Method for approaching a platform

0001The present invention relates to a method for driving an aircraft on a platform, and in particular a short-landing aircraft such as an aircraft equipped with a rotary wing for example.

0002The invention thus lies in the technical field of systems for assisting the piloting of an aircraft, and in particular automated systems for assisting approaching rotorcraft platforms.

0003Indeed, a rotary-wing aircraft must be able to find and safely approach mobile platforms or vessels, regardless of weather and visibility conditions and avoiding obstacles in the approach area.

0004The approach is carried out taking into account the direction and speed of the wind in the sector, the type of platform to be approached (fixed platforms, mobiles, boats or barges), surrounding obstacles (cranes, barges, positioning boats Of the platform, vessels type container holders or "super tanker" sailing around the approach area, or other surrounding platforms), comfort of the passengers.

0005Platform approaches generally consist of the following flight segments.

0006The approach thus comprises an arrival segment which connects the last flight point of the current flight phase and an initial approach point known by the acronym "IAF" as "Initial Approach Fix" in English. This arrival segment is generally positioned at an altitude of 1500 ft. It is recalled that the symbol "ft" refers to the unit of length denominated "feet" in English language equal to 30.48 centimeters.

0007An initial approach segment can link the initial IAF approach point to an intermediate point known as IF "Intermediate Fix" in English. This initial approach segment aims to allow the aircraft to decelerate and align with the trajectory to be followed.

0008An intermediate approach segment can link the intermediate point IF to a final approach point known as "FAF" or "Final Approach Fix" in English to descend to an altitude up to 1000 ft. The purpose of this segment is to align the aircraft, decelerate and prepare the final approach segment.

0009At least one final approach segment connects the final FAF approach point and a decision point known as "MAP" or "Missed Approach Point" in English.

0010For example, the final approach point FAF is connected to the decision point MAP via an LPO bearing point and an OIP offset point.

0011If a pilot makes visual contact with the platform at the decision point, the pilot may place the aircraft on that platform.

0012On the other hand, a so-called go-around segment must be conducted if visual contact with the platform is not obtained at this stage of the approach. This segment of the go-around may also be conducted at any time during the approach if the crew deems it useful. The object of this go-around segment is to reach a safe altitude.

0013The final descent from the final approach point to the MAP decision point should not be carried out except in the absence of obstacles in a 2 nm corridor. It is recalled that the symbol "nm" refers to the unit of length denominated "nautical mile" in English language worth 1852 meters.

0014If obstacles are present in this corridor, the approach procedure may be canceled by security. The detection of such obstacles can be tricky. Indeed, a crew may have difficulty in assessing whether the presence of a moving ship is likely to terminate the approach procedure.

0015The following documents present known approaches to platforms:<ul><li>the document <nplcit id="ncit0001" npl-type="s"><text>AC90-80B "Approval of Offshore Standard Approach Procedures, Airborne Radar Approaches, and Helicopter Descent Areas Descent Areas" published on 12.04.99</text></nplcit></li><li>the document <nplcit id="ncit0002" npl-type="s"><text>JAR OPS 3, Section 2, Subpart E IEM to Appendix 1 to JAR-OPS 3.430 sub-paragraph (d) (amendment 2, published 01.01.02</text></nplcit>).</li><li>the document <nplcit id="ncit0003" npl-type="s"><text>EU-OPS COMMISSION REGULATION (EU) No 965/2012 of 5 October 2012 (AMC1 CAT.OP.MPA.120 and GM1 CAT.OP.MPA.120</text></nplcit>)</li><li>the document <nplcit id="ncit0004" npl-type="s"><text>CAA paper 2010/01 "The SBAS Offshore Approach Procedure (SOAP)</text></nplcit>".</li></ul>

0016When the weather conditions are unfavorable, an instrument approach is conducive to the stress of the crew, who must manually pilot the aircraft to guide it to an area where visual acquisition of the platform will be achieved.

0017In the transition between the instrument flight phase and the visual flight phase, the crew's attention must constantly shift between what is displayed on the dashboard control screens and what it observes The outside to detect any visual sign / index to confirm the position of the platform (light, relief). This approach to platform is therefore not the most practical and can sometimes create errors of interpretation in case of fog temporarily losing the visual acquisition of the landing target.

0018Instrument approaches to a mobile platform or vessels have so far been conducted without the use of a navigation computer known as FMS or Flight Management System in English and without coupling to the pilot Automatic control of the aircraft on an approach path predefined by the FMS.

0019Some platforms are now equipped with a device known as "NDB" or "Non Directional Beacon" in English, used by the crew via the navigation computer as a means of aids to navigation and Correlation of the position of the apparatus with relative accuracy but this means does not allow the construction of an approach flight plan.

0020A navigation computer is known to provide horizontal guidance during the en-route phase. For the approach phase, the crew determines an off-road target point corresponding to the coordinates of the platform to be reached as a means of aid to navigation. However, the navigation computer does not segment the different phases of the approach to the platform in order to control the autopilot on these guiding data (horizontal deviation, vertical deviation, speed reference).

0021The approach is then conducted manually or semi-automatically via the assistance of certain upper modes of the autopilot using the approach charts published by the operators and approved by the local authorities.

0022The weather radar of the aircraft may also be used as a means of identifying the platform, detecting and avoiding a transient or fixed obstacle during the approach and final descent.

0023The document <patcit id="pcit0001" dnum="US20100168939A"><text>US 2010/0168939</text></patcit> Proposes a module and an automated method of approaching a platform on an approach trajectory constructed from approach points.

0024According to this document <patcit id="pcit0002" dnum="US20100168939A"><text>US 2010/0168939</text></patcit>, A pilot enters in a module of the aircraft:<ul><li>The coordinates of the target platform to be reached,</li><li>A final approach heading towards the platform,</li><li>An offset distance laterally separating the trajectory to be traced from a trajectory directed towards the platform along this approach heading,</li><li>A height of descent.</li></ul>

0025Consequently, the module of the aircraft determines in particular the position of the initial approach point IAF and the final approach point FAF in response to the data entered. The aircraft is then directed towards the starting point of approach.

0026Thus, the constructed approach trajectory comprises a horizontal segment connecting an initial approach point IAF to a final approach point FAF.

0027Then, the trajectory comprises a descent segment and then a step segment to connect the final approach point FAF to a decision point MAP.

0028The initial approach point IAF, the final approach point FAF and the decision point MAP are contained in a vertical plane parallel to the chosen approach heading. It is understood that a vertical plane is called a plane directed according to gravity, points of this vertical plane being able to be at different altitudes.

0029This vertical plane is offset with respect to the platform by a distance equal to the offset distance entered.

0030The document <patcit id="pcit0003" dnum="US7016772B2"><text>US7016772 B2</text></patcit> Discloses a device for displaying information on vehicles according to their importance (size, position, speed) and discloses a ship system which combines radar information with information from an automatic identification system known under the Acronym "AIS" or "Automatic Identification System" in English.

0031The document <patcit id="pcit0004" dnum="US8296001B1"><text>US8296001 B1</text></patcit> Unveils a system that assists a browser by giving the characteristics of other boats and coastal information. A radar or AIS system may be used.

0032The document <patcit id="pcit0005" dnum="JP3763004B"><text>JP3763004 B1</text></patcit> Describes a system for protecting a downhill plan approaching an aircraft to an airport with an AIS system.

0033The technological background also includes the following documents:<ul><li>Esterline CMC Electronics, CMA-9000 Flight Management System Operator's Manual, S / W 169-614876-022, Publication No. 9000-GEN-0105, itel N). 930-6000088-00, august 21.2008</li><li><nplcit id="ncit0005" npl-type="s"><text>N.McFarlane, A new procedure for North Sea Helicopter Operations, Second GIANT use forum, Brussels, Belgium, October 9, 2008</text></nplcit>,</li><li><nplcit id="ncit0006" npl-type="s"><text>KM Dodson and JR Stevens, A North Sea Trial to Investigate the Use of Differential GPS for Instrument Approaches to Offshore Platforms, Paper presented at the 23rd European Rotorcraft Forum, Dresden, Germany, September 1997</text></nplcit>,</li><li>The documents <patcit id="pcit0006" dnum="EP2249126A"><text>EP 2249126</text></patcit>, <patcit id="pcit0007" dnum="GB2492665A"><text>GB 2492665</text></patcit>, <patcit id="pcit0008" dnum="FR2943778"><text>FR2943778</text></patcit>.</li></ul>

0034The object of the present invention is thus to propose an approach method intended to help a crew to land on a platform with an aircraft.

0035According to the invention, a method for facilitating the approach of a platform present on a liquid surface with an aircraft comprises an elaboration phase for elaborating an approach trajectory towards a theoretical position of said platform.

0036In addition, this method may include a consolidation phase, or a security phase, or a consolidation phase and a security phase.

0037During the consolidation phase of said approach trajectory:<ul><li>∘ determining the current position of said platform,</li><li>∘ determining a distance separating said theoretical position from said current position,</li><li>∘ an alert is triggered when said distance is greater than a first threshold,</li></ul>

0038During the phase of securing said approach trajectory:<ul><li>∘ the current position and the direction of travel and the speed of movement of the objects provided with an automatic identification system which are present in a predetermined monitoring zone are determined over time,</li><li>∘ a level of dangerousness of each object is determined with respect to the approach trajectory followed,</li><li>∘ a horizontal representation of said approach trajectory, as well as for each object, is displayed on a display screen: a plot representing the current position of the object, an indication of the direction of movement of the object, and a relative representation To the level of dangerousness of the object.</li></ul>

0039Monitored objects can be floating objects and / or flying objects.

0040The elaboration phase can be undertaken automatically by a navigation computer, starting from input data including in particular the theoretical position of the platform and an approach stroke such as a course to be followed, for example. Reference is made to the literature on the approach procedures that can be generated.

0041The theoretical position can be entered by an operator, or can come from a database of platforms. This database includes, for example, an identifier of the platform and these coordinates. Other information is possibly present, such as a radius of each platform, especially considering that each platform is contained in a circle.

0042The consolidation phase proposes to compare the theoretical position of a target platform that has established the approach trajectory at a current position of this target platform. Thus, a radar signal or a signal known by the acronym AIS referring to an automatic identification system makes it possible to obtain a "measured" current position of the target platform.

0043If the distance separating the theoretical position from the current position is less than a first threshold, the coordinates of the theoretical position are considered to be accurate. The first threshold may be of the order of 0.1 Nm.

0044On the other hand, if not, an alarm is generated to warn the crew and report a possible problem. It will be seen hereinafter that the crew may then divert or may set the approach trajectory to a new position of the platform, for example the current position.

0045It is understood that the aircraft makes measurements at a given frequency. For example, the aircraft may report positions transmitted by automatic identification systems every 6 seconds during a forward flight.

0046Consequently, an alert can be generated only if a plurality of measurements confirms the offset present between the theoretical position and the current measured position.

0047The consolidation phase can be carried out automatically and in real time by a computer, such as a cartographic computer known by the acronym DMAP communicating with the navigation computer.

0048This consolidation phase makes it possible to secure the approach favorably.

0049Moreover, this method can implement a security phase. Some regulations require the aircraft to follow an approach course in a 2-nm wide approach corridor centered on this approach path, this approach corridor not having to contain any obstacle.

0050It may be tricky to verify this point during instrument flight in adverse weather conditions using only weather radar as the primary means of identification and obstacle detection. The security phase tries to remedy this for obstacles including automatic identification systems.

0051These automatic identification systems transmit information to the aircraft relating to the obstacle, such as its position and its speed vector. With the aid of this information, the dangerousness of the obstacle is determined by determining the risks of conflict between the trajectory of the aircraft and the trajectory of the obstacle. This operation is carried out, for example, for each obstacle present in the surveillance zone under consideration. Consequently, the visualization trajectory followed by the aircraft, as well as identifiers allowing visually to determine the position of an obstacle, the movement effected by this obstacle, the dangerousness of the obstacle by Relative to the calculated approach trajectory or even the predictive position of the obstacle to the

0052With this information, an aircraft crew member can establish an alternative approach path if an obstacle is likely to be present in the current approach corridor. The aircraft may also divert if necessary.

0053The method may further include one or more of the following additional features.

0054Thus, during the consolidation phase and if the distance separating the theoretical position from the current position is less than a second threshold, the theoretical position of the platform can be modified manually. The second threshold may be greater than the first threshold.

0055For example, the theoretical position of the platform is modified to minimize the distance separating it from the current raised position by making it coincide with the current position, if any. The new theoretical position is then used to establish the approach trajectory, for example by a navigation computer.

0056For example, a new theoretical position can be chosen by using a cursor displayed on the display screen, such as a cross of Saint Andrew for example. This cursor can point to the current position displayed on this display screen for example. It is also possible to enter a distance and an axis on a navigation computer to reset the theoretical position of the platform. Finally, it will be possible to use an automatic AIS identification system of the platform to adjust the theoretical position of the platform on its AIS coordinates.

0057It should be noted that the registration of the platform is authorized only if the determined distance is less than the second threshold, for example of the order of 0.3 nm. This feature aims at avoiding random resetting in the event of a too large difference between the theoretical position and the current position.

0058As an alternative, the registration can be authorized independently of the value of this distance.

0059This registration can induce an automatic calculation of a new approach trajectory.

0060Thus, it is possible to automatically determine a vector linking the theoretical position of the platform to a new target position, and the approach path is automatically shifted by applying this vector to the said new position.

0061Recalibration may be prohibited if it occurs too late in the approach procedure. The manufacturer may determine an approach point from which registration is prohibited.

0062In addition, the consolidation phase can be started upon receipt of information providing the current position of the platform. For example, the consolidation phase begins when the aircraft receives information from an automatic platform identification system.

0063In addition, the predetermined monitoring zone is possibly a circle of a radius defined by the manufacturer centered on the platform to be reached.

0064This radius may correspond to the length separating an initial approach point IAF of the target platform plus a constant, of the order of 0.5 nm for example.

0065In addition, an approach lane of a given width centered on said approach trajectory can be displayed on the display screen. The width can be 2 nm according to certain regulations. The approach corridor may then be the approach corridor described in these regulations, possibly extended locally for safety.

0066Furthermore, the approach trajectory may include a final approach point FAF

0067Therefore, during the safety phase, the approach trajectory passing through a final approach point FAF, before this final approach point FAF is reached by the aircraft:<ul><li>The time necessary for said aircraft to reach this final approach point FAF is determined,</li><li>Determining the predictive position that each of said objects will have when said aircraft has reached the final approach point,</li><li>The level of dangerousness of each object is determined as a function of its predictive position and its current position with respect to an approach corridor of a given width centered on said approach trajectory.</li></ul>

0068For example, a first, second and third levels of dangerousness are implemented, an object being associated:<ul><li>At the first level of dangerousness when the current position of that object is not located in said approach corridor and when its predictive position will not be located in said approach corridor when said aircraft has reached the final approach point,</li><li>At the second level of dangerousness when the current position of that object is not located in said approach corridor and when its predictive position will be located in said approach corridor when said aircraft has reached the final approach point,</li><li>To the third level of dangerousness when the current position of that object is located in said approach corridor and when its predictive position will be located in said approach corridor when said aircraft has reached the final approach point</li></ul>

0069If an object presents the first, second, or third level of dangerousness, a first, a second or a third representation is respectively displayed. For example, each representation corresponds to the color of the plot. A white colored stud can signal a non-hazardous object with the first level of danger, a hatched or colored stud in amber may signal a potentially dangerous object with the second level of danger, and a stud colored red or black may signal a Dangerous object presenting the third level of dangerousness.

0070Moreover, depending on the detected objects, it is possible to allow a change of stroke of said approach trajectory during an elaboration phase of an alternative approach trajectory.

0071In the presence of dangerous objects, for example, an operator develops an alternative approach trajectory by choosing a new approach course. If the approach path has a segment offset to the right of the platform with respect to an initial segment, the operator can also choose an offset to the left of this platform, and vice versa.

0072The first approach trajectory and the alternative approach trajectory can be displayed on the display screen with separate representations to facilitate the development of the alternative approach trajectory.

0073For example, the current approach trajectory is displayed in solid lines, and the alternative approach trajectory in dotted lines. Alternative approach corridor can also be displayed.

0074In addition, during the safety phase, the approach trajectory passing through a final approach point FAF, after this final approach point FAF is reached:<ul><li>The current position as well as the predictive position based on the direction of travel and the speed of movement of the objects referred to as "intruders" located in front of said aircraft or in a circle centered on said aircraft and having a predetermined diameter are determined over time,</li><li>For each intruder and over time:<ul><li>∘ determining whether said intruder is at a current time located in an approach lane surrounding said approach trajectory and if said intruder is located in front of the aircraft,</li><li>∘ if the intruder is not present in the approach lane and if the intruder is located in front of the aircraft, it is determined whether the intruder will enter the approach lane in the future and, if so, When said intruder enters the approach corridor,</li><li>∘ associating said intruder with a first level of dangerousness represented by a first representation on the display screen when said intruder is behind the aircraft at a current instant or when said intruder will be behind the aircraft when it enters said corridor approach,</li><li>∘ said intruder is associated with a second level of dangerousness represented by a second representation on the display screen when said intruder is in front of the aircraft when it enters said approach lane,</li><li>∘ associating said intruder with a third level of dangerousness represented by a third representation on the display screen when said intruder is in front of the aircraft in said approach lane at the current instant.</li></ul></li></ul>

0075Normally, no obstacle should be in the approach corridor at this stage. However, a vessel or an aircraft may have changed course, and this process may make it possible to estimate a danger not originally foreseen.

0076This procedure makes it possible to quantify the possible risks associated with such obstacles.

0077In addition, according to a variant:<ul><li>A moving box representing a quadrilateral with a predetermined fixed width and a length equal to the product of a time constant and the ground speed of the aircraft is displayed on the display screen, the mobile box being centered transversely On the speed vector of the aircraft and extending longitudinally from a representation of the aircraft,</li><li>The current position as well as the direction of displacement, the traveling speed and the predictive location at the end of the said time constant of the objects referred to as "close-up" located on the said liquid surface provided with an automatic system Which are present in a predetermined scanning area centered on said aircraft,</li></ul><ul><li>We display on the visualization screen for each close element:<ul><li>∘ a first symbology when the current position and the predictive location are not located in the moving box,</li><li>A second symbology when the present position is not located in the moving box and when the predictive location is located in the moving box,</li><li>A third symbology when the present position is located in the moving box and when the predictive location is not located in the moving box,</li><li>∘ a fourth symbology when the current position and the predictive location are located in the moving box.</li></ul></li></ul>

0078The mobile box provides information to a pilot on the short-term situation to come.

0079This warning information on the potential risk of an obstacle between the trajectory of the aircraft and the trajectory of the moving obstacle may take account of either the current speed of the aircraft or the speed instructions followed by default by the user, Aircraft along the predicted approach trajectory.

0080It is recalled that each object is schematized on the display screen using the following visual identifiers: a plot, an indication of the direction of movement of the object and a representation relating to the level of dangerousness of the object through Of coloration of the stud for example, or even an indication of a predictive position of the object at the end of a given time. This indication of the direction of displacement may be an arrow whose length depends on the speed of movement of the object, the arrow being able to result in a predictive position of the object at the end of a given time predetermined by the manufacturer.

0081The aforementioned symbologies may comprise identifiers of another type, or may consist in modifying at least one of these identifiers.

0082For example, the first symbology may not modify said identifiers. On the other hand, the second symbology may cause the said arrow to flash, the third symbology may cause a block to flash, and the fourth symbology may cause the block and the arrow representing an object to flash.

0083BRIEF DESCRIPTION OF THE DRAWINGS The invention and its advantages will appear more fully in the context of the following description with exemplary embodiments given by way of illustration with reference to the accompanying drawings, in which:<ul><li>the <figref idrefs="f0001">figure 1</figref>, A diagram showing an aircraft implementing the method according to the invention,</li><li>the <figref idrefs="f0001">Figure 2</figref>, A diagram explaining the safety phase when the aircraft has not reached the final approach point,</li><li>the <figref idrefs="f0002">Figure 3</figref>, A diagram explaining the safety phase when the aircraft has reached the final approach point,</li><li>the <figref idrefs="f0002">FIG. 4</figref>, A diagram explaining the consolidation phase,</li><li>the <figref idrefs="f0003">FIG. 5</figref>, A diagram showing the displayed moving box, and</li><li>the <figref idrefs="f0003">Figure 6</figref> A vertical representation of the trajectory followed.</li></ul>

0084The elements present in several distinct figures are assigned a single reference.

0085The <figref idrefs="f0001">figure 1</figref> Presents an aircraft 1 capable of implementing the method according to the invention.

0086This aircraft may comprise a navigation computer 2, such as a computer commonly known by the acronym "FMS" and the English expression "Flight Management System".

0087This navigation computer 2 can communicate with a database 3 listing platforms and certain characteristics of these platforms.

0088In addition, the navigation computer is in communication with an automatic guidance device 10 able to guide the aircraft along an approach path elaborated by the navigation computer.

0089This navigation computer can generate an approach trajectory to reach a target and in particular a platform floating on a liquid surface and can transmit instructions to the automatic guidance device so that the aircraft is guided on this approach trajectory .

0090In addition, the aircraft 1 is provided with a cartographic calculator, such as a computer known by the acronym "DMAP" or the expression "Digital Map".

0091The cartographic calculator 4 is connected to an automatic identification system 5 known by the acronym "AIS" or the expression "Automatic Identification System". The automatic identification system 5 can receive AIS signals from objects equipped with a similar system. These AIS signals can provide the current latitude and longitude of the object, its speed of movement, its direction of travel, its height, its draft ...

0092The cartographic calculator 4 can be connected to an automatic identification system 5 known by the acronym "TCAS" or the expression "Traffic Collision Avoidance System". The automatic identification system may receive TCAS signals from other aircraft equipped with a similar system. These TCAS signals can provide the distance between the aircraft and the intruder aircraft, as well as the following information relating to the intruder aircraft: altitude, vertical speed, relative stroke, current latitude and longitude, and movement speed.

0093It is understood that the aircraft may comprise an automatic identification system using AIS technology and / or TCAS technology in particular.

0094In addition, the cartographic calculator 4 can communicate with a radar system 6 so as to receive echoes from radars and commonly referred to as "radar echoes".

0095The cartographic computer 4 is capable of generating displays having, in particular, the received radar echoes and the objects identified by the automatic identification system 5.

0096The navigation computer 2 and the cartographic calculator 4 are in communication with a display device 7. The display device is provided with a display screen and buttons 9 or the equivalent maneuverable by an operator. By means of these buttons 9, an operator can transmit instructions or information to the navigation computer 2 and to the cartographic computer 4.

0097Other architectures are possible. For example, the automatic identification systems may be interfaced directly with the navigation computer 2 or with the display device 7.

0098With reference to the <figref idrefs="f0001">Figure 2</figref> And during an elaboration phase, an operator manipulates the buttons 9 to enable the navigation computer to draw up an approach trajectory 25.

0099For example, the operator selects the target platform to be reached from the platforms stored in the database 3, a CRS1 course to follow to reach the target platform, a height variable relative to a minimum decision altitude for a descent in A final approach to said target platform such as a minimum descent altitude (MDA) to be reached for staging after the final descent phase, an offset side to determine where the platform 20 should be in relation to the target, Aircraft to a MAP decision point.

0100The navigation computer then develops an approach trajectory to be followed in order to reach the target platform as a function of the attributes of the platform present in the database 5 and of the parameterized information. This approach trajectory 25 is displayed on the display screen in addition to the information displayed following the instructions of the cartographic computer.

0101The approach trajectory may in particular comprise an initial approach point IAF, a final approach point FAF, an offset point OIP and a decision point MAP as a function of said information and said attributes.

0102Optionally, an intermediate approach point IF and a LPO bearing point are also determined.

0103The initial approach point IAF, the final approach point FAF, the offset point OIP, the coordinates of the target platform and, where appropriate, the intermediate approach point IF and the LPO bearing point are arranged in a Same vertical plane. This vertical plane is directed according to the parameterized CRS1 stroke.

0104On the other hand, the decision point MAP is offset with respect to this vertical plane. It is recalled that the shift to the left or to the right of the decision point with respect to the vertical plane is possibly parametrizable.

0105According to <figref idrefs="f0003">Figure 6</figref>, The decision point MAP, the offset point OIP and, if applicable, the LPO bearing point are arranged at an altitude equal to the minimum decision altitude MDA.

0106However, it is understood that the invention applies to other types of approach trajectories.

0107With reference to the <figref idrefs="f0002">FIG. 4</figref>, The cartographic calculator can then implement a consolidation phase.

0108Thus, the current position 20 "of the platform 20 is determined using, for example, the cartographic calculator 4.

0109For example, this cartographic calculator 4 uses the signals originating from the automatic identification system 5 or from the radar system 6.

0110This step may be carried out at a predetermined location relative to the theoretical position 20 'of the target platform, or on receipt of information providing the current position 20 "such as an AIS signal from the platform 20.

0111Consequently, the distance D1 separating the theoretical position 20 'from the current position 20 "is determined and a visual and / or audible alert is triggered when this distance D1 is greater than a first threshold S1 These steps can be undertaken by the computer The alert being generated for example by the display device 7.

0112If the distance D1 is smaller than the second threshold S2, the manual modification of the platform position 20 is authorized.

0113For example, an operator uses a button 9 to point a geometric locus on the display screen in order to signal to the navigation computer the new position of the platform to be taken into account.

0114According to the method, a vector 45 linking the theoretical position 20 'to the new position 20' is automatically determined. Accordingly, the approach trajectory 25 is automatically shifted by applying the said vector 45 to define a new approach trajectory 25 For example, the cartographic computer transmits the new theoretical position to the navigation computer which calculates the vector to be applied and thus develops the new trajectory.

0115With reference to the <figref idrefs="f0001">Figure 2</figref>, A horizontal representation of the approach trajectory to be monitored is displayed on the display screen. It should be noted that it is also possible to display an alternative approach trajectory 25 'in the course of elaboration. Two distinct trajectories are represented differently to facilitate their visualization.

0116The display screen 8 may also display a vertical representation of the type of the <figref idrefs="f0003">Figure 6</figref>.

0117With reference to the <figref idrefs="f0001">Figure 2</figref>, It can be noted for example that the cartographic calculator may additionally require the display of an approach corridor 50 of a given width 51. The approach corridor 50 is centered on the approach trajectory 25 to be followed. This approach corridor may correspond to the corridor defined by certification regulations

0118The approach corridor may possibly be larger than the dimensions required by the regulations at least locally for safety. For example, the approach corridor may include a straight segment 50 'from the final approach point FAF to the offset point OIP, and then an inclined segment 50' from this OIP shift point, however the right segment 50 ' Can also be extended beyond the OIP offset point.

0119As a complement or as an alternative, a phase is implemented for securing the approach trajectory 25.

0120Accordingly, at a sampling frequency, the current position and the direction of travel and the speed of movement of certain objects on the liquid surface or in the air are determined. More precisely, the cartographic calculator 4 cooperates with the automatic identification system 5 to list the objects 30 provided with an automatic identification system AIS TCAS and present in a predetermined monitoring zone OCZ.

0121The OCZ surveillance zone represented on the <figref idrefs="f0001">Figure 2</figref> Is a circle with a radius R1 centered on the platform 20 to be reached.

0122Consequently, a level of dangerousness of each object is determined with respect to the approach trajectory followed according to rules defined by the manufacturer.

0123Then, on the display screen 8, the horizontal representation of the approach path 25 and for each object is displayed: a plot 41 representing the current position of the object, an indication 42 of the direction of movement of the object , And a representation 43 relating to the level of dangerousness of the object. The indication 42 may be an arrow directed according to the speed vector of the object and having a length depending on the speed of advance of the object. This length may also take into account a given time, the arrow thus being able to indicate the predictive position of the object at the end of this given time.

0124The level of dangerousness can be established by the cartographic calculator which communicates to the display device 7 the data to be displayed and their symbology with possible generation of an audio alert according to the dangerousness.

0125The manufacturer can establish three levels of dangerousness displayed through a coloration of the studs 41. A first level of dangerousness can induce a first type of coloration represented for example by a white color on the stud 31 of the <figref idrefs="f0001">Figure 2</figref>. A second level of dangerousness can induce a second type of coloration represented by one of the hatchings on the pad 32 of the<figref idrefs="f0001">Figure 2</figref>. Finally, a third level of dangerousness can induce a third type of coloration represented by a black color on the pad 33 of the<figref idrefs="f0001">Figure 2</figref>. On an aircraft and by way of example, the second type of coloration may be an amber color, the third type of coloration possibly being a red coloration.

0126Depending on the dangerousness of the objects taken into consideration, it is possible to design an alternative approach trajectory 25 'to avoid objects deemed dangerous. Thus, a change of course can be authorized to pass from an approach path aligned on a first stroke CRS1 to an alternative approach trajectory aligned on a second stroke CRS2.

0127During the security phase, two distinct situations can be distinguished, depending on the position of the aircraft with respect to the final approach point FAF.

0128Before this final approach point FAF is reached, the time TFAF is determined at the end of which the aircraft will reach the final approach point FAF. This step can be undertaken by the cartographic calculator for example. To this end, the cartographic computer can be connected to devices for determining the ground speed of the aircraft.

0129Consequently, the cartographic calculator determines the predictive position of each object studied at the end of this time TFAF. Thus, the aircraft determines where the objects will be when this aircraft reaches the final approach point according to the information transmitted by their automatic identification system.

0130Consequently, the level of dangerousness of each object is established according to its predictive position and its current position with respect to the approach corridor.

0131The cartographic calculator can thus confer on an object the first level of dangerousness when the present position of this object is not located in the approach corridor 50 and when its predictive position will not be located in the approach corridor 50 at Time TFAF. The object marked by the stud 31 thus presents this first level of dangerousness.

0132The second level of dangerousness corresponds to an object having a current position outside the approach corridor 50 but which has a predictive position situated in this approach corridor 50. The object marked by the pad 32 thus has this first level Of dangerousness.

0133Finally, the third level of dangerousness is associated with an object when its present position and its predictive position are located in the approach corridor 50. The block 33 corresponds to the current position of such an object.

0134With reference to the <figref idrefs="f0002">Figure 3</figref>, The system focuses on the objects potentially located in front of the aircraft when the final approach point FAF is reached or exceeded, namely the objects situated between the line 200 and the top of the sheet on which the aircraft is located <figref idrefs="f0002">Figure 3</figref>.

0135Consequently, over time, the present position as well as the direction of travel and the speed of movement of the objects called "intruders" for convenience located either in front of the aircraft 1 or in a circle C1 centered on the aircraft 1 The circle diameter is small and less than the width of an approach corridor.

0136For each intruder and over time, it is determined according to a processing frequency whether the intruder is at a current instant situated in an approach corridor 50 and if this intruder is located in front of the aircraft 1. If the intruder n Is not present in the approach corridor 50 and if said intruder is located in front of the aircraft 1, it is determined whether the intruder will enter said approach corridor 50 in the future and if so when this intruder Will enter the approach corridor 50.

0137These steps can be undertaken by the cartographic calculator.

0138Consequently, an intruder is given the first level of dangerousness represented by a first representation 31 'on the display screen 8 when the intruder is behind the aircraft 1 at a current instant, or when the intruder will be behind Aircraft when entering approach lane 50, or when the intruder will never enter the approach corridor.

0139The intruder, on the other hand, is associated with the second level of dangerousness represented by a second representation 32 'on the display screen 8 when the intruder is in front of the aircraft 1 when it enters the approach corridor 500.

0140Finally, the intruder is associated with a third level of dangerousness represented by a third representation 33 'on the display screen 8 when the intruder is in front of the aircraft 1 in the approach corridor 50 at the current instant.

0141Furthermore, and with reference to <figref idrefs="f0003">FIG. 5</figref>, A movable box 55 can be displayed on request and on the display screen 8. This mobile box corresponds to the horizontal representation to a quadrilateral with a predetermined fixed width 56 and a length 57 equal to the product of a constant Of time CTE and of the ground speed GS of the aircraft 1. The time constant may for example be chosen from a list predetermined by the manufacturer.

0142The moving box 55 is centered transversely on the speed vector of the aircraft and extends longitudinally along this velocity vector from a representation of the aircraft 1. The mobile box thus moves together with the representation of l On the display screen.

0143When this option is enabled, some objects are associated with an additional symbology. More particularly, over time, the current position and the direction of travel, the traveling speed and the predictive location at the end of the said time constant of the objects referred to as the "close-up element" are determined, which are equipped with an automatic system d Which are present in a predetermined scanning zone Z1 centered on the aircraft,

0144For each close-up element, one displays:<ul><li>A first symbology when the current position and the predictive location are not located in the mobile box 55,</li><li>A second symbology when the present position is not located in the mobile box 55 and when the predictive location is located in the mobile box 55,</li><li>A third symbology when the present position is located in the mobile box 55 and when the predictive location is not located in the mobile box 55,</li><li>A fourth symbology when the present position and the predictive location are located in the mobile box 55.</li></ul>

0145Thus, the pad 34 and the associated arrow 34 'remain unchanged according to the first symbology.

0146On the other hand, the arrow 37 'associated with the pad 37 may flash according to the second symbology.

0147In addition, the pad 35 may flash according to the third symbology, the arrow 36 'and the pad 36 both flashing according to the fourth symbology.

0148The frame of the mobile box may also have a particularity when the stud presenting the current position of an object is present in this mobile box. For example, the frame may become red.

0149Naturally, the present invention is subject to numerous variations as to its implementation. Although several embodiments have been described, it is clear that it is not conceivable to identify exhaustively all the possible modes. It is of course possible to replace a means described by an equivalent means without departing from the scope of the present invention.