Abstract:
Embodiments for seamless air traffic control (ATC) data link transfers are disclosed. In at least one embodiment, a method includes receiving a new air traffic control center designation from an original air traffic control center through an active connection. The active connection is based on a first data link standard. The method further includes initiating control transfer by at least one of an aircraft logon to a new air traffic control center or a contact between the original and new traffic control centers. The method additional includes establishing an inactive connection between the new air traffic control center and the aircraft based on a second link standard. The method also includes confirming the establishment of an inactive connection from the aircraft to the new air traffic control center. Additionally, the method includes terminating the active connection between the original air traffic control center and the aircraft.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This patent application is a divisional application of U.S. Pat. No. 7,647,439, issued on Jan. 20, 2010 entitled “Seamless Air Traffic Control (ATC) Datalink Transfers”, which claims priority from U.S. Provisional Application No. 60/741,851 entitled “Seamless ATC Datalink Transfers” filed on Dec. 2, 2005, which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to systems and methods for air traffic control, and more specifically, to systems and methods for communication using a plurality of different air traffic control data link standards. 
     BACKGROUND OF THE INVENTION 
     Air Traffic Control data links presently use two generally incompatible technologies, Future Air Navigation System (FANS), which is used in oceanic and remote airspace, and Aeronautical Telecommunications Network (ATN), which is used in continental Europe and potentially in other congested domestic environments. Typically, an aircraft system is either equipped with the FANS data link technology and associated operator interface, or the ATN data link technology and associated operator interface. 
     Although desirable results have been achieved using such prior art systems, there may be room for improvement. For example, the current ability to implement just a single data link technology on an aircraft means that air traffic control over the aircraft can only be transferred between air traffic control centers that utilize the same data link technology. Therefore, novel systems and methods that allow the utilization of a plurality of different (air traffic control) ATC data link technologies on a single aircraft, as well as novel systems and methods that facilitate the automated transfer of air traffic control over an aircraft between ATC centers that utilize different data link technologies would be highly desirable. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to systems and methods for automatically transferring control from one air traffic control (ATC) center that uses one ATC data link standard to another ATC center that uses a different ATC data link standard. Embodiments of systems and methods in accordance with the present invention may advantageously facilitate the implementation of multiple air traffic control data link technologies on a single aircraft, and may allow greater flexibility in the deployment of aircraft in different geographical regions, in comparison with the prior art. 
     In at least one embodiment, a method for seamless air traffic control (ATC) data link transfers includes receiving a new air traffic control center designation from an original air traffic control center through an active connection. The active connection is based on a first data link standard. The method further includes initiating control transfer by at least one of an aircraft logon to a new air traffic control center or a contact between the original and new traffic control centers. The method additional includes establishing an inactive connection between the new air traffic control center and the aircraft based on a second link standard. The method also includes confirming the establishment of an inactive connection from the aircraft to the new air traffic control center. Additionally, the method includes terminating the active connection between the original air traffic control center and the aircraft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention are described in detail below with reference to the following drawings. 
         FIG. 1  is an isometric view of an aircraft cockpit equipped with a communications system in accordance with an embodiment of the invention; 
         FIG. 2  is a schematic representation of a control transfer from a FANS center to an ATN center, in accordance with an embodiment of the invention. 
         FIG. 3  is a schematic representation of an embodiment of a database system in accordance with an embodiment of the invention; 
         FIG. 4  is a schematic representation of a control transfer from an ATN center to a FANS center, in accordance with an embodiment of the invention; and 
         FIG. 5  is a side elevational view of an aircraft in accordance with another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates to systems and methods for automatically transferring control from one air traffic control (ATC) center that uses one ATC data link standard to another ATC center that uses a different ATC data link standard. Many specific details of certain embodiments of the invention are set forth in the following description and in  FIGS. 1-5  to provide a thorough understanding of such embodiments. The present invention may have additional embodiments, or may be practiced without one or more of the details described below. 
     Generally, embodiments of systems and methods in accordance with the present invention provide systems and methods for automatically transferring control between two ATC centers that use different ATC data link standards. The systems and methods advantageously allow automatic transfers of an aircraft from one ATC center to the next ATC center without flight crew interaction. Furthermore, the mechanisms of the system and methods rely on the ground facility&#39;s uplinks to determine the type of connection to establish. As a result, if a particular control center has FANS as well as ATN data link capabilities, it can determine whether to connect as an ATN or FANS center to the aircraft. Thus, embodiments of the invention advantageously facilitate the implementation of multiple air traffic control data link technologies on a single aircraft, and may allow greater flexibility in the deployment of aircraft in different geographical regions, in comparison with the prior art. 
       FIG. 1  is an isometric view of an aircraft cockpit  100  operatively linked with a system for automatically transferring control between two ATC centers that use different ATC data link standards, in accordance with an embodiment of the invention. The cockpit is also outfitted with a single ATC operator interface communications system. This system works in conjunction with the ATC data link transfers system of the present invention to allow communication via a plurality of data link standards. The single ATC operator communication system is described in U.S. Pat. No. 7,495,602, issued on Feb. 24, 2009, which is incorporated herein by reference. In this embodiment, the aircraft cockpit  100  is equipped with a plurality of keyboards and cursor pointers  102  for data link entry and selection, a plurality of buttons (accept, reject, cancel, etc.)  104  on the glare shield for each crew member, a plurality of automatic uplink displays  106 , and at least one common user interface display  108  for ATC and Aircraft Operational Communication (AOC) data links. 
       FIG. 2  is a schematic representation  200  of a control transfer from a FANS center (transfer air traffic services unit, a.k.a. transfer ATSU)  202  to an ATN center (transfer ATSU)  204 , in accordance with an embodiment of the invention. As illustrated in  FIG. 2 , FANS Controller/Pilot Data Link Communication (CPDLC) messages are represented by solid lines, e.g., step  206 . Air Traffic Services (ATS) Facilities Notification (AFN) messages are represented by dotted lines, e.g., step  210 . Context Management (CM) messages are represented by short dash lines, e.g., step  212 . Lastly, ATN CPDLC messages are represented by long dash lines, e.g., step  218 . 
     The process initiates at step  208 , when the FANS center  202  sends a FANS CPDLC “NEXT DATA AUTHORITY” message (uplink message  160 ) to an aircraft, where it is received by avionics  206 . The next control center designated by this message (in this case ATN center  204 ) is treated by both FANS and ATN CPDLC applications of the aircraft avionics  206  as a next data authority. It will be appreciated that because of the limitations of the FANS Facility Designation parameter, the designation of an ATN center, such as ATN center  204 , can only occur if the center has a 4-character ICAO identifier (whereas ATN allows 4-8 characters). Thus, step  208  is limited to transfers to ATN centers having a 4-character ICAO identifier. Next, the FANS center  202  also sends an AFN Contact Advisory Message to the aircraft at step  210 , and the airplane avionics  206  responds with an AFN response at step  212 . Normally, the address in the AFN Contact Advisory Message sent at step  210  is the 7-character Aircraft Communication Addressing and Reporting System (ACARS) address of the facility. For this purpose, the 3 characters “ATN” are appends to the 4-character ICAO identifier, indicating that the next center is an ATN center. 
     Meanwhile, the aircraft avionics  206  then determines from at least one of the “NEXT DATA AUTHORITY” message or the AFN contact advisory message that the next air traffic control center is an ATN center, in this case, ATN  204 . Next, the aircraft avionics  206  sends a Context Management Logon Request to the ATN center  204  at step  214 , using the address of the ATN center  204  from an on-board database. At step  216 , The ATN center  204  responds to the aircraft with a Context Management Logon Response. On receipt of the Context Management logon response, and with the knowledge that it is responding to a logon request issued as a result of an AFN Contact Advisory, the aircraft avionics  206  sends the AFN Complete message to the FANS center at step  218 . The process then continues to step  220 , at which point the ATN center  204  initiates a CPDLC Start Request to the aircraft, upon which the aircraft avionics  206  responds with a Start Confirm at step  222 . At this point, the FANS application has an active CPDLC connection, and the ATN application has an inactive (next center) connection. It will be appreciated that at this point, the receipt of another “Next Data Authority” message by the aircraft avionics  206  will terminate the inactive connection between the aircraft and the ATN center  204 , just as it does in an ATN center to ATN center transfer, or a FANS center to FANS center transfer. 
     However, if the transfer process continues from step  222 , FANS center  2042  will send an End Service message at step  224 . This message terminates the existing FANS connection (resulting in the Disconnect Request to the FANS center  202 ) at step  226 , and turns the inactive connection with the ATN center, established using steps  220  and  222 , into an active one. It will be appreciate that this embodiment encompasses a simple transfer. In other embodiments, a message that requires a WILCO response may be included as part of the transfer process, and the termination of the existing FANS connection and the transfer of the connection to the next ATN center only occurs when the WILCO is sent. Once steps  222  and  224  are complete, the aircraft avionics  206  sends a Current Data Authority message to the ATN center at step  228  indicating it has an active connection, and the ATN center responds with a Logical Acknowledgement (LACK) at step  230 , in the same fashion as during an ATN center to ATN center control transfer. 
     It will be appreciated that in another embodiment of the FANS center to ATN center control transfer process, steps  208  and  210  may be reversed from the aircraft perspective. In this embodiment, the only requirement from the perspective of the aircraft is that step  208  must be completed prior to step  216 . In another embodiment, steps  210 ,  212 ,  214 ,  216 , and  218  may be replaced by a ground-to-ground Contact Management Contact Process, without involvement of the aircraft avionics  206 . In other words, if the FANS center  202  chooses to do so, FANS center  202  may substitute steps  210 ,  212 ,  214 ,  216 , and  218  with a direct Context Management Contact process to indicate to the ATN center  204  that it may start the control transfer process and initiate step  220 . 
     In yet another embodiment of the FANS center to ATN center control transfer process, the ATN center  404  may initiate a FANS Automatic Dependent Surveillance (ADS) connection to an aircraft at any time during the process. For example, the FANS ADS connection may be initiated to obtain the NEXT and NEXT+1 waypoints. To achieve this, the ATN center needs the aircraft registration (from the filed flight plan) and the aircraft type to determine which set of standard message identifiers (SMIs) to use. The SMIs differ depending on whether a particular aircraft model has the Air Traffic Services (ATS) function hosted in the Communications Management Unit (CMU) or elsewhere, such as the Flight Management Computer (FMC). An ATN center may obtain this information (aircraft registration and SMI) from a database it maintains, from the aircraft model in the filed flight plan, or from the center that initiated the control transfer. Currently proposed modifications to the Aeronautical Interfacility Data Communication (AIDC) message set would also provide this information. Lastly, in a final embodiment of the control center transfer process, a connection request received by the FANS CPDLC application of the aircraft from a valid NEXT DATA AUTHORITY establishes an inactive next center connection, regardless of whether the FANS CPDLC application has an active connection to another center. 
       FIG. 3  is a schematic representation of an embodiment of a database system  300  that may be used to determine whether a center is a FANS center or ATN center. It may also be used to determine the addressing information of a particular ATN air traffic control center. As depicted in  FIG. 3 , the database system  300  includes a database management component  304 . An initial database  302  is loaded into the system and coupled to the database management component  304 . The data in database  302  may typically be stored in non-volatile memory (NVM)  306 . An ATS applications component  308  uses the data stored in NVM  306  to obtain addressing information. A minor change to the AFN protocols to allow use of 4-character ATC center identifier, rather than a 7-character ACARS address, is necessary for the implementation of the database system  300 . In addition, the ground system must also use appropriate default values for ATN addresses when a Context Management message specifies a FANS center. 
     In some embodiments, the database  302  and NVM  306  may be updated by information contained in Context Management (CMA) contact messages received by the database management component  304 . The database  302  and NVM  306  may also be updated by blind contact messages, that is, contact message received without having the aircraft equipped initiated a Context Management logon to an air traffic services unit (ATSU). Reloading the database  302  or the data link application software would delete any updated information, and the airplane would start with the data in the loaded database  302 . 
       FIG. 4  is a schematic representation  400  of a transfer from an ATN center (transfer ATSU)  402  to a FANS center (transfer ATSU)  404 , in accordance with an embodiment of the invention. As illustrated in  FIG. 4 , FANS CPDLC messages are represented by solid lines, e.g., step  420 . AFN messages are represented by dotted lines, e.g., step  414 . Context Management messages are represented by short dash lines, e.g., step  412 . Lastly, ATN CPDLC messages are represented by long dash lines, e.g., step  424 . 
     The process initiates at step  408 , when the ATN center  402  sends an ATN CPDLC “NEXT DATA AUTHORITY” message (uplink message  160 ) to an aircraft, where it is received by aircraft avionics  406 . The next control center designated by this message (in this case FANS center  404 ) is treated by both the FANS and ATN CPDLC applications of the aircraft avionics  406  as a next data authority. It will be appreciated that if the next control center has an ICAO identifier longer than 4 characters, the aircraft avionics  406  will identify the next control center as an ATN center. This is due to the fact that FANS center identifiers are limited 4 characters. In response to the message of step  408 , the aircraft avionics  406  responds with a Logical Acknowledgement (if not prohibited) at step  410 . 
     Next, at step  412 , the ATN center  402  sends a CM Contact Request message to the aircraft. The address in the uplink will be all zeros, and the facility identifier will contain the 7-character ACARS address of the next control center. Once the aircraft avionics  406  determines (from the all-zero address) that the identified center is a FANS center, in this case FANS center  404 , the aircraft avionics  406  sends an AFN Contact message to the FANS center  404  using the 7-character facility identifier in the message at step  414 . In turn, the FANS center  404  responds with an AFN Acknowledgement at step  416 . Further, once the aircraft receives the AFN acknowledgement, and with the knowledge that it is responding to an AFN Contact message issued as a result of a CM Contact Request message, the aircraft avionics  406  sends the Contact Response message to the initiating ATN center  402  at step  418 . 
     The process continues when the FANS ground center sends a CPDLC Connect Request (CR 1 ) to the aircraft avionics  406  at step  420 . In response to the connection request, the aircraft responds with a Connect Confirm (CC 1 ), in the same fashion as it would acknowledge any other FANS connection request, at step  422 . At this point, the ATN application has an active CPDLC connection, and the FANS application has an inactive (next center) connection. It will be appreciate that at this point, the receipt of another NEXT DATA AUTHORITY message will terminate the inactive connection. 
     However, if the transfer process continues from step  422 , the ATN center  402  sends a CPDLC End Request message at step  424 . This terminates the existing ATN connection (resulting in the Confirm End message to the ATN center at step  426 ), and turns the inactive connection with the FANS center, established at step  420 , into an active one. Once step  424  is complete, the aircraft reacts just as in a transfer from a FANS center to the next FANS center. Both the aircraft avionics  406  and the FANS center  404  may now initiate CPDLC messages, as shown in step  428 . It will be further appreciated that the usual procedure in FANS airspace is to send a position report on crossing an FIR boundary, to indicate that communication with the new center has been established. 
     In another embodiment of the invention, steps  408  and  412  may be reversed from the aircraft perspective. The only requirement from the perspective of the aircraft is that Step  408  must be completed prior to Step  420 . In another embodiment, Steps  412 ,  414 ,  416 , and  418  may be replaced by a ground-to-ground AFN contact advisory transaction, without involvement of the aircraft avionics  406 . In other words, if the ATN center  402  chooses to do so, ATN center  402  may substitute steps  412 ,  414 ,  416 , and  418  with a direct AFN contact advisory transaction to indicate to the FANS center  404  that it may start the control transfer process and initiate step  420 . 
     It will be appreciated that when an aircraft transfers from one control center to another, open uplink and downlinks, that is, those having a response enabled per the defining standards, (i.e., ROGER, WILCO/UNABLE, or AFFIRMATIVE/NEGATIVE) are automatically aborted. As a result, there are no issues for a FANS-1/A to ATN control transfer, or vice versa, with respect to these links. Nevertheless, there are other situations where an uplink request can result in a report being transmitted. If this has not occurred before the control transfer, existing systems (i.e., FANS to FANS or ATN to ATN) will transmit the report (if sent manually by the crew or automatically by having been armed) to the new center. However, with respect to a FANS-1/A to ATN control transfer, or vice versa, the differing data link standards can potentially result in an automatically transmitted report that is not defined for a new center&#39;s message set or a report that is subtly different. Therefore, for a FANS-1/A to ATN transfer, or vice versa, “open” reports should be aborted. Lastly, in a final embodiment of the control center transfer process, a connection request received by the ATN CPDLC application of the aircraft from a valid NEXT DATA AUTHORITY establishes an inactive next center connection, regardless of whether the ATN CPDLC application has an active connection to another center. 
     Embodiments of the present invention may be used in a wide variety of aircrafts. For example,  FIG. 5  is a side elevational view of an aircraft  500  in accordance with an embodiment of the present invention. In general, except for one or more systems in accordance with the present invention, the various components and subsystems of the aircraft  500  may be of known construction and, for the sake of brevity, will not be described in detail herein. As shown in  FIG. 5 , the aircraft  500  includes one or more propulsion units  504  coupled to a fuselage  502 , a cockpit  512  in the fuselage  502 , wing assemblies  506  (or other lifting surfaces), a tail assembly  508 , a landing assembly  510 , a control system (not visible), and a host of other systems and subsystems that enable proper operation of the aircraft  500 . At least one ATC data link transfer system  514  formed in accordance with the present invention is located within the fuselage  502 . However, additional ATC data link transfer system  514  and components thereof may be distributed throughout the various portions of the aircraft  500 . 
     Although the aircraft  500  shown in  FIG. 5  is generally representative of a commercial passenger aircraft, including, for example, the 737, 747, 757, 767, 777, and 787 models commercially-available from The Boeing Company of Chicago, Ill., the inventive apparatus and methods disclosed herein may also be employed in the assembly of virtually any other types of aircraft. More specifically, the teachings of the present invention may be applied to the manufacture and assembly of other passenger aircraft, cargo aircraft, rotary aircraft, and any other types of aircraft, including those described, for example, in The Illustrated Encyclopedia of Military Aircraft by Enzo Angelucci, published by Book Sales Publishers, September 2001, and in Jane&#39;s All the World&#39;s Aircraft published by Jane&#39;s Information Group of Coulsdon, Surrey, United Kingdom, which texts are incorporated herein by reference. It may also be appreciated that alternate embodiments of system and methods in accordance with the present invention may be utilized in other manned aerial vehicles. 
     Embodiments of systems and methods in accordance with the present invention may provide significant advantages over the prior art. For example, because the data link transfer system allows automatic transfers of an aircraft from one ATC center to the next ATC center without flight crew interaction, it facilitates the implementation of multiple air traffic control data link technologies on a single aircraft. More significantly, the data link transfer system advantageously allows greater flexibility in the deployment of aircrafts to airspace in different geographical regions. 
     While embodiments of the invention have been illustrated and described above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of these embodiments. Instead, the invention should be determined entirely by reference to the claims that follow.