GB2589302A

GB2589302A - Flight path modification system and method

Info

Publication number: GB2589302A
Application number: GB1915180.2A
Authority: GB
Inventors: Garai Tanushree; Virdhe Srushti
Original assignee: Airbus SAS
Current assignee: Airbus SAS
Priority date: 2019-10-21
Filing date: 2019-10-21
Publication date: 2021-06-02
Also published as: GB201915180D0

Abstract

A system for determining a flight path modification to an initial flight path of an aircraft includes a data receiver 102. Input data includes a start point and an end point representing spatial positions on the initial flight path; and time requirement data representing a time at which the aircraft is required to arrive at the end point. A processor 106 is arranged to analyse the received input data and to determine the flight path modification by calculating: based on the input data, a lateral profile modification to the initial flight path, and based on the lateral profile modification, a vertical profile modification to the initial flight path, and a data output arranged to output data representing the flight path modification. The input data may include aircraft speed, speed profile, or speed requirement. The path may be modified by increasing the distance to the end point by a predetermined amount, and recalculating the lateral and vertical flight path profile accordingly.

Description

FLIGHT PATH MODIFICATION SYSTEM AND METHOD

TECHNICAL FIELD

[0001] The present invention relates to a system and method for determining a modification to a flight path of an aircraft.

BACKGROUND

[0002] Separation management of aircrafts, such as on standard flight routes, known as Standard Terminal Arrival Routes (STAR) in descent and approach areas, is typically managed by manually sequencing the aircrafts with respect to a common merge point. Aircraft spacing requirements become more complex to manage in aircraft approach areas, where multiple aircraft routes converge into a common point in space known as a merge point; according to time separation requirements, a predetermined period of time must elapse between a leading aircraft reaching the merge point and a following aircraft reaching the merge point. To maintain the desired separation of approaching aircraft in terms of time or distance, the following aircraft is usually put on hold or diverted on an alternative route, as suggested by Air Traffic Control (ATC) in agreement with the pilot in command of the following aircraft. Currently, to handle a dynamic situation, such as a delay enforced by aircraft separation management protocols, a "HOLD-or deviation from the standard route is manually executed by the pilot of the following aircraft, with input from ATC controllers. Once in HOLD, the pilot is required to communicate with ATC constantly, as the decision-making process to exit HOLD depends on many factors, including the presence of traffic in the same airspace that has the same merge point. Thus, in such a situation, the workload of the pilot and of the ATC controller(s) is greatly increased.

[0003] When such a manual deviation from a standard route occurs, the pilot manually inputs a new flight path. In doing so, the pilot is required to assess the current state of the aircraft, such as the level of fuel on board, together with the implication of the new path with respect to traffic in the surrounding airspace. The resulting flight path typically deviates from the preferred path profiles that are used when planning an initial flight path along a standard route For example, an initial flight path may have a vertical profile that follows a "Continuous Descent/Approach" profile, which ensures that the angle of descent of the aircraft remains substantially constant. Deviating from such predetermined profiles leads to increases in fuel consumption and operational costs, and delays in destination arrival times.

SUMMARY

100041 A first aspect of the present invention provides a system for determining a flight path modification to an initial flight path of an aircraft, the system comprising: a data receiver arranged to receive input data, the input data including a start point and an end point representing spatial positions on the initial flight path, and time requirement data representing a time at which the aircraft is required to arrive at the end point; a processor arranged to analyse the received input data and to determine the flight path modification by calculating: i) based on the input data, a lateral profile modification to the initial flight path, and ii) based on the lateral profile modification, a vertical profile modification to the initial flight path; and a data output arranged to output data representing the flight path modification.

100051 Optionally, the input data comprises speed data including at least one of: a current speed of the aircraft; an aircraft speed profile based on the initial flight path; and a speed requirement relating to at least a portion of the initial flight path, and the processor is arranged to calculate a speed profile of the flight path modification based on the speed data.

100061 Optionally, the processor is arranged to: calculate the lateral profile modification by calculating a modified distance for the aircraft to travel from the start point to the end point; and based on the modified distance, calculate the vertical profile modification by calculating a modified angle of descent of the aircraft.

100071 Optionally, the processor is arranged to determine, based on the modified distance, an additional waypoint via which the aircraft is required to travel, such that the direct distance between the waypoint and the end point is substantially equal to the direct distance between the start point and the end point.

100081 Optionally, the input data comprises traffic data and the processor is arranged to: determine the existence of additional aircraft on the flight path modification; and determine an alternative flight path modification based on at least one of increasing the modified distance and changing a direction of travel to the additional waypoint.

100091 Optionally, the processor is arranged to determine an alternative flight path modification by: increasing the modified distance for the aircraft to travel to the end point by a predetermined amount; based on the increased distance, recalculating the lateral profile modification; based on the lateral profile modification, recalculating the vertical profile modification by recalculating the modified angle of descent of the aircraft; and based on the recalculated lateral and vertical profile modifications, calculating the alternative flight path modification.

100101 Optionally, the processor is arranged to iteratively determine alternative flight path modifications until a flight path modification absent of traffic is determined, or the processor determines that the increased distance exceeds the predetermined threshold distance 100111 Optionally, the system is arranged to apply the determined lateral and vertical path modifications to the aircraft.

100121 Optionally, the aircraft is a first aircraft, and the time requirement data is based on a required separation between the first aircraft and a second aircraft that is expected to arrive at the end point before the first aircraft.

100131 Optionally, the system is on-board the aircraft, 100141 Optionally, the system is ground-based.

100151 A second aspect of the present invention provides a computer-implemented method of determining a flight path modification to an initial flight path of an aircraft, the method comprising: receiving input data, the input data including: a start point and an end point representing spatial positions on the initial flight path; and time requirement data representing a time at which the aircraft is required to arrive at the end point; analysing the received data to determine the flight path modification by calculating: i) based on the input data, a lateral profile modification to the initial flight path, and ii) based on the lateral profile modification, a vertical profile modification to the initial flight path; and outputting data representing the flight path modification.

100161 Optionally, the method comprises calculating the lateral profile modification by calculating a modified distance for the aircraft to travel from the start point to the end point; and based on the modified distance, calculating the vertical profile modification by calculating a modified angle of descent of the aircraft.

100171 Optionally, the method comprises determining, based on the modified distance, a waypoint via which the aircraft is required to travel, such that the direct distance between the waypoint and the end point is substantially equal to the direct distance between the start point and the end point.

100181 Optionally, the method comprises: receiving speed data comprising at least one of a current speed of the aircraft, an aircraft speed profile based on the initial flight path, and a speed requirement relating to at least a portion of the initial flight path; and calculating a speed profile of the flight path modification based on the received speed data [0019] Optionally, the input data comprises traffic data and the method comprises: (i) determining the existence of additional aircraft on the flight path modification; (ii) increasing the modified distance for the aircraft to travel to the end point by said modified distance, (iii) comparing the increased distance to a predetermined threshold distance; (iv) based on the increased distance, recalculating the lateral profile modification; (v) based on the increased distance, recalculating the vertical profile modification by recalculating the modified angle of descent of the aircraft; (vi) based on the recalculated lateral and vertical profile modifications, recalculating the flight path modification; (vii) determining the existence of additional aircraft on the recalculated flight path modification; and (viii) repeating (ii)-(vii) until either a flight path modification absent of traffic is determined, or the processor determines that the increased distance exceeds the predetermined threshold distance.

100201 Optionally, the method comprises applying the determined lateral and vertical path modifications to the aircraft.

100211 A third aspect of the present invention provides a computer program, or a suite of computer programs, which, when executed by a processing system, causes the processing system to perform the above methods.

[0022] A fourth aspect of the present invention provides computer readable storage medium storing computer readable instructions thereon for execution on a computing system to implement the above methods.

[0023] A fifth aspect of the present invention provides a flight path modification system comprising: an input arranged to receive input data, the input data including a start point and an end point representing spatial positions on an initial flight path, and time requirement data representing a time at which the aircraft is required to arrive at the end point; a processor arranged to analyse the received data and to determine a modification to the initial flight path by calculating, based on the input data, a modification to the flight path in a lateral direction and a vertical direction; and a data output arranged to instruct an aircraft control system to apply the modified flight path to the aircraft such that the time requirement is met.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [0025] Figure 1 shows an example system 100 for determining a flight path modification according to the invention; [0026] Figures 2a-c show the geometry involved in calculating the flight path modification of Figure]; [0027] Figure 3 shows a flowchart of a method of determining a flight path modification according to the invention; and [0028] Figure 4 is an example of flight path modification options that are displayed to a pilot.

DETAILED DESCRIPTION

[0029] Figure 1 shows an example system 100 for determining a flight path modification to an initial or current flight path of an aircraft, based on a required time of separation between multiple aircraft. The system 100 automatically computes modifications to planned trajectories or profiles in the lateral and vertical planes based on a required time of arrival (RTA) of the aircraft at a particular point in space, referred to as a waypoint or merge point, in order to cater for aircraft separation requirements whilst maintaining an efficient flight path. Modification of the flight path by the system 100 is considered to be automatic, as manual calculation is eliminated, and dynamic, as the calculation is performed, and can be iteratively updated, during flight.

[0030] The system 100 may be an on-board Flight Management System (FMS). Alternatively, the system 100 may be, or form part of, another on-board system such as an Electronic Flight Bag (EFB) or an off-board, ground-based system. The system 100 has a communication interface, for example in the form of a data receiver 102 that is configured to receive input data from other on-board aircraft systems and external systems such as Air Traffic Control (ATC) 104. The data receiver 102 may be an input of a processor 106. The input data includes positional data and time requirement data. The time requirement data represents an RTA at which the aircraft is required to arrive at a particular point in space, such as a merge point on the initial planned route, to ensure that aircraft are safely spaced from one another.

[0031] Additional input data that may be used by the system 100 includes, for example: instructions from ATC; data relating to airspace policies, constraints and regulations; speed, time and altitude data, including current values, requirements and constraints; periodic updates of aircraft state parameters; periodic updates of metrological data (relating to the aircraft's own airspace, surrounding airports' airspace and en-route paths); periodic updates of air traffic (relating to the aircraft's own airspace, surrounding airports' airspace and en-route paths); additional pilot inputs; an initial flight plan, including associated lateral and vertical flight profiles; and data relating to techniques such as 4D trajectory management and Continuous Descent and Approach (CDA) profiles, including a dynamic speed profile and continuous descent profile used to plan the initial flight path. Such speed and descent profiles are used when planning a flight path in advance, in order to construct an efficient flight path and manage Required Time of Arrival (RTA) and fuel consumption. The data receiver 102 receives input data from off-board systems such as ATC 104, and from other "on-board" aircraft systems 108. The system 100 is operatively connected to a pilot interface 110 of the aircraft to allow the data receiver 102 to receive input data directly from the pilot.

[0032] The processor 106 is arranged to analyse the received data and to determine a flight path modification that ensures that the merge point is reached at the RTA and that the modified path is as close to the STAR as possible. The modified route can be referred to as a "dynamic direct path" (DIPATH) and involves both lateral and vertical profile computation. As will be described further with reference to Figure 2, based on the time requirement data a DIPATH start point and a DIPATH end point that are derived from the initial flight path, and additional data, such as aircraft speed data, the processor 106 calculates a lateral profile modification to the initial flight path. The lateral profile modification is a modified distance for the aircraft to travel to the DIPATH end point. Based on the lateral profile modification, the processor 106 then calculates a vertical profile modification to the initial flight path, by re-calculating the angle of descent of the aircraft. The angle of descent is re-calculated by taking into account the modified distance of the lateral profile modification such that the aircraft arrives at the end point at the RTA. The resulting flight path modification can be referred to as the DIPATH. By calculating modifications to both the lateral and vertical profiles, which are to be applied together, an alternative path that meets requirements efficiently, in terms of time, fuel and other resources, can be determined.

[0033] In calculating the modified distance for the aircraft to travel to the DIPATH end point, a speed of the aircraft is taken into consideration. This speed data may be received by the system 100 as input data. The speed data may be computed by a current speed profile computation algorithm of the system 100 or another on-board system, to be taken into account by the DIPATH algorithm. Speed data received by the system 100 may include data such as a current speed of the aircraft, a predetermined speed profile based on the current flight path, and a speed requirement relating to at least a portion of the current flight path. A current speed profile computation algorithm re-calculates the speed profile of the DIPATH route, ensuring that any speed requirements are met in an efficient way. For example, by taking into account a current speed that will be maintained when reaching the DIPATH start point, and a reduced velocity requirement that must be met at the DIPATH end point, the DIPATH algorithm calculates how to reduce the speed along the DIPATH route.

[0034] The system 100 has a data output 112 that is connected to or part of the processor 106. The data output 112 is configured to output data representing the DIPATH flight path modification, including the lateral and vertical profile modifications. The DIPATH flight path modification is output for application by an aircraft control system 114. The DIPATH can be output to a pilot display, in order to allow the pilot to assess and confirm that the DIPATH route should be followed. Additionally, data representing the DIPATH can be output to ATC, external on-board aircraft systems, external ground-based systems, or to aircraft within the surrounding airspace to aid collaborative airspace management. The output data representing the DIPATH can take the form of, or include, an instruction such that, either upon confirmation by the pilot or automatically, the DIPATH procedure can be undertaken by an autopilot system of the aircraft. In this way, the system 100 can be configured to apply the DIPATH flight path modification to the aircraft.

[0035] The calculation of the DIPATH is explained in more detail with reference to Figures 2a-c and Figure 3, Figures 2a-c show the geometry involved in calculating the lateral and vertical profiles of the DIPATH, while Figure 3 is a flowchart showing functions performed by the processor 106 in executing a DIPATH algorithm 300. In Figure 2a, a current, planned flight path (also referred to as an initial flight path) of a following aircraft, which may conform to a STAR flight path, follows a route from point Al, via point A2 to point A3 (Al-A2--A3) as shown. However, in order to manage a time separation requirement due to an expected future conflict with a separate "leading" aircraft, which is expected to reach the merge point A2 before the following aircraft, the following aircraft adjusts its RTA at A2 using the DIPATH procedure. As the following aircraft approaches Al along its initial flight path, it receives time requirement data, such as data indicative of an RTA that is based on an aircraft time separation requirement, at block 301, for example from an external system such as ATC. The DIPATH procedure can be enabled by the pilot on the system 100 at any time prior to, or upon, receiving the time separation data, for example via interaction with a Multi-Function Display (MFD) and Navigation Display (ND) of the aircraft, and once enabled the system 100 may automatically execute the DIPATH algorithm. The pilot may enable the DIPATH procedure from a particular downpath waypoint, for example from Al when aircraft approach paths begin to converge, via a display of the system 100. At block 302, data indicative of the start point Al and merge point or end point A2 from the initial flight path are automatically or manually entered into the system 100 for consideration by the DIPATH algorithm.

100361 At block 303 of Figure 3, the processor 106 determines a modified or additional distance Ad that the aircraft must travel, based on the current speed, default or predetermined speed or speed requirements, in order to meet the new RTA and hence the time separation requirement. As shown in Figure 2a, for the purposes of calculating a flight path modification between Al and A2, the lateral distance along the initial flight path from Al (the "start point") to A2 (the merge point or "end point") is considered to be the radius R of a hypothetical circle, with A2 representing the centre of the circle. As shown in Figure 2b, which mirrors the geometry of Figure 2a, the additional distance Ad, also referred to as a "distance-to-go", represents a distance around the circumference of the hypothetical circle that the following aircraft must travel before continuing along a radius R of the hypothetical circle to the merge point A2 100371 Referring to block 304, once the additional distance Ad has been calculated, a lateral profile modification is determined. In determining the lateral profile modification, a new waypoint Bl, referred to as the DIPATH waypoint, is calculated based on Ad. The processor 106 then constructs a new lateral profile from point Al, via the DIPATH way point Bl and merge point A2, to point A3 (Al BlA2A3) Based on the type of path construction and path transition through the DIPATH waypoint B1, lateral guidance commands are calculated by the system 100 100381 At block 305, the processor 106 determines the vertical profile modification based on the calculated lateral profile modification, by using the additional distance Ad to calculate a modified flight path angle AFPA. As shown in Figure 2c, the DIPATH increases the lateral distance travelled by the aircraft by a distance Ad, so in order to descend by an altitude Ah to the altitude of the merge point whilst maintaining a continuous descent, a flight path angle AFPA that is smaller than the initial flight path angle FPA is calculated. The processor 106 constructs the modified vertical profile, shown in Figure 2c as a dashed line, based on the modified flight path angle AFPA, and vertical guidance commands are determined by the system 100 accordingly. The processor 106 then validates the Expected Time of Arrival (ETA) of the aircraft at A2 with respect to the RTA based on the determined lateral and vertical modifications; using the RTA in a time-based flight path modification enables accurate prediction of the ETA at the merge point 100391 The DIPATH algorithm determines a modified flight path that is as close as possible to a standard STAR, so that divergence from the initial flight path is minimal and the risk of a major airspace violation within the deviation is minimised. Convergence onto the standard route is gradual, and hence efficient. The benefits of techniques such as 4D trajectory management and CDA techniques, for example a dynamic speed profile and a continuous descent flight profile to construct the DIPATH profile, ensure that an efficient path modification is followed, and the benefits of these techniques, which may have been used to construct the initial flight plan, are not lost when modifying the flight path. Additionally, the system 100 is configured to automatically construct a modified flight path, taking into account all relevant input data and critical constraints from onboard and off-board systems, thereby reducing pilot and ATC workload and providing a more robust technique than current manual and iterative methods of managing aircraft separation. Automation of the flight path modification by the DIPATH procedure also assists with, and improves reliability and safety in, Single Pilot Operation (SPO).

100401 It should be noted that although the time requirement data representing a time at which the aircraft is required to arrive at the end point can be based on a required aircraft time separation between aircraft, the DIPATH procedure can be invoked by circumstances other than required aircraft time separation, for example, a flight path modification such as a weather-related deviation or a traffic-related deviation may be determined using the DIPATH procedure.

100411 Additionally, and particularly in the case of congestion in approach airspace, the DIPATH algorithm can be performed iteratively to resolve a traffic conflict that arises as a result of calculating the lateral and vertical profile modifications of steps 304 and 305 of Figure 3. Referring to step 306, the system 100 assesses the presence of traffic on the calculated DIPATH route, for example using Automatic Dependent Surveillance ---Broadcast (ADS-Po technology and with the aid of real-time traffic data received by onboard systems or from ATC, and traffic conflicts are avoided by iteratively calculating new DIPATH routes. If no traffic collision is anticipated by the system 100, or any traffic is deemed to remain at a safe distance from the expected position of the following aircraft for the duration of the DIPATH route, the proposed DIPATH trajectory may be output to an on-board pilot display for review and confirmation by the pilot. This ensures that the pilot is presented with the possible diversions to the route, and upon confirmation by the pilot the DIPATH flight path modification is applied by the system, for example in the form of an instruction to an autopilot system to control the aircraft in accordance with the selected DIPATH flight path modification. The intended DIPATH is also broadcast, in step 308, to ATC and to any aircraft in the surrounding airspace.

100421 In the case where traffic exists on the calculated DIPATH flight path and a traffic collision is deemed possible at step 306, the additional distance Ad is increased, for example by Ad at step 309, so that the additional distance is iteratively recalculated Adn = n*Ad at step 310, to a maximum radius Adninx, which is a predetermined threshold distance, for example calculated based fuel availability on-board, or calculated by required arrival time at the end point and aircraft maximum speed. At each iteration, it is determined at step 311 whether Ad11a. has been exceeded, and if it has not, the process returns to step 304 and recalculates new lateral and vertical profile modifications, including an associated new DIPATH waypoint, based on the new additional distance. Although the additional distance is increased by integer multiples of Ad in this example, in alternative examples the distance may be increased by other factors of Ad, such as 0.54d, or by factors of a predetermined number of metres or kilometres, based on either aircraft or external constraints/requirements.

100431 In some examples, when traffic exists on the calculated DIPATH flight path and a collision is deemed possible at 306, an alternative DIPATH flight path may be determined in two directions for the same Ad. With reference to Figure 2a, waypoint B I is determined by travelling clockwise about waypoint A2; in these examples, alternative routes can be calculated for a waypoint reached by travelling anticlockwise about waypoint A2 100441 Figure 4 shows a simplified view of DIPATH results that are displayed to a pilot. The solid line represents an initial flight path (which may conform to a standard route) via a DIPATH start point Al and a merge point or DIPATH end point A2. The DIPATH has been iteratively calculated three times (n=3) as traffic is deemed to exist along the first DIPATH route (via B1) and the second DIPATH route (via B1 and B2). The system makes the pilot aware of the potential traffic, and the third DIPATH route, via B3 (i.e. Al 4B14B24B34A2) is either automatically or manually selected and applied by the system to the aircraft control system, such as an autopilot system. In calculating the second and third DIPATH routes, the processor 106 is arranged to determine a modified speed profile for the following aircraft to adapt alongside the lateral and vertical profile modifications, in order to ensure that the RTA is met despite the aircraft travelling a longer lateral distance than that of the first DIPATH.

100451 In an example, an aircraft approaching Al may expect its route along the initial flight path from Alto A2 to take 30 minutes. However, before reaching Al, the aircraft receives a request from ATC to arrive at A2 in 31 minutes, a required delay of 1 minute. The pilot may enable the D1PATH function to find a modified flight path that meets the required delay automatically, without requiring manual input. As a further advantage, the system 100 also provides improved separation management when used by a plurality of aircraft. For example, by dynamically managing the flight paths of multiple aircraft within a specified airspace the separation management can be improved, leading to increased safety and more efficient use of airspace. If three aircraft plan to travel between Al and A2 then by using the DIPATH procedure for all three aircraft, these aircraft can be spaced more efficiently on different DIPATH routes. The DIPATH procedure also allows an increased number of aircraft to be appropriately separated in the surrounding airspace. Thus, the system provides dynamic and/or automatic modification of the flight path of the aircraft to maintain the desired separation in terms of distance or time in an efficient manner, to enable efficient separation management of aircrafts in a specified airspace.

100461 In the case of heavy traffic in the surrounding airspace such that Adm., is exceeded and the DIPATH procedure is deemed not to be possible, the DIPATH algorithm will inform the pilot via the display, the pilot then disables the DIPATH procedure on the system 100 and can contact ATC at step 312 for guidance on the required separation management, alternatively, a request is be sent to ATC automatically by the system 100 100471 It is to be noted that the term "or" as used herein is to be interpreted to mean "and/or", unless expressly stated otherwise.

Claims

CLAIMS1 A system for determining a flight path modification to an initial flight path of an aircraft, the system comprising: a data receiver arranged to receive input data, the input data including: a start point and an end point representing spatial positions on the initial flight path; and time requirement data representing a time at which the aircraft is required to arrive at the end point; a processor arranged to analyse the received input data and to determine the flight path modification by calculating: i) based on the input data, a lateral profile modification to the initial flight path, and ii) based on the lateral profile modification, a vertical profile modification to the initial flight path, and a data output arranged to output data representing the flight path modification.
2. The system of claim 1, wherein the input data comprises speed data including at least one of: a current speed of the aircraft; an aircraft speed profile based on the initial flight path; and a speed requirement relating to at least a portion of the initial flight path; and wherein the processor is arranged to calculate a speed profile of the flight path modification based on the speed data
3. The system of claim 1 or 2, wherein the processor is arranged to: calculate the lateral profile modification by calculating a modified distance for the aircraft to travel from the start point to the end point; and based on the modified distance, calculate the vertical profile modification by calculating a modified angle of descent of the aircraft.
4. The system of claim 3, wherein the processor is arranged to determine, based on the modified distance, an additional waypoint via which the aircraft is required to travel, such that the direct distance between the waypoint and the end point is substantially equal to the direct distance between the start point and the end point.
5. The system of any of claim 3 or 4, wherein the input data comprises traffic data and the processor is arranged to: determine the existence of additional aircraft on the flight path modification; and determine an alternative flight path modification based on at least one of increasing the modified distance and changing a direction of travel to the additional waypoint.
6. The system of claim 5, wherein the processor is arranged to determine an alternative flight path modification by: increasing the modified distance for the aircraft to travel to the end point by a predetermined amount; based on the increased distance, recalculating the lateral profile modification; based on the lateral profile modification, recalculating the vertical profile modification by recalculating the modified angle of descent of the aircraft; and based on the recalculated lateral and vertical profile modifications, calculating the alternative flight path modification.
7. The system of claim 5 or 6, wherein the processor is arranged to iteratively determine alternative flight path modifications until a flight path modification absent of traffic is determined, or the processor determines that the increased distance exceeds the predetermined threshold distance
8 The system of any of claims Ito 7, wherein the system is arranged to apply the determined lateral and vertical path modifications to the aircraft.
9 The system of any of claims Ito 8, wherein the aircraft is a first aircraft, and the time requirement data is based on a required separation between the first aircraft and a second aircraft that is expected to arrive at the end point before the first aircraft
10. The system of any of claims Ito 9, wherein the system is on-board the aircraft.
11. The system of any of claims 1 to 9, wherein the system is ground-based
12. A computer-implemented method of determining a flight path modification to an initial flight path of an aircraft, the method comprising: receiving input data, the input data including: a start point and an end point representing spatial positions on the initial flight path; and time requirement data representing a time at which the aircraft is required to arrive at the end point; analysing the received data to determine the flight path modification by calculating: i) based on the input data, a lateral profile modification to the initial flight path, and ii) based on the lateral profile modification, a vertical profile modification to the initial flight path; and outputting data representing the flight path modification.
13. The computer-implemented method of claim 12, comprising: calculating the lateral profile modification by calculating a modified distance for the aircraft to travel from the start point to the end point; and based on the modified distance, calculating the vertical profile modification by calculating a modified angle of descent of the aircraft.
14. The computer-implemented method of claim 13, comprising determining, based on the modified distance, a waypoint via which the aircraft is required to travel, such that the direct distance between the waypoint and the end point is substantially equal to the direct distance between the start point and the end point
15. The computer-implemented method of any of claims 12 to 14, comprising: receiving speed data comprising at least one of: a current speed of the aircraft; an aircraft speed profile based on the initial flight path; and a speed requirement relating to at least a portion of the initial flight path; and calculating a speed profile of the flight path modification based on the received speed data.
16. The computer-implemented method of any of claims 12 to 15, wherein the input data comprises traffic data and the method comprises: (i) determining the existence of additional aircraft on the flight path modification; (ii) increasing the modified distance for the aircraft to travel to the end point by said modified distance; (iii) comparing the increased distance to a predetermined threshold distance, (iv) based on the increased distance, recalculating the lateral profile modification; (v) based on the increased distance, recalculating the vertical profile modification by recalculating the modified angle of descent of the aircraft; (vi) based on the recalculated lateral and vertical profile modifications, recalculating the flight path modification; (vii) determining the existence of additional aircraft on the recalculated flight path modification; and (viii) repeating (ii)-(vii) until either a flight path modification absent of traffic is determined, or the processor determines that the increased distance exceeds the predetermined threshold distance
17. The computer-implemented method of any of claims 12 to 16, comprising applying the determined lateral and vertical path modifications to the aircraft.
18. A computer program, or a suite of computer programs, which, when executed by a processing system, causes the processing system to perform the method according to any of claims 12 to 17
19. A computer readable storage medium, storing computer readable instructions thereon for execution on a computing system to implement the method according to any of claims 12 to 17.
20. A flight path modification system comprising: an input arranged to receive input data, the input data including: a start point and an end point representing spatial positions on an initial flight path; and time requirement data representing a time at which the aircraft is required to arrive at the end point; a processor arranged to analyse the received data and to determine a modification to the initial flight path by calculating, based on the input data, a modification to the flight path in a lateral direction and a vertical direction; and a data output arranged to instruct an aircraft control system to apply the modified flight path to the aircraft such that the time requirement is met.