin could be applied when the long term strategy leads to a speed adjustment along the whole trajectory.

    [0038] The threshold is typically 5 to 9 seconds in case of a 10 seconds RTA tolerance with the RTA waypoint within the next 200 NM. The full speed adjustment would be triggered, once the time error exceeds the RTA tolerance. However the long term speed update would not compensate the whole 10 seconds, but just the 5 to 9 seconds (with the objective to remain active to converge with the GM for resetting to zero). The speed update would be the same as in the current long term strategy. The guidance margin would be maintained, the pilot would see the speed increase to compensate for the headwind error, and the total time error reducing slowly.

    [0039] In case the wind error is less than the change in speed, the time error would decrease. When the time error gets compensated due to being below a threshold, the delta speed would be removed and original speed target would be used.

    [0040] The value of the guidance margin could be either constant or computed based on the situation. To guarantee the RTA reliability even when the RTA is on the edge of the current RTA reliable window, it should be at least equal to the 95% wind error, but it would increase the reliability and performance even if the value is much lower. So it can be simply set to some constant value, e.g. 0.01 Mach or 5 kts CAS. It was confirmed by a human factors study in the European ERASMUS project that ATC is not disturbed by up to five percent of current speed, for example, 10kts CAS difference.

    [0041] From a human machine interface (HMI) perspective, it could be advantageous to display upper speed margin and lower speed margin on Primary Flight Display, on Airbus aircraft for example, allowing the FMS to vary guidance speed target without creating pilot misunderstanding. That system using a similar concept would have to avoid the impact of the short term strategy on the immediate time error predictions which are used for the long term strategy.

    [0042] In accordance with another exemplary embodiment, a method for providing reliability for both an aircraft four dimensional trajectory along a path to a waypoint and required time of arrival at the waypoint comprises enabling a temporary speed correction that compensates for current wind error in addition to a long term speed profile.


    Claims

    1. A method (400) for providing reliability for both an aircraft four dimensional trajectory along a path to a waypoint and a required time of arrival at the waypoint, comprising:

    computing a first estimated speed to reach the waypoint at the required time of arrival (RTA);

    computing a time difference between an estimated time of arrival at the first estimated speed and the required time of arrival;

    setting and maintaining a target speed equal to the first estimated speed required to reach the waypoint at the required time of arrival plus a guidance margin and which is termed a guidance target speed;

    enabling a temporary speed correction, using the guidance margin, wherein the enabling step comprises:

    a) computing a time difference between an estimated time of arrival (ETA) (604) and a required time of arrival without use of a guidance margin (304), wherein the guidance margin (314) is a speed change applied to the first estimated speed (312); for updating the guidance target speed to equal a second estimated speed required to reach the waypoint at the required time of arrival;

    setting the guidance target speed required to reach the waypoint at the RTA plus the guidance margin (302)

    if the time difference between an ETA (604) and an RTA does not exceed a first time threshold, being a first, outer, funnel (202), which decreases in magnitude as the distance to the waypoint decreases, and

    if the time difference does not exceed (310) a second time threshold being a second, inner, funnel (204), which decreases in magnitude as the distance to the waypoint decreases;

    setting the guidance target speed to equal a speed required to reach the waypoint at the RTA plus an updated guidance margin (312)
    if the time error exceeds (306) the first time threshold, being said a first, outer, funnel (202);

    re-computing (310) the guidance margin and the guidance target speed to reach the waypoint at the RTA, and setting the guidance target speed to equal the speed required to reach the waypoint at the RTA plus the re-computed guidance margin if the time error exceeds the second time threshold, being the second, inner, funnel (204);

    setting the guidance margin to zero (316) and setting the guidance target speed to equal the speed required to reach the waypoint at the RTA plus the guidance margin if the time difference goes below a third time threshold; and
    b) repeating from a), wherein the guidance margin compensates for wind and temperature error in addition to a long term speed profile wherein the setting of the target speed includes setting the guidance margin in consideration of a change in wind and temperature from that used to set the target speed so as to provide a guidance target speed.


     
    2. The method of claim 1 wherein the first and second time thresholds (202, 204) are displayed as funnels.
     
    3. A system for providing reliability for both an aircraft four dimensional trajectory along a path to a waypoint and a required time of arrival at the waypoint, the system comprising:
    various computing components or devices configured to perform the method of claim 1.
     
    4. The system of claim 3 further comprising a display configured to display the first and second time thresholds (202, 204) as funnels.
     


    Ansprüche

    1. Verfahren (400) zum Bereitstellen von Zuverlässigkeit sowohl für eine vierdimensionale Flugbahn eines Flugzeugs entlang eines Wegs zu einem Wegpunkt als auch für eine erforderliche Ankunftszeit am Wegpunkt, umfassend:

    Berechnen einer ersten geschätzten Geschwindigkeit, um den Wegpunkt mit der erforderlichen Ankunftszeit (RTA) zu erreichen;

    Berechnen einer Zeitdifferenz zwischen einer geschätzten Ankunftszeit mit der ersten geschätzten Geschwindigkeit und der erforderlichen Ankunftszeit;

    Einstellen und Aufrechterhalten einer Zielgeschwindigkeit, die gleich der ersten geschätzten Geschwindigkeit ist, die erforderlich ist, um den Wegpunkt mit der erforderlichen Ankunftszeit plus einer Führungsmarge zu erreichen, und die als Führungszielgeschwindigkeit bezeichnet wird;

    Aktivieren einer temporären Geschwindigkeitskorrektur unter Verwendung der Führungsmarge, wobei der Aktivierungsschritt umfasst:

    a) Berechnen einer Zeitdifferenz zwischen einer geschätzten Ankunftszeit (ETA) (604) und einer erforderlichen Ankunftszeit ohne Verwendung einer Führungsmarge (304), wobei die Führungsmarge (314) eine Geschwindigkeitsänderung ist, die auf die erste geschätzte Geschwindigkeit (312) angewendet wird; zum Aktualisieren der Führungszielgeschwindigkeit, um gleich einer zweiten geschätzten Geschwindigkeit zu sein, die erforderlich ist, um den Wegpunkt mit der erforderlichen Ankunftszeit zu erreichen;

    Einstellen der Zielgeschwindigkeit, die erforderlich ist, um den Wegpunkt mit der RTA plus der Führungsmarge (302) zu erreichen,

    wenn die Zeitdifferenz zwischen einer ETA (604) und einer RTA einen ersten Zeitschwellenwert nicht überschreitet, der ein erster äußerer Trichter (202) ist, dessen Größe mit abnehmender Entfernung zum Wegpunkt abnimmt, und

    wenn die Zeitdifferenz (310) nicht überschritten wird, ein zweiter Zeitschwellenwert ein zweiter, innerer Trichter (204) ist, dessen Größe mit abnehmender Entfernung zum Wegpunkt abnimmt;

    Einstellen der Zielführungsgeschwindigkeit auf eine Geschwindigkeit, die erforderlich ist, um den Wegpunkt mit der RTA plus einer aktualisierten Führungsmarge (312) zu erreichen,
    wenn der Zeitfehler (306) den ersten Zeitschwellenwert überschreitet, er ein genannter erster äußerer Trichter (202) ist;

    Neuberechnen (310) der Führungsmarge und der Zielführungsgeschwindigkeit, um den Wegpunkt mit der RTA zu erreichen, und Einstellen der Zielführungszielgeschwindigkeit gleich der Geschwindigkeit, die erforderlich ist, um den Wegpunkt mit der RTA plus der neu berechneten Zielführungsmarge zu erreichen, wenn der Zeitfehler den zweiten Zeitschwellenwert überschreitet, der der zweite innere Trichter (204) ist;

    Einstellen der Führungsmarge auf Null (316) und Einstellen der Führungszielgeschwindigkeit gleich der Geschwindigkeit, die erforderlich ist, um den Wegpunkt mit der RTA plus der Führungsmarge zu erreichen, wenn die Zeitdifferenz unter einen dritten Zeitschwellenwert sinkt; und
    b) Wiederholen von a), wobei die Führungsmarge Wind- und Temperaturfehler zusätzlich zu einem langfristigen Geschwindigkeitsprofil kompensiert, wobei das Einstellen der Zielgeschwindigkeit das Einstellen der Führungsmarge unter Berücksichtigung einer Änderung des Windes und der Temperatur gegenüber der zum Einstellen der Zielgeschwindigkeit verwendeten umfasst, um eine Führungszielgeschwindigkeit bereitzustellen.


     
    2. Verfahren nach Anspruch 1, wobei der erste und zweite Zeitschwellenwert (202, 204) als Trichter angezeigt werden.
     
    3. System zum Bereitstellen von Zuverlässigkeit sowohl für eine vierdimensionale Flugbahn eines Flugzeugs entlang eines Wegs zu einem Wegpunkt als auch für eine erforderliche Ankunftszeit am Wegpunkt, wobei das System umfasst:
    verschiedene Computerkomponenten oder-vorrichtungen, die konfiguriert sind, um das Verfahren nach Anspruch 1 durchzuführen.
     
    4. System nach Anspruch 3, das ferner eine Anzeige umfasst, die konfiguriert ist, um den ersten und zweiten Zeitschwellenwert (202, 204) als Trichter anzuzeigen.
     


    Revendications

    1. Procédé (400) permettant d'assurer la fiabilité à la fois d'une trajectoire quadridimensionnelle d'un aéronef le long d'un trajet jusqu'à un point de cheminement et d'une heure d'arrivée requise au point de cheminement, comprenant :

    le calcul d'une première vitesse estimée pour atteindre le point de cheminement à l'heure d'arrivée requise (RTA) ;

    le calcul d'une différence de temps entre une heure d'arrivée estimée à la première vitesse estimée et l'heure d'arrivée requise ;

    le réglage et le maintien d'une vitesse cible égale à la première vitesse estimée, requise pour atteindre le point de cheminement à l'heure d'arrivée requise, plus une marge de guidage, et qui est appelée vitesse cible de guidage ;

    l'activation d'une correction de vitesse temporaire, en utilisant la marge de guidage, dans lequel l'étape d'activation comprend :

    a) le calcul d'une différence de temps entre une heure d'arrivée estimée (ETA) (604) et une heure d'arrivée requise sans utilisation d'une marge de guidage (304), dans lequel la marge de guidage (314) est un changement de vitesse appliqué à la première vitesse estimée (312) ; pour mettre à jour la vitesse cible de guidage afin qu'elle soit égale à une seconde vitesse estimée, requise pour atteindre le point de cheminement à l'heure d'arrivée requise ;

    le réglage de la vitesse cible de guidage requise pour atteindre le point de cheminement à la RTA, plus la marge de guidage (302)

    si la différence de temps entre une ETA (604) et une RTA ne dépasse pas un premier seuil de temps, qui est un premier entonnoir externe (202), dont l'amplitude diminue à mesure que la distance jusqu'au point de cheminement diminue, et

    si la différence de temps ne dépasse pas (310) un deuxième seuil de temps qui est un second entonnoir interne (204), dont l'amplitude diminue à mesure que la distance jusqu'au point de cheminement diminue ;

    le réglage de la vitesse cible de guidage pour qu'elle soit égale à une vitesse requise pour atteindre le point de cheminement à la RTA, plus une marge de guidage mise à jour (312)
    si l'erreur de temps dépasse (306) le premier seuil de temps, qui est ledit premier entonnoir externe (202) ;

    le recalcul (310) de la marge de guidage et de la vitesse cible de guidage pour atteindre le point de cheminement à la RTA et le réglage de la vitesse cible de guidage pour qu'elle soit égale à la vitesse requise pour atteindre le point de cheminement à la RTA, plus la marge de guidage recalculée si l'erreur de temps dépasse le deuxième seuil de temps, qui est le second entonnoir interne (204) ;

    le réglage de la marge de guidage sur zéro (316) et le réglage de la vitesse cible de guidage pour qu'elle soit égale à la vitesse requise pour atteindre le point de cheminement à la RTA, plus la marge de guidage, si la différence de temps passe en dessous d'un troisième seuil de temps ; et
    b) la répétition à partir de a), dans lequel la marge de guidage compense l'erreur de vent et de température en plus d'un profil de vitesse à long terme, dans lequel le réglage de la vitesse cible comprend le réglage de la marge de guidage en tenant compte d'un changement de vent et de température par rapport à celui utilisé pour régler la vitesse cible de manière à fournir une vitesse cible de guidage.


     
    2. Procédé selon la revendication 1, dans lequel les premier et deuxième seuils de temps (202, 204) sont affichés sous forme d'entonnoirs.
     
    3. Système permettant d'assurer la fiabilité à la fois d'une trajectoire quadridimensionnelle d'un aéronef le long d'un trajet vers un point de cheminement et d'une heure d'arrivée requise au point de cheminement, le système comprenant :
    divers composants ou dispositifs de calcul configurés pour exécuter le procédé selon la revendication 1.
     
    4. Système selon la revendication 3, comprenant en outre un affichage configuré pour afficher les premier et deuxième seuils de temps (202, 204) sous forme d'entonnoirs.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description