GB2630397A - Amending flight route to avoid restricted area - Google Patents

Abstract

A flight route 21 for an aircraft is modified by determining that it requires re-routing around a restricted airspace region 1; plotting an exclusion circle 11a containing the restricted airspace region; and amending the flight route so that it follows an arc 21b of the exclusion circle (and optionally transition segments 21a, 21c). E.g. a guide circle 11 may be obtained as the smallest circle containing all of the restricted airspace and centred on its geometric centre (15,Fig.2) and the exclusion circle may be concentric with the guide circle with a tolerance gap of 0.5 nautical miles. The rerouting may be due to the original flight route passing through the restricted airspace region and/or the exclusion circle. The altered route may be output to a flight control system as a commanded turn radius which equals the exclusion circle radius. This fixed turn radius is long and easy to follow at high speed.

Description

AMENDING FLIGHT ROUTE TO AVOID RESTRICTED AREA FIELD OF THE INVENTION

[0001] The present invention relates to a computer-implemented method of amending a flight route for an aircraft; a method of flying an aircraft; and an aircraft navigation system.

BACKGROUND OF THE INVENTION

[0002] US 2008/0051947 discloses a system and method for an aircraft which alerts a user of the aircraft of a possible entrance into a selected airspace. The flight path may then be altered, either by the user or automatically by a Flight Management Device (FMS) so that the airspace is not intruded upon during flight. In the altered flight path, a waypoint is removed and replaced with a new waypoint such that a segment of the flight route no longer intersects the airspace.

SUMMARY OF THE INVENTION

[0003] A first aspect of the invention provides a computer-implemented method of amending a flight route for an aircraft, the method comprising: a) determining that a flight route of an aircraft requires re-routing around a restricted airspace region; b) plotting an exclusion circle which contains all of the restricted airspace region; and c) amending the flight route so that it follows an arc of the exclusion circle around the restricted airspace region.

[0004] Optionally step a) comprises determining that the flight route of the aircraft passes through the restricted airspace region.

[0005] Optionally step a) comprises determining that the flight route of the aircraft passes through the exclusion circle.

[0006] Optionally the method further comprises outputting the amended flight route to a flight control system of the aircraft.

[0007] Optionally the amended flight route output to the flight control system comprises a commanded turn radius which is equal to a radius of the exclusion circle.

[0008] Optionally the exclusion circle is centred on a point in the restricted airspace region.

[0009] Optionally the point is identified by calculating a geometric centre of the restricted airspace region.

[0010] Optionally the step of plotting the exclusion circle comprises plotting a guide circle which contains all of the restricted airspace region; and plotting the exclusion circle so that it contains all of the guide circle, wherein the exclusion circle is concentric with the guide circle with a predetermined tolerance gap [0011] Optionally the method further comprises displaying the amended flight route.

[0012] Before being amended in step c), the flight route optionally passes through the exclusion circle.

[0013] Before being amended in step c), the flight route optionally passes through the exclusion circle and through the restricted airspace region.

[0014] Before being amended in step c), the flight route optionally passes through the exclusion circle and not through the restricted airspace region.

[0015] A further aspect of the invention provides a method of flying an aircraft, the method comprising: amending a flight route by a method according to the first aspect; and flying an aircraft on the basis of the amended flight route.

[0016] A further aspect of the invention provides an aircraft navigation system configured to amend a flight route by a method according to the first aspect.

[0017] A further aspect of the invention provides an aircraft comprising an aircraft navigation system according to the preceding aspect.

[0018] Optionally the aircraft further comprises a flight control system configured to fly the aircraft on the basis of the amended flight route.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Embodiments of the invention will now be described with reference to the accompanying drawings, in which: [0020] Figure 1 shows a restricted area and a guide circle crossed by a flight route; [0021] Figure 2 shows a restricted area and a guide circle centred on a geometric centre of the restricted area; [0022] Figure 3 shows an exclusion circle and interception points of the flight route; [0023] Figure 4 shows an amended flight route; [0024] Figure 5 shows a first alternative amended flight route; [0025] Figure 6 shows a second alternative amended flight route; [0026] Figure 7 shows an aircraft; [0027] Figure 8 shows navigation and flight control systems of the aircraft; [0028] Figure 9 is a flow diagram of a method according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT(S)

[0029] Figures 1 and 2 show a boundary of a restricted airspace region 1, and a flight route 20 of an aircraft passing through the restricted airspace region 1. A method of amending the flight route 20 will now be described.

[0030] First, a guide circle is plotted which contains all of the restricted airspace region 1. The guide circle may be plotted as shown in Figure 1, as shown in Figure 2, or in any other way. In the example of Figure 1, the guide circle 10 is the smallest circle that can be constructed which contains all of the restricted airspace region 1. In the example of Figure 2, the guide circle is plotted by identifying a point 15 in the restricted airspace region, then obtaining a guide circle 11 which is the smallest circle centred on the point 15 and containing all of the restricted airspace region 1. For example, the point 15 may be identified by calculating a geometric centre of the restricted airspace region 1. The method of Figure 2 is preferred because it is more computationally simple than the method of Figure 1.

[0031] Next an exclusion circle Ila is plotted so that it contains the guide circle 11 as shown in Figure 3. The exclusion circle 1 la is concentric with the guide circle 11 with a predetermined tolerance gap of (for example) 0.5 nautical miles [0032] After determining that the flight route 20 requires re-routing around the restricted airspace region 1, the flight route is amended so that it follows an amended flight route 21 shown in Figure 4. The amended flight route 21 comprises a transition segment 21a where the flight route 21 deviates away from the original straight flight route 20, a segment 2 lb where the flight route 21 follows an arc of the exclusion circle lla around the restricted airspace region 1, and a transition segment 21c where the flight route 21 deviates away from the arc and returns to the original straight flight route 20.

[0033] Hence the flight route 20 is amended in three steps: a) determining that the flight route 20 requires re-routing around the restricted airspace region 1; b) plotting an exclusion circle 11a which contains all of the restricted airspace region 1; and c) amending the flight route 20 so that it follows an arc of the exclusion circle lla around the restricted airspace region 1.

[0034] Figure 5 shows another example in which a flight route 30 is amended so that it follows an amended flight route 31. The amended flight route 31 comprises a transition segment 31a where the flight route 31 deviates away from the original straight flight route 30, a segment 31b where the flight route 31 follows an arc of the exclusion circle lla around the restricted airspace region 1, and a transition segment 31c where the flight route 31 deviates away from the arc and returns to the original straight flight route 30.

[0035] In the examples of Figures 4 and 5, each original flight route 20, 30 passes through the restricted airspace region 1. Hence, in these examples, the need for rerouting may be determined in step a) without first plotting the exclusion circle 11a. That is, step a) may comprise determining that the flight route 20, 30 of the aircraft passes through the restricted airspace region 1 [0036] Figure 6 shows another example in which a flight route 40 is amended so that it follows an amended flight route 41. The amended flight route 41 comprises a transition segment 41a where the flight route 41 deviates away from the original straight flight route 40, a segment 41b where the flight route 41 follows an arc of the exclusion circle Ila around the restricted airspace region 1, and a transition segment 41c where the flight route 41 deviates away from the arc and returns to the original straight flight route 40.

[0037] In the example of Figure 6, the original flight route 40 passes through the exclusion circle 1 la but not through the restricted airspace region 1. In this example, the need for re-routing may be determined in step a) after plotting the exclusion circle 11 a in step b). That is, step a) may comprise determining that the flight route 40 of the aircraft passes through the exclusion circle lla. Hence, in this example, step b) must be carried out before step a).

[0038] An aircraft 100 shown in Figure 7 comprises an in-flight navigation system shown in Figure 8. The in-flight navigation system comprises a display device 121 in a cockpit 102 of the aircraft, a user input device 125 such as a keyboard or touch screen, and a computer system 122. The computer system 122 is configured to display the flight route during flight of the aircraft on the display device 121, and issue appropriate commands to a flight control system 124 so that the aircraft 100 follows the flight route. The computer system 122 is configured to amend the flight route by implementing the method shown in Figure 9.

[0039] A navigation database 123 contains the boundaries of all restricted airspace regions. The navigation database 123 may be hosted on the aircraft 100, or it may be hosted on a server remote from the aircraft 100.

[0040] In steps 50-56 of Figure 9, the computer system 122 plots exclusion circles for all of the restricted areas in the database 123. For each restricted area, the restricted area is read from the database in step 51 and its geometric centre is calculated in step 52.

[0041] Next the distances to each of the boundary vectors of the restricted area are computed in step 53, and the maximum distance identified in step 54.

[0042] A tolerance of 0.5nm is added at step 55, and the boundary of the exclusion circle is plotted in step 56.

[0043] Steps 50-56 are repeated until there are no more restricted areas to cover.

[0044] Steps 50-56 may be completed before the flight of the aircraft, or at the beginning of the flight of the aircraft. During flight of the aircraft the computer system 122 continuously monitors the flight route. If an interception condition is identified at step 57 which indicates that the flight route will pass through an exclusion circle within 90 seconds, then steps 58-62 are implemented by the computer system 122.

[0045] Interception points between the flight route and the exclusion circle are identified in step 58. By way of example, Figure 3 shows the interception points 22a between the flight route 20 and the exclusion circle 11a. Next the curved segment 21b, 31b, 41b is plotted in step 59, and the transition segments 21a,c; 31a,c; 41a,c are plotted in step 60.

[0046] The amended flight route 21, 31, 41 is displayed on the display device 121 in step 61, and the amended flight route 21, 31, 41 is output to the flight control system 124 in step 62. The flight control system 124 then flies the aircraft on the basis of the amended flight route.

[0047] By way of example, the curved segment 21b, 31b, 41b may be output to the flight control system 124 as a waypoint (indicating the start of the curved segment), a turn radius which is equal to a radius of the exclusion circle 1 la, and a path length of the curved segment. The flight control system 124 operates control surfaces of the aircraft at the waypoint so that it turns at the commanded turn radius, and throughout the curved segment 21b, 31b, 41b the flight control system 124 continuously monitors the actual turn radius so that it remains at the commanded turn radius.

[0048] Optionally a similar process may be used by the flight control system 124 to follow the transition segments 21a,c; 31a,c; 41a,c of the amended flight route.

[0049] In the example of Figure 9, exclusion circles are plotted for all restricted areas before the flight, but in other embodiments an exclusion circle may be plotted "on the fly" only when an interception condition is identified (the interception condition determining that the flight route of the aircraft passes through a restricted airspace region in the next 90 seconds).

[0050] The amended flights routes 21, 31, 41 each have a segment 21b, 3 1 b, 41b which follows an arc of the exclusion circle 1 la around the restricted airspace region 1, and hence has a fixed turn radius (which is equal to a radius of the exclusion circle 11 a). This is advantageous in a number of ways. Firstly, the process of obtaining the exclusion circle ha is computationally simple and hence does not require a large amount of computing power onboard the aircraft. Secondly, the fixed turn radius is relatively long which makes it easy for the aircraft to follow at high speed. Thirdly, it enables the restricted area to be avoided without adding excessively to the length of the flight route.

[0051] Where the word 'or' appears this is to be construed to mean 'and/or' such that items referred to are not necessarily mutually exclusive and may be used in any appropriate combination.

[0052] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims (16)

1. CLAIMS1 A computer-implemented method of amending a flight route for an aircraft, the method comprising: a) determining that a flight route of an aircraft requires rerouting around a restricted airspace region; b) plotting an exclusion circle which contains all of the restricted airspace region; and c) amending the flight route so that it follows an arc of the exclusion circle around the restricted airspace region.
2. 2. A method according to claim 1, wherein step a) comprises determining that the flight route of the aircraft passes through the restricted airspace region.
3. 3. A method according to claim 1, wherein step a) comprises determining that the flight route of the aircraft passes through the exclusion circle.
4. 4. A method according to any preceding claim, further comprising outputting the amended flight route to a flight control system of the aircraft.
5. 5. A method according to claim 4, wherein the amended flight route output to the flight control system comprises a commanded turn radius which is equal to a radius of the exclusion circle.
6. 6. A method according to any preceding claim, wherein the exclusion circle is centred on a point in the restricted airspace region.
7. 7. A method according to claim 6, wherein the point is identified by calculating a geometric centre of the restricted airspace region.
8. 8. A method according to any preceding claim, wherein the step of plotting the exclusion circle comprises plotting a guide circle which contains all of the restricted airspace region; and plotting the exclusion circle so that it contains all of the guide circle, wherein the exclusion circle is concentric with the guide circle with a predetermined tolerance gap.
9. 9. A method according to any preceding claim, further comprising displaying the amended flight route.
10. 10. A method according to any preceding claim, wherein before being amended in step c), the flight route passes through the exclusion circle.
11. 11. A method according to any preceding claim, wherein before being amended in step c), the flight route passes through the exclusion circle and through the restricted airspace region.
12. 12. A method according to any of claims 1 to 10, wherein before being amended in step c), the flight route passes through the exclusion circle and not through the restricted airspace region.
13. 13. A method of flying an aircraft, the method comprising: amending a flight route by a method according to any preceding claim; and flying an aircraft on the basis of the amended flight route.
14. 14. An aircraft navigation system configured to amend a flight route by a method according to any of claims 1 to 12.
15. 15. An aircraft comprising an aircraft navigation system according to claim 14.
16. 16. An aircraft according to claim 15, further comprising a flight control system configured to fly the aircraft on the basis of the amended flight route.