FR2834057A1 - Aircraft navigation assistance device converts a time difference between a scheduled time of arrival and an ETA into a distance error so that a pilot can be made aware of any fuel shortages - Google Patents

Abstract

Navigation assistance device comprises: an error calculator (1) that determines an ETA for the aircraft at a destination (WPTRTA) for which a required time of arrival (RTA) has been established in advance by calculating a temporal error between the ETA and RTA; a converter then converts the temporal error into a distance error, based on the aircraft velocity; and a display (3) for the calculated distance error. The invention also relates to a corresponding aircraft equipped with such a system, a navigation assistance method and a computer program for implementation of the method. If the calculated distance error exceeds a threshold value, a spoken warning (4) is generated.

Description

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BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a navigation assistance apparatus for mounting in an aircraft, an aircraft in which the navigation assistance apparatus is mounted, a navigation assistance method and a navigation assistance processing program. navigation which is saved in a storage medium. In particular, the present invention relates to a four-dimensional or four-dimensional navigation method. The four-dimensional navigation method relates to navigation which includes management on the basis of time in addition to three-dimensional navigation which manages the state of an aircraft on the basis of latitude, longitude and altitude.

2. Description of the prior art
A conventional navigation assistance device is ready for three-dimensional navigation which manages the state of an aircraft on the basis of latitude, longitude and altitude. Three-dimensional navigation manages accuracy in terms of the position of an aircraft as well as the distance between aircraft. In order to manage the navigation accuracy of the aircraft, concepts of RNP (required navigation performance), ANP (actual navigation performance), etc. are used.

 A flight management computer or FMC which is mounted in an aircraft calculates the ANP based on data which are applied from a plurality of navigation sensors. The ANP values are monitored by the FMC itself or by a pilot using a multifunction control display unit or MCDU so as not to exceed the range defined by the RNP.

 The altitude of an aircraft is acquired by means of a GPS receiver, a radio altimeter or a barometric altimeter. Whether or not the aircraft maintains a target altitude is monitored by the pilot or by the FMC itself. The position of the aircraft along its trajectory (the direction in which the aircraft travels) is managed by reference to time so that, for example, an interval of at least two minutes is maintained between the aircraft and the previous aircraft. Consequently, in accordance with conventional navigation, the position of an aircraft is managed in three dimensions.

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 In recent years, air transport has been tightly planned to meet particular economic demands. It is certain that air traffic management by communication navigation monitoring or CNS / ATM will be introduced in air traffic management in the future. The introduction of CNS / ATM will further tighten air transport planning.

 Conventionally, however, flight intervals are managed with a large time margin in order to ensure safety.

This is disadvantageous with regard to increasing the efficiency of air transport.

 Under these circumstances, four-dimensional navigation which includes a time management factor in addition to the three-dimensional navigation factors has been proposed as a new concept of air traffic control. With this proposal, recent FMCs have been equipped with an RTA function (arrival time required). If air traffic control comes to include time management, the time margin can be minimized so that economical air service can be expected.

 Therefore, in recent years, there has been a social requirement to provide economical air service while maintaining a high level of security. As a result of these circumstances, the function of controlling time in aircraft management has been strengthened.

An important problem to be resolved in the air service is to establish the optimum flight interval for an aircraft along its trajectory by means of time management.

BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a navigation assistance device, an aircraft in which the navigation assistance device is mounted, a navigation assistance method as well as a navigation assistance processing program. navigation recorded on a storage medium which allow safe and economical air transport.

 A navigation aid device which is mounted in an aircraft, according to an aspect of the present invention, comprises: an error calculator (for example an arithmetic unit 1) which

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 obtains an estimated arrival time of the aircraft at which it is estimated that the aircraft will arrive at a target point for which a required arrival time of the aircraft is established in advance, by calculating a time error between the estimated arrival time and required arrival time; a converter (for example an arithmetic unit 1) which converts the time error which is calculated by the error calculator according to a distance error based on a speed of the aircraft; and a display (for example a display unit 3) which visually displays the distance error which is obtained by the converter.

 In addition, the display shows an aircraft symbol that represents the aircraft and an error symbol (for example, APTIME) that has a length that corresponds to the distance error.

 Using the means mentioned above, the difference between the estimated time of arrival at the target point (for example a point on the route) and the required time of arrival at the point is calculated using the error calculator. The converter calculates the distance error from the above-mentioned difference in time and from the speed of the aircraft. The display shows the distance error in the form of an error symbol or the like.

 Therefore, according to the present invention, the pilot of the aircraft can directly recognize the error in terms of the time that is required to arrive at the target point as a distance error. Therefore, flight safety can be ensured. In addition, the pilot can easily and appropriately keep the distance between the aircraft and the preceding aircraft so that economical air transport can be achieved.

 Additional objects and additional advantages of the invention will be highlighted in the description which follows and will appear in part more clearly from the description or can be learned by means of the practical implementation of the invention.

The objects and advantages of the invention can be achieved and obtained by means of the instruments and combinations more particularly highlighted below.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
The accompanying drawings which are incorporated herein

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 description and which constitute a part thereof represent embodiments of the invention and in association with the general description which has been presented above and with the detailed description of the embodiments presented below, they serve to explain the principles of the invention, and among these drawings: FIG. 1 is a diagram which represents an example of an aircraft 10 in which a navigation aid apparatus according to the present invention is mounted; FIG. 2 is a diagram which represents an example of an external view of a cockpit of the aircraft 10 which is represented in FIG. 1; Figure 3 is a block diagram showing the structure of a navigation assist apparatus according to an embodiment of the present invention; Figure 4 is a flowchart showing procedures in the navigation assist apparatus of Figure 3; Figure 5 is a diagram showing the relationship between WPTRTA, ETA, RTA and TIMEwpT; and Figure 6 is a diagram showing an example of an image which is displayed in a display unit 3 which is shown in Figures 2 and 3.

DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

 FIG. 1 is a diagram which represents an example of an aircraft 10 in which a navigation aid apparatus according to the present invention is mounted. The aircraft 10 is equipped with various navigation sensors such as INS (inertial navigation system), that IRS (inertial reference system), that GPS (global positioning system) and that DME (distance measuring equipment), none of these sensors only being shown.

 FIG. 2 is a diagram which represents an example of an external view of a cockpit of the aircraft 10 which is represented in FIG. 1. The cockpit comprises a display unit 3 which visually displays various pieces of information, a console which receives information which is entered by a pilot and an arithmetic unit which processes various types

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 of information.

 Figure 3 is a block diagram showing the structure of a navigation assist apparatus according to this embodiment.

This system is mounted in the aircraft 10 and it includes an arithmetic unit 1, an input unit 2, the display unit 3, a voice unit 4, a navigation sensor 5 and a clock unit 6.

 The arithmetic unit 1 is installed for example as part of the functions of an FMC. It controls the overall system through operating processes by means of a central processing unit or CPU. The input unit 2 which includes the console, a keyboard etc ... is used to enter various information. The display unit 3 is a liquid crystal or LCD display or the like. It visually provides various information to the pilot. The input unit 2 and the display unit 3 are implemented for example as parts of the function of an MCDU.

 The processing functions of the arithmetic unit 1 are implemented via a program which is recorded in a recording medium and which is executed by the CPU of the FMC. The recording medium can be of any type which can store computer programs, for example a readable semiconductor memory device, a recording medium for a magnetic recording device and a recording medium for a magneto-optical recording device. More specifically, the recording media may be a flexible disc, an optical disc, a magneto-optical disc, a phase change disc, a magnetic tape or the like.

 The voice unit 4 generates a warning message when necessary and calls the pilot's attention. The navigation sensor 5 includes for example an inertial navigation system or INS, the GPS, the DME, etc. and it applies information for a navigation calculation on the arithmetic unit 1.

 The clock unit 6 applies a current time to the arithmetic unit 1. The clock unit 6 is mounted on the front of an aircraft 10 as a cockpit clock or as a GPS receiver.

 Figure 4 is a flowchart showing procedures

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 a navigation aid device which has the structure which has been mentioned above. At a step 51 in FIG. 4, the pilot enters information such as a flight path, a target point to pass and a required arrival time (RTA) at the point, via input unit 2.

 In the following descriptions, a WPT RTA reference symbol represents a target point intended to be subject to time management. The arithmetic unit 1 calculates, by means of a step which is described below, an estimated time of arrival (ETA) at the target point as estimated from current situations by means of the assumption that l aircraft 10 continues the flight on the basis of the flight plan. The arithmetic unit 1 manages the flight of the aircraft 10 from a time aspect on the basis of the time difference between the ETA and the RTA.

 At a step S2, the arithmetic unit 1 calculates navigation data such as a position (POS) and a speed (VEL) of the aircraft 10, on the basis of the data which are applied from the navigation sensor 5. At a step S3, the arithmetic unit 1 calculates a time required to arrive at WPTRTA (TIMEwp-r) on the basis of the flight path which is entered at step 51 and the current speed of the aircraft 10 which is obtained in step S2. At a step S4, the arithmetic unit 1 obtains the current time from the clock unit 6. At a step S5, the arithmetic unit 1 calculates an ETA (an arrival time estimated at the level of WPTRTA) by means of the following equation (1) by adding the time TIMEwpT to the current time.

WPTRTA, ETA, RTA et TIMEwpT. ETA = current time + TIMEwPT (1)
Figure 5 is a diagram showing the relationship between

WPTRTA, ETA, RTA and TIMEwpT.

 TIMEwpT time is defined according to the flight path established at step 51.

At a step S6, in the flowchart which is represented in FIG. 4, an error at the time of arrival time ATime at the level of WPTRTA is calculated on the basis of the following equation (2):
ATime = RTA-ETA (2)
At an S7 step, the error in terms of arrival time

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ATime which is calculated in step S6 is converted according to an APTIME position error by means of the following equation (3): A? TIME = ATime x VEL (3)
At a step S8, the display unit 3 displays the position error APTIME which is calculated at the step S7 in association with the current position (POS) of the aircraft 10.

 FIG. 6 represents an example of an image which is displayed in the display unit 3. In FIG. 6, the hatched part corresponds to the position error APTIME. If the aircraft 10 is making a flight late with respect to a scheduled time at which the aircraft must arrive in an expected position, the position error. PTIME is displayed in front of an aircraft symbol along the direction of travel, as shown in FIG. 6. Furthermore, if the aircraft is making a flight ahead of the planned time, the APTIME position error is displayed behind the aircraft symbol.

 At a step S9, at the level of the flow diagram which is represented in FIG. 4, the arithmetic unit 1 compares the position error APTIME with a preset threshold value. If the APTIME position error exceeds the threshold value, the arithmetic unit 1 determines a warning level. At step S10, the arithmetic unit 1 determines whether or not a warning should be generated based on the result of the determination at step S9.

 If it is determined in step S10 that a warning must be sent on output, the voice unit 4 sends on output a warning information by means of a voice message at a step SU. According to a variant, the display unit 3 displays warning information. At this time, the form of output of the voice message (the tone of the voice or the content of the message read) as well as the reason for the displayed warning information (WARNING, ALERT, etc.) are modified. depending on the level of warning.

 At a step S12, the pilot determines whether or not a modification to the level of values initially entered is required. If a modification is not required, the procedures return to step S2. If a change is required, the procedures are restarted from

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 from step 81.

 The procedures are executed by means of software by means of the CPU (which is not shown) of the arithmetic unit 1 on the basis of a control program which is loaded in for example a random access memory or RAM. The procedures of steps 81 to S4 are generally implemented by means of a conventional FMC. The procedure of step 81 is executed at the level of an initial establishment while the procedures of steps 2 to 12 are executed periodically in real time.

 According to this embodiment, the arithmetic unit 1 calculates an estimated arrival time (ETA) at a target point and obtains a difference between the ETA and a required arrival time (RTA). The time error which corresponds to the difference in terms of time is multiplied by the speed of the aircraft, hence the conversion of the time error into a distance error. The distance error is displayed in terms of a symbol as APTIME on the display unit 3. As a result, the time error relating to the flight of an aircraft is visually displayed as an error of position. If the position error exceeds a predetermined threshold value, a warning such as a display message or a voice message is provided. The level of warning can be changed in steps according to the extent of the error.

 Therefore, the pilot can recognize an error in terms of time as an error in terms of distance at a glance. In other words, the pilot can receive notification of the time error as a position error in the horizontal direction. As a result, flight which maintains an appropriate distance between aircraft along the path (the direction of travel) is assisted. As a result, flight safety is improved.

 Furthermore, in accordance with this embodiment, the flight intervals of the aircraft can be reliably managed at the level of the aircraft itself. Consequently, the time margin of the flight intervals can be reduced, thereby shortening the distance between the aircraft. Consequently, the gain in air transport may be greater.

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 Furthermore, according to this embodiment, an error in terms of time of arrival at a desired point is converted according to a position error, very particularly on the basis of the ETA function of the flight management functions of the Classic FMC. Therefore, the structure to be added to the conventional system can be minimal, which results in a high degree of cost efficiency.

 In accordance with the conventional flight management system, it is necessary to modify the time margin in accordance with the type of aircraft. In contrast, according to this embodiment, since a time error is converted into a position error, aircraft of different speeds can be managed collectively. Therefore, all types of aircraft, from low speed aircraft such as helicopters to supersonic transport, can be managed on the basis of the same reference.

 As a result, economical air transport can be achieved while security is maintained.

 The present invention is not limited to the embodiment presented above. For example, the reason for the APTIME position error which is displayed in the display unit 3 is not necessarily rectilinear. In other words, if the preset flight path is curved as shown in Figure 5, the position error t1PTIME can be displayed as a curve along the flight path.

 At the flight service level of an aircraft, the RNP is established as the required precision index of a precision error and then the ANP is calculated as the estimated error. The threshold for determining whether or not to issue a warning can be modified according to a value of the ANP.

 Additional modifications can be made within the scope of the present invention.

 Additional advantages and modifications will be readily apparent to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments presented and described here. Therefore, various modifications can be made without departing from or

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 from the spirit or from the framework of the general inventive concept as defined by the appended claims and their equivalents.

Claims (14)

1. A navigation assistance device which is mounted in an aircraft (10), characterized in that it comprises: an error calculator (1) which obtains an estimated time of arrival (ETA) of the aircraft at which it is estimated that the aircraft will arrive at a target point (WPTRTA) for which a required arrival time (RTA) of the aircraft is established in advance, by calculating a time error between the estimated arrival time and the required arrival time (ATime); a converter (1) which converts the time error which is calculated by the error calculator (1) according to a distance error (APTIME) on the basis of an aircraft speed (VEL); and a display (3) which visually displays the distance error which is obtained by the converter (1).  2. A navigation assistance device according to claim 1, characterized in that the display (3) displays an aircraft symbol representing the aircraft and an error symbol having a length corresponding to the distance error ( APTIME) 3. Navigation assistance device according to claim 2, characterized in that the display (3) displays the error symbol either in front of the aircraft symbol, or behind this same aircraft symbol following the direction of movement of the aircraft in accordance with a sign of the time error (ATime) which is calculated by the error computer (1).  4. A navigation assistance device according to claim 2, characterized in that the display (3) displays the error symbol in association with a pre-established flight path of the aircraft.  5. navigation assistance device according to claim 1, characterized in that it further comprises a warning generator (4) which generates a warning if the distance error (APTIME) which is obtained at converter means (1) exceeds a threshold value.  6. navigation assistance device according to claim 5, characterized in that the warning generator (4) varies a <Desc / Clms Page number 12>  warning level per step according to a difference between the distance error (APTIME) and the threshold value.  7. navigation assistance device according to claim 5, characterized in that the warning generator (4) varies the threshold value in accordance with a precision of the distance error.  8. Aircraft (10) characterized in that it comprises: an error calculator (1) which obtains an estimated arrival time (ETA) of the aircraft at which it is estimated that the aircraft will arrive at a target point (WPTRTA) for which a required arrival time (RTA) of the aircraft is established in advance, which calculates a time error between the estimated arrival time and the required arrival time (ATime); a converter (1) which converts the time error which is calculated by the error calculator (1) according to a distance error (APTIME) on the basis of an aircraft speed (VEL); and a display (3) which visually displays the distance error which is obtained by the converter (1).  9. A navigation assistance method for use in an aircraft (10), characterized in that it comprises: a first step (S2-S5) to obtain an estimated arrival time (ETA) of the aircraft at which it is estimated that the aircraft will arrive at a target point (WPTRTA) for which a required arrival time (RTA) of the aircraft is established in advance; a second step (S6) for calculating a time error (ATime) between the estimated arrival time (ETA) which is obtained at the level of the first step and the required arrival time (RTA); a third step (S7) for converting the time error (ATime) which is calculated in the second step (S6) according to a distance error (APTIME) based on an aircraft speed (VEL); and a fourth step (S8) for visually displaying the distance error (APTIME) which is obtained in the third step (S7).  10. A method of navigation assistance according to claim 9, characterized in that the first step comprises: a fifth step (S2) to obtain a current position (POS) and a speed of the aircraft (VEL); a sixth step (S2) to calculate a distance to the point <Desc / Clms Page number 13>  target (WPTRTA) from the current position (POS) which is obtained at the level of the fifth step (S2); a seventh step (S3) to calculate a time required to reach the target point (WPTRTA) on the basis of the distance which is obtained at the level of the sixth step (S2) and the speed which is obtained at the level of the fifth step (S2); and an eighth step (S5) for adding the time which is required to arrive at the target point (WPTRTA), which is calculated at the level of the seventh step (S3), at a current time, hence the calculation of the time d estimated arrival (ETA).  11. A navigation assistance method according to claim 9, characterized in that it further comprises a ninth step (SU) for generating a warning if the distance error which is obtained at the third step ( S7) exceeds a threshold value.  12. A navigation assistance method according to claim 11, characterized in that it further comprises a tenth step for varying a level of the warning in steps according to a difference between the distance error (APTIME) which is obtained in the third step (S7) and the threshold value.  13. A navigation assistance method according to claim 9, characterized in that the steps from the first step to the fourth step (S2-S12) are repeated periodically.  14. A navigation assistance processing program recorded in a storage medium for controlling a computer (FMC) mounted in an aircraft (10), characterized in that it comprises: a command to cause the computer to carry out a first step (S2-S5) to obtain an estimated arrival time (ETA) of the aircraft at which it is estimated that the aircraft will arrive at a target point (WPTRTA) for which a required arrival time (RTA) aircraft is established in advance; a command to cause the computer to perform a second step (S6) to calculate a time error (ATime) between the estimated arrival time (ETA) which is obtained at the first step and the arrival time required (RTA); a command to make the computer perform a <Desc / Clms Page number 14>  third step (S7) to convert the time error (ATime) which is calculated in the second step (S6) according to a distance error (APTIME) based on a speed (VEL) of the aircraft (10 ); and a command to cause the computer (FMC) to perform a fourth step (S8) to visually display the distance error which is obtained in the third step (S7).