Abstract:
Systems and methods for automatically switching to a track view mode on a vertical view display. The system determines aircraft position relative to a leg of a flight plan and switches display mode for a navigation vertical display to track view mode, if the display mode is in a plan view mode and if the determined relative position is greater than a threshold distance.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Many aircraft include a number of navigation displays, particularly, a plan view display and a vertical view display. The plan view display is a top-down view of a navigation map that may display various information, such as terrain data, weather data, traffic data and navigation data. The vertical view display illustrates a side view of either where the aircraft is currently headed or what is expected along the flight plan of the aircraft.  
         [0002]     On a typical flight the air crew selects the mode of the vertical view display in order to get an overall picture of what they will be seeing on the next leg or legs of their flight plan. However, if the aircraft is deviating from their flight plan, the information displayed on the vertical view display may not present obstacles that are along the aircraft&#39;s current track. If the air crew is attentive, they will switch to the track view mode of the vertical view display in such situation. However, this may not always occur. Therefore, there exists a need for a switching device that automatically switches from the flight plan vertical view mode to the track view mode of the vertical view display.  
         [0003]     One attempt to resolve this issue has been to perform an automatic switch based solely on angular deviation between the angular track of the aircraft and the direction of the leg of the flight plan. However, unnecessary automatic switches may occur when the deviation is greater than the threshold limit, but the aircraft is on or very close to their present track.  
         [0004]     Therefore, there exists a need for methods and systems for more intelligently switching from flight plan view mode of the vertical view display to the track view mode. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]     The preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings.  
         [0006]      FIG. 1  illustrates a block diagram of an exemplary system formed in accordance with an embodiment of the present invention;  
         [0007]      FIGS. 2 and 5  illustrate methods performed by the system shown in  FIG. 1 ;  
         [0008]      FIGS. 3 and 4  illustrate geometrical relationships used by the processes shown in the flow diagrams of  FIGS. 2 and 5 ;  
         [0009]      FIG. 5  illustrates a flow diagram illustrating a detailed exemplary process performed by the system shown in  FIG. 1 . 
     
    
     DETAILED DESCRIPTION  
       [0010]      FIG. 1  illustrates a block diagram of an example system  18  on board an aircraft  20 . The system  18  illustrates an embodiment of the present invention. The example system  18  includes a processing device  26 , such as a Flight Management System (FMS), coupled to one or more sensors  28  and a display device  30 . The display device  30  includes at least a vertical view display  38 . The display device  30  may also include a plan view display  36 .  
         [0011]     The processing device  26  receives various data, such as position and track data from the sensors  28 . The sensors  28  may include a Global Positioning System (GPS), an inertial reference system (IRS), or other position determining devices. The device  26  may also be linked to memory  40  that stores flight data information, such as an aircraft flight plan that includes course and geometry information for legs of the flight plan. The device  26  processes the information stored in the memory  40  and the information from the sensors  28  to generate images to be displayed on either the plan view display  36  and/or the vertical view display  38 . The device  26  may also be in communication with an alerting device  42  that alerts the flight crew that a switch of the image presented in the vertical view display  38  has occurred. The alerting device  42  may be a visual or audio alerting device (e.g., icon, light, speaker, etc.), or may be integrated into the displays  36  and  38 , or into other pre-existing equipment used within a cockpit of the aircraft  20 .  
         [0012]      FIG. 2  illustrates an example process  80  performed by the system shown in  FIG. 1 . First at a block  82 , the device  26  determines cross-track distance. The cross-track distance is the distance between the position of the aircraft  20  and a leg of the flight plan that the aircraft  20  is presently on. As shown in  FIG. 3 , the distance  100  is the cross-track distance and that distance is the perpendicular distance between the aircraft&#39;s position and the intended path of the flight plan leg. Next, at a block  86 , the device  26  determines a swath width. Referring to  FIG. 3 , the swath width is a distance  110  between the intended path  104  and a swath width boundary  112 . The swath width  110  may vary depending upon one or more different factors, for example, stage of flight (cruise, ascent, descent, etc.), type of aircraft, or any other pre-determined factor.  
         [0013]     Next, at a decision block  88 , the device  26  determines if the determined cross-track distance  100  is greater than the swath width distance  110 . If the cross-track distance is determined to be greater than the swath width distance  110 , the device  26  switches the vertical view display  38  into a track view mode if the vertical view display was previously in a flight plan view mode. If the cross-track distance is not greater than the swath width distance  110 , the device  26  determines a down-track width distance.  FIG. 3  illustrates an example down-track width distance  120 . The down-track width distance  120  is determined by projecting a vector from the aircraft&#39;s present position based on the aircraft&#39;s present ground speed and track. The perpendicular distance between the intended path  104  and a point at the end of the projected vector is the down-track width distance  120 .  
         [0014]     Next, at a decision block  98 , the device  26  determines if the aircraft is diverging from the intended path  104  and the down-track width distance  120  is greater than the swath width distance  110 . If the answer to the determination made at decision block  98  is no, then the process  80  is delayed a pre-determined set amount of time and then returned to the block  82 . If the result of the decision at the decision block  98  is yes, the device  26  switches to the track view mode if previously in the flight plan view mode.  
         [0015]     As shown in  FIG. 4 , example converging and diverging situations are illustrated. In a pair of scenarios shown in block  160 , an aircraft to the left of the intended path  104  is converging into the intended path  104  and an aircraft to the right of the intended path  104  is diverging from the intended path  104 . A block  164  illustrates an aircraft to the left of the intended path  104  is diverging from the intended path  104  and an aircraft to the right of the intended path  104  is converging with the intended path  104 . Thus, two diverging situations may occur out of a possible four flight situations.  
         [0016]     In another embodiment, after or simultaneously when the switch to the track view mode has occurred (block  90 ), an alert signal is sent to the alerting device  42  thereby alerting the flight crew that a switch of the modes of the vertical view display  38  has occurred.  
         [0017]      FIG. 5  shows a more detailed process that performs the same function as the process  80  shown in  FIG. 2 . A cross-track distance XTD is determined based on current latitude/longitude position of the aircraft and the current leg of the flight plan. If the XTD is greater than the current swath width W, then track view mode is used.  
         [0018]     The true course of the current leg is subtracted from the current true track of the aircraft. If the true track is greater than the true course, a high (“1”) signal is produced. If the true track is less than the true course, a low (“0”) signal is produced. If the aircraft is to the left of the flight plan, a high (“1”) signal is produced and a low (“0”) signal is produced if the aircraft is to the right of the flight plan. Divergence between the true course and the flight plan is determined by exclusive or-ing the signals. If divergence is occurring and a downtrack distance is greater than W, then the track view mode is used.  
         [0019]     While the preferred embodiment of the invention has been illustrated and described, as noted 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 the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.