GB2227389A - Air traffic controller - Google Patents

Abstract

In an automatic air traffic management system aircraft fly in "tubes" each having a line 11 representing the normal assigned path of the aircraft, an inner boundary around a normal zone 13 representing acceptable deviations of the aircraft from the line 11, and an outer boundary around a warning zone 15. The system monitors the position of each aircraft and issues a warning to an air traffic controller if an aircraft leaves the normal zone 13 of its allotted tube, and a more urgent warning if it leaves the warning zone 15. This substantially relieves the air traffic controller of the need to monitor the aircraft to ensure that they remain within the tube, permitting the air traffic controller more time to devote to guiding aircraft into and out of tubes and through tube junctions, to maintaining correct spacing between aircraft along the tube, and to providing course correction instructions when aircraft arrive at bends in the tube. <IMAGE>

Description

AIR TRAFFIC CONTROL The present invention relates to air traffic control.

It has particular application to an automated, e.g.

computerised, air traffic management system intended to assist the work of an air traffic controller.

Commonly, an air traffic controller working in an air traffic control system is responsible for monitoring the positions and courses of a number of aircraft, and instructing the pilots of those aircraft to hold certain courses and make certain course changes. It is the job of the air traffic controller to ensure that each aircraft under his or her control passes through a region of controlled air space from its point of entry (e.g. an adjacent air space or a runway) to its desired point of exit (e.g. an adjacent air space or a runway) while at all times maintaining at least a certain minimum spacing from all other aircraft in the controlled air space. Typical minimum aircraft spacings, as required by the authorities which control the work of air traffic controllers, are 1,000 feet vertically and 3 miles horizontally.

In order to carry out this task, the air traffic controller must monitor the position, course and speed of all aircraft under his or her control, select courses which will take the aircraft to their desired destinations, and monitor both the present and predicted future separations between aircraft to ensure that the minimum separations between them are not infringed.

This task is complex and difficult, and computerised air traffic management systems have been provided to assist air traffic controllers. Such systems typically receive information about the positions of aircraft both from radar detectors and from frequent transmissions of current position from the aircraft, and provide a display to a controller of the positions and headings of all aircraft under his or her control.

These systems may also compute the separations between the aircraft and automatically provide a warning of potential conflict to the controller if any two aircraft are predicted to pass each other within less than a predetermined distance. The distance, at which a conflict warning is given, can be, but is not necessarily, the same as the required minimum spacing between aircraft which it is the controller's duty to maintain.

In order to make the air traffic controller's job easier, it has been proposed to divide a controlled air space hypothetically into a plurality of tubes or passages, connecting possible points of aircraft entry into the space to possible points of aircraft exit from the space. At least some aircraft flying through the controlled space would be required to fly along respective allocated tubes. There might be others, e.g. military aircraft, which would not normally fly in any tube, and for these aircraft all tubes would represent air space which was forbidden or could be entered only in accordance with special clearance procedures. Under such a system, an aircraft entering the controlled space might be allocated to a tube and required immediately to enter the tube. It would then be guided along the tube to its desired destination.In order to implement such a system in a practical manner, it will normally be necessary for the tubes to have some junctions to allow for the various different points of entry and desired points of exit which are possible through the air space.

The tubes are defined at least such that aircraft flying along tube centre lines cannot come within less than the minimum permitted spacing of aircraft flying along the centre line of any other tube. The tube dimensions and spacings are preferably defined such that aircraft directed to fly along tube centre lines should not come within the minimum permitted spacing of aircraft directed to fly along the centre line of any adjacent tube, taking into account the normal slight deviations of aircraft from-the paths to which they are directed. In paractice, the tubes may be defined to provide a greater spacing than this.The duty of the air traffic controller thus becomes (i) to monitor and control the correct positioning of each aircraft with respect to the centre line of its tube, (ii) to ensure that successive aircraft in the same tube are spaced by at least the required minimum distance, and (iii) to control the merging and splitting of streams of aircraft at tube junctions.

The present invention proposes to automate, at least in part, the first of these tasks, so as to leave the air traffic controller with more time to devote to the other two.

According to one aspect of the present invention, there is provided an automated air traffic control system in which data is stored defining one or more predetermined paths through an air space together with at least one predetermined degree of spacing from the path, the system allocating an aircraft to a path and monitoring its present and/or predicted position so as to give a warning if the said position varies from the allocated path by more than the or a said spacing.

The path data may be stored in any convenient form, such as data representing the path and data representing the magnitude and direction of the predetermined spacings, or alternatively data representing the positions of the boundaries of the predetermined spacings with or without the data representing the path itself. The path may be made up of a plurality of adjoining straight sections, and the three-dimensional co-ordinates of the ends of each section stored to define the path.

The magnitude of the spacings need not be the same in all directions from the predetermined path, and typically will be different in vertical and horizontal directions from the path. It is possible for the spacings to vary with position along the path, and also to be asymmetric. For example, if two paths pass very close to each other at one point, the boundary of a spacing may be close to its path in the direction towards the other path, since only very small deviations from the path in this direction can safely be permitted, but much further away in the opposite direction, in which larger deviations are safe Normally, the system will receive data indicating the current position, and preferably also the current course and speed, of aircraft in the space.

Preferably aircraft are allocated to the or a path, in accordance with allocation data input to the system.

The data relating to the aircraft is used to determine whether the aircraft is predicted to be about to cross a boundary. The prediction may be carried into the future until either the predicted course crosses a boundary or a maximum acceptable prediction time is reached. Alternatively, the prediction may be carried out for the maximum acceptable prediction time, and the predicted course examined to see if it crosses a boundary. The maximum acceptable prediction time is chosen as desired and may be influenced by the characteristics of the aircraft and the dimensions of the spacings around the path. It is preferably at least 30 seconds, and not normally more than 5 minutes. It might probably be 1 to 2 minutes.

The system may provide an output for the use of an air traffic controller, displaying the position of an aircraft about which a warning is being given, preferably together with data identifying the aircraft and possibly also with data providing a computed possible course correction instruction to be issued by the air traffic controller to the aircraft to return it to a course or position more closely in accordance with its allocated path.

In a preferred arrangement, the data defining a path defines more than one predetermined spacing, so as to define at least two levels of predetermined deviation from the path, one inside the other. In this way, the system is enabled to provide the air traffic controller with different levels of warning, as an aircraft moves or is predicted to be about to move beyond successive predetermined spacings from the path.

In such an arrangement, an inner spacing should normally be sufficient to include within it all normally expected deviations from the path in normal flight of an aircraft to which the path has been assigned. Preferably adjacent paths are arranged such that at the boundary of an inner spacing an aircraft is still at least the required minimum separation from an aircraft on an adjacent path. More preferably, the boundaries of inner spacings from adjacent paths are at least one required aircraft minimum spacing apart, and more preferably still the boundary of an outer spacing from-a path is at least one required aircraft minimum spacing from an inner spacing of an adjacent path.In this last arrangement, aircraft in adjacent paths cannot approach each other more closely than the required minimum spacing unless both simultaneously exceed the inner predetermined spacing from their respective paths.

In one embodiment of the present invention, the respective boundaries of outer spacings of adjacent paths are contiguous. In a preferred embodiment, there is a further safety zone separating the boundaries of outer spacings from adjacent paths.

In some cases, it may be preferable to select or define the boundaries of spacings around nearby paths by requiring that boundaries for adjacent paths have a certain separation from each other (which may not be equal to a required aricraft minimum spacing). This separation may be varied or kept fixed independently of changes in the separation between the paths themselves, with consequent variation in the widths of the spacings around the paths.

According to another aspect of the present invention, there is provided a method of air traffic control in which an aircraft is allocated to a predetermined path, having at least one predetermined level of permitted deviation, and the present or anticipated position of an aircraft is monitored automatically with respect to the permitted deviation or deviations from its allocated path and a warning is given if the said position exceeds a said deviation from the allocated path Embodiments of the present invention, given by way of example, will now be described with reference to the accompanying drawings, in which:: Figure 1 is a schematic diagram of a system embodying the present invention; Figure 2 shows a first cross-sectional arrangement of a plurality of flight tubes through a controlled air space; Figure 3 shows a schematic section through an alternative arrangement of flight tubes in a controlled air space; and Figure 4 shows an example of a display provided to air traffic controller by the system of Figure 1.

In the arrangement of Figure 1, a radio system 1 obtains data relating to the course (preferably including all of heading, angle of climb or descent, and speed) and position of an aircraft 3 both by radar location and by receiving location and course transmissions from the aircraft.

The radio system 1 passes the location data to a computer 5, in which are stored the paths of a plurality of flight tubes or passages through a region of controlled air space. The computer also receives input data from an input means 7, operated by an air traffic controller. The input means may include a keyboard, and also a "mouse", or rolling ball, or other similar computer input device. The data provided to the computer 5 by the air traffic controller through the input means 7 includes an allocation of particular aircraft to particular flight tubes.

In normal operation, each aircraft would be instructed to fly along the path defined by the centre line of its allocated flight tube. Each time the computer 5 receives data concerning the current course and position of an aircraft, it compares this with one or more previous courses and positions for the same aircraft and predicts a position for the aircraft a period of 2 minutes in the future. The computer stores as part of the definition of each flight tube, a plurality of tube boundaries one within another, and if the reported or predicted position of an aircraft is outside one of these boundaries, a warning display is given to an air traffic controller on a display means 9. The warning displays are different depending on which boundary of the flight tube the aircraft has or is predicted to have exceeded.

Figure 2 shows a schematic cross-section of one possible arrangement of flight tubes within the air space. Each flight tube has a centre line 11, which represents the ideal path of an aircraft in the flight tube. Around the centre line 11 is a normal zone 13, which is sufficiently large to permit an aircraft to deviate from the centre line 11 by the normally acceptable amounts of navigational, instrumental and piloting error. For example, the normal zone 13 may have a total height of 400 feet and a total width of 1.5 miles. Around the normal zone 13, there is a warning zone 15. Typically, this zone will be at least as large as the minimum permitted separations between aircraft, that is to say typically it will be at least 1,000 feet high and three miles wide.As shown in Figure 2, the warning zones of adjacent tubes are contiguous, so that aircraft flying along the centre lines 11 of adjacent tubes will maintain the required minimum spacing. Tubes are not permitted to overlap, so that provided each aircraft stays in its allotted tube, and the separation of aircraft along the tubes is maintained, aircraft cannot collide, and aircraft in adjacent tubes cannot come dangerously close to each other unless they both simultaneously stray out of their respective normal zones 13.

Figure 3 shows an alternative arrangement of tubes, in which each tube has a centre line 11, a normal zone 13 and a warning zone 15 in the same manner as Figure 2, and additionally a further safety zone 17 is provided around the warning zone 15. The total size of the safety zone 17 may be for instance 1,500 feet high and 5 miles wide. The presence of the safety zones 17 ensures that even if aircraft in adjacent tubes simultaneously move towards each other leaving their respective normal zones 13, a safe separation between them is still maintained.

In Figure 3, the safety zone 17 is shown as a defined zone having a boundary, and a further warning may be given if an aircraft leaves or is predicted to leave the safety zone. The safety zones of adjacent tubes are shown as contiguous. In an alternative arrangement, not illustrated, the outermost boundaries of adjacent tubes may not be contiguous but instead leave a region between them which does not belong to any tube.

In Figures 2 and 3, the normal, warning and safety zones are illustrated as being concentric around the centre line 11. However, this need not necessarily be the case.

A flight tube will typically be made up of a series of straight sections, having different directions, so that an aircraft has to make a course change when passing from one section to another. The tubes should be defined such that the required course changes can be accomplished by any aircraft which it is anticipated may use the tube, without leaving the normal zone 13. For this reason, the angle a between successive sections of a tube should preferably meet the requirement that COS(a/2) is no less than 1-(s/2r), where s is the width of the normal zone 13 and r is the minimum turning radius of an aircraft.

In one method of operation of the illustrated system, each tube is the responsibility of one particular air traffic controller. The air traffic controller will be presented with a display as shown in the lower part of Figure 4. This shows a plan view of the tube, with the centre line 11, normal zone 13 and warning zone 15 marked. Alongside the- representation of the tube, the tube heights are given at the ends of each straight section, and a gradient symbol 19 is provided to inform the air traffic controller whether the tube is climbing, level or descending.

The positions of aircraft allotted to the tube are shown by respective triangle symbols 21,23,25,27. Each triangle symbol is accompanied by a box 29,31,33,35 giving information about the respective aircraft, including an identification of the aircraft and its current course. A cross symbol 37 marks the location of a cursor, which can be moved by the air traffic controller using a mouse" or rolling ball computer input device.

The computer 5 receives updated aircraft position information at frequent intervals from the radio system 1, and uses this to update the positions of the triangle symbols 21,23,25,27 marking aircraft locations, and update the contents of the boxes 29,31,33,35 giving the aircraft courses. From this display, the air traffic controller can monitor the progress along the tube of the aircraft under his or her control, to ensure that they remain correctly spaced along the tube and to note when an aircraft approaches the end of a straight tube section, at which point the controller will have to issue a course change instruction to the aircraft.

The air traffic controller can use the mouse to move the cursor cross symbol 37 over the triangle symbol for an aircraft, so as to identify that aircraft, and can then press a key on a keyboard of the input means 7 to request a cross-section display of the position of that aircraft in the tube. The cross-section display for the aircraft corresponding to triangle symbol 25 is shown in the upper section of Figure 4.

The cross-section display shows a section through the tube at the position of the chosen aircraft, in the plane normal to the direction of the centre line 11 of the straight line section along which the aircraft is currently flying. The cross-section display shows the normal zone 13, the warning zone 15, the triangle symbol to mark the position of the aircraft and the information box 33 in the same manner as the plan view display of the tube in the lower section of Figure 4.

The computer 5, on receipt of aircraft position information from the radio system 1, calculates the current position of each aircraft with respect to its allocated tube, and uses the newly-received position information in combination with previous position information to calculate the course of the aircraft and predict a future position a short time, e.g. 1 minute, ahead. Provided that both the current and the predicted positions are within the normal zone 13, the computer 5 updates the displays provided to the air traffic controllers, but issues no warnings. However, if the present or predicted positions show that an aircraft has or is about to move out of the normal zone 13 or out of the warning zone 15, the computer 5 will issue a warning.There are four possible types of warning: current position exceeds normal zone; predicted position exceeds normal zone; current position exceeds warning zone; and predicted position exceeds warning zone. The computer 5 may also use this information to determine which direction an aircraft is going along the tube, and issue a warning if the aircraft is going the wrong way.

For each level of warning, the computer will give both a visual and an audible warning. The warnings that the warning zone 15 has been or is about to be exceeded will be more urgent than the warnings that the normal zone 13 has been or is about to be exceeded. Thus the visual display for exceeding the normal zone 13 will be to flash the relevant triangle symbol on the plan view display, whereas the display for exceeding the warning zone 15 will include both flashing the triangle symbol and changing its colour to red. Different sounds will be used for the audible warnings relating to the two different zones.

If, for example, the computer predicts that the aircraft represented by triangle symbol 25 is about to leave the normal zone 13, an audible warning will be given and triangle symbol 25 will be flashed. The air traffic controller then moves the cross symbol 37 representing the cursor position onto the flashing triangle symbol 25, and presses a key of the input means 7 to acknowledge the warning. In response to this acknowledgement, the computer mutes the audible warning and reduces the intensity of the flashing of the triangle symbol 25. The acknowledged warning continues to be given, at this lower intensity, until both the present and the predicted positions of the aircraft are once again within the normal zone 13.

The lower intensity warning will be replaced by a full intensity urgent warning if the aircraft exceeds or is predicted to exceed the warning zone 15. An acknowledged warning may also return to full intensity if the aircraft has not re-entered the normal zone 13 within a predetermined period of the acknowledgement.

Also in response to acknowledgement of the warning, a cross-section display of the tube and the aircraft about which the warning is given is provided as shown in the upper part of Figure 4. The triangle symbol 25 and the box 33 give the position of the aircraft and its identification and course. Additionally, an information box 39 at the bottom of the cross-section display displays a suggested instruction for the air traffic controller to give to the aircraft concerned, including a proposed new course calculated by the computer to correct the deviation of the aircraft from the centre line 11.

If the air traffic controller requests a tube cross-section display where no warning is being given, the display will be as shown in the top portion of Figure 4 except that the information box 39 will be absent.

In this way, the air traffic controller can devote most of his or her time and attention to ensuring that aircraft remain properly spaced along the tube, make the correct turns at junctions between straight sections of the tube, and pass through tube entrances, exits and junctions safely. Very little attention needs to be given to ensuring that aircraft remain within the tube, as this is monitored automatically by the computer 5 and the air traffic controller is alerted if an aircraft strays beyond the normal zone 13.

Various modifications and alternatives will be apparent to those skilled in the art. For example, in a simplified system the computer 5 would provide warnings only in response to the present position of each aircraft, and would not predict future positions.

In the illustrated system, two boundaries are given for the tube, one within the other, and different degrees of warning are given when different boundaries are exceeded. Other numbers of boundaries and respective warnings are possible, including a system having only one boundary for which a warning is given if it is exceeded, and systems are possible having several boundaries but in which the nature of the warning given is the same for exceeding different boundaries.

In a modification of the system, a warning is not necessarily given immediately that an aircraft leaves or is predicted to leave the normal zone 13. For example, if an aircraft leaves the normal zone for no more than thirty seconds, and its predicted course shows that it will re-enter the normal zone, no warning will be given. This avoids giving unnecessary warnings to the air traffic controller when an aircraft slightly cuts the corner between successive tube sections.

In order to minimise the number of course instructions which an air traffic controller has to give to an aircraft, the aircraft may be given the three-dimensional co-ordinates of each corner between straight path sections, and instructed to use these as waypoints. If these co-ordinates are stored in the aircraft's navigational system, it is only necessary to tell the aircraft which tube it is to enter. In this case, if the aircraft follows its instructions correctly no further course change instructions should be needed until the aircraft is to leave the tube or encounters a tube junction.

An alternative allocation of responsibilities between controller is also possible. Especially in an arrangement as just mentioned, when relatively few course correction instructions are required, one air traffic controller might be responsible for spacing aircraft along a tube, while another might be responsible for ensuring that aircraft remain within the tube cross-section. The automatic warnings that an aircraft is or is predicted to leave a tube would be given to the second controller. The displays for the controllers would be different from that shown in Figure 4, with each controller having displays appropriate to his or her task. The controller in charge of the tube cross-section might have sophisticated three-dimensional displays. This controller might be responsible for several different tubes simultaneously.

Claims (15)

CLAIMS:

1. An air traffic management system in which one or more paths, each having one or more boundaries, are defined in a region of space, and individual aircraft are allotted to respective paths, the system receiving data relating to the current and/or predicted position of an aircraft, comparing the said position with the allotted path of the aircraft, and providing a warning in at least one of the cases (i) that the aircraft has passed beyond a said boundary of the path, and (ii) that the aircraft is predicted to pass beyond a said boundary of the path.

2. A system according to claim 1, in which a warning is provided if the aircraft has passed beyond a said boundary of the path.

3. A system according to claim 1, in which a warning is provided if the aircraft is predicted to pass beyond a said boundary of the path.

4. A system according to claim 1, in which a warning is provided both if the aircraft has passed beyond a said boundary of the path and if the aircraft is predicted to pass beyond a said boundary of the path.

5. A system according to claim 4, in which different warnings are provided in the two said cases.

6. A system according to any one of claims 3 to 5, in which the system calculates the predicted position of the aircraft using the said data.

7. A system according to any one of claims 1 to 6, in which aircraft are allotted to paths on the basis of allocation data provided by an operator.

8. A system according to any one of the preceding claims, in which at least one said path has a plurality of boundaries, and warnings are given in respect of the passing and/or predicted passing of the aircraft beyond any of the said boundaries.

9. A system according to claim 8, in which different warnings are given in respect of the passing and/or predicted passing of the aircraft beyond different said boundaries.

10. A system according to claim 8 or claim 9, in which the said boundaries are concentric.

11. A system according to any one of the preceding claims, in which the warning is maintained in an altered form in response to an acknowledgement of the warning by an operator.

12. A system according to any one of the preceding claims, which displays, at least under some circumstances, the cross-section of a path together with an indication of the position of an aircraft relative to the cross-section.

13. An air traffic management method in which a plurality of paths, each having one or more boundaries, are defined in a space, aircraft are allocated to respective paths, the present and/or predicted positions of aircraft are determined, and a warning is given automatically if a said position of an aircraft is beyond a said boundary of its allocated path.

14. An air traffic management system substantially as herein described with reference to the accompanying drawings.

15. An air traffic management method substantially as herein described with reference to the accompanying drawings.