Abstract:
Systems and methods for managing a visual display in a ground proximity warning system. In one embodiment, a system includes at least one aircraft sensor system operable to acquire aircraft data and a ground proximity warning computer coupled to the aircraft sensor system that is operable to process the aircraft data to generate ground proximity warning data corresponding to a sensed ground obstruction. An indicating system includes at least one visual display device that is operable to display terrain elevations and to display a visual symbol corresponding to at least one of the ground obstructions, wherein at least one of the computer and the visual display device is controllable to selectively alter an appearance of the visual symbol relative to the terrain elevations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims benefit of U.S. Provisional Application Ser. No. 60/674,223, filed Apr. 21, 2005, which is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   Ground proximity warning systems (GPWS) are known and are presently installed on a wide variety of aircraft. Such systems generally provide both aural and visual warnings of inadvertent aircraft descent during flight operations. For example, a GPWS may be configured to detect an excessive loss of altitude during a landing procedure, following a take-off, or during a go-around following a missed landing approach. The GPWS also advantageously provides aural and visual warnings of potential terrain collisions during controlled flight over relatively high altitude terrain. In general, the GPWS detects an altitude loss by computing a barometric altitude (MSL), a geometric altitude, and/or a descent rate based upon changes in the barometric pressure. In cases where the terrain underlying the aircraft is rising relative to the aircraft, a radio altitude is computed in order to determine an altitude above ground level (AGL). 
   Although present ground proximity warning systems significantly enhance the safety of flight, other potentially hazardous terrain or man-made obstructions nevertheless exist. For example, radio transmission towers, smokestacks and other similar structures abruptly project outwardly from the terrain. Obstructions of the foregoing type are generally depicted in various aeronautical publications (including, for example, the well-known terminal area chart (TAC), sectional aeronautical chart (SAC) and world aeronautical chart (WAC)) and may also be represented in a variety of commonly available navigational databases that may be accessed by the ground proximity warning system so that a symbolic representation of obstacle may be displayed on a terrain awareness display (TAD) located within the aircraft. 
   Although the display of ground obstacles on a TAD constitutes a significant contribution to flight safety, various potential drawbacks may nevertheless exist. For example, the symbol associated with the ground obstacle may not be readily distinguishable from a terrain depiction on the TAD, so that a flight crew may fail to properly observe the obstacle on the TAD. In a further example, a color associated with a terrain depiction of a selected geographical location may not permit a color-coded ground obstruction symbol to be properly distinguished. 
   What is needed in the art is a system and method for managing a visual display so that ground obstructions may be effectively recognized by the flight crew. 
   BRIEF SUMMARY OF THE INVENTION 
   Systems and methods for managing a visual display in a ground proximity warning system are disclosed. In one aspect, a system includes at least one aircraft sensor system operable to acquire aircraft data and a ground proximity warning computer coupled to the aircraft sensor system that is operable to process the aircraft data to generate ground proximity warning data corresponding to a sensed ground obstruction. An indicating system includes at least one visual display device that is operable to display terrain elevations and to display a visual symbol corresponding to at least one of the ground obstructions, wherein at least one of the computer and the visual display device is controllable to selectively alter an appearance of the visual symbol relative to the terrain elevations. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. 
       FIG. 1  is a block diagrammatic view of a ground proximity warning system according to an embodiment of the invention; 
       FIG. 2  is a ground obstacle depiction that illustrates a method of display management according to another embodiment of the invention; 
       FIG. 3  is an enlarged, partial view of the viewing surface that is used to describe the ground obstruction symbol of  FIG. 2  in greater detail; and 
       FIG. 4  is an enlarged, partial view of the viewing surface of  FIG. 2  that is used to describe a ground obstruction symbol in accordance with another embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention relates to ground proximity warning systems and methods. Many specific details of certain embodiments of the invention are set forth in the following description and in  FIGS. 1 through 4  to provide a thorough understanding of such embodiments. One skilled in the art, however, will understand that the present invention may have additional embodiments, or that the present invention may be practiced without several of the details described in the following description. In the discussion that follows, it is understood that “color” describes a property of visible electromagnetic radiation that may be described in terms of dominant wavelength, luminance, and purity. Accordingly, visible electromagnetic radiation having a red color property corresponds to a range of wavelengths between approximately about 630 to 760 nanometers (nm), while visible radiation having a green color property corresponds to a range of wavelengths between approximately about 490 to 570 nm. A blue color property corresponds to a range of wavelengths between approximately about 420 to 490 nm, and a yellow color property corresponds to a range of wavelengths between approximately about 565 to 590 nm. 
     FIG. 1  is a block diagrammatic view of a ground proximity warning system  10  according to an embodiment of the invention. The system  10  includes a ground proximity-warning system (GPWS) computer  12  (or an enhanced GPWS (EGPWS)) that is coupled to a plurality of aircraft sensors  14  and associated systems, including, for example, pitot-static sensors, a global positioning system (GPS), and an air data system. The system  10  is also coupled to one or more indicating systems  16 , which are operable to convey audio and/or visual warnings to a flight crewmember. Accordingly, the one or more indicating systems  16  may include a flight deck speaker and interphone system  18 , an alert lamp and electronic flight instrument system (EFIS) indicating system  20 , and an EFIS navigational display and weather radar display system  22 . The indicating systems  16  may also be coupled to various devices that permit a flight crewmember to communicate with the system  10 . For example, the various devices may include a keyboard, a pointing device, including a “mouse” or a trackball, or other similar devices operable to transfer commands to the system  10 . 
   The GPWS computer  12  includes one or more processors that are configured to perform a variety of functions. For example, the computer  12  may include a GPWS processor  24  that is operable to execute various algorithms to detect a ground (or obstacle) proximity event, and also includes algorithms configured to manage the display of obstacles on a selected display device, as will be described in greater detail below in connection with other embodiments of the invention. An aural callout processor  26  operable to generate audio warnings associated with ground (or obstacle) proximity events may also be present. A terrain awareness and obstacle alerting processor  28  is also present in the GPWS computer  12 . The processor  28  is operable to process information from the systems  14  and to execute algorithms to obtain terrain obstacles so that appropriate warnings based upon the terrain obstacles may be obtained. A terrain clearance floor processor  30  may also be present in the GPWS computer  12 . The processor  30  processes terrain floor algorithms to generate terrain floor information. A windshear detection and alerting processor  32  processes windshear algorithms and similarly generates windshear information for display. The computer  12  also includes an input processing module  34  that processes the signals obtained from the aircraft sensors and systems  14  to appropriately format the signals prior to transferring the signals to the GPWS processor  24 , the aural callout processor  26 , the terrain awareness and obstacle alerting processor  28 , the terrain clearance floor processor  30 , and the windshear detection and alerting processor  32 . An output processing module  36  receives processed signals from the GPWS processor  24 , the aural callout processor  26 , the terrain awareness and obstacle alerting processor  28 , the terrain clearance floor processor  30 , and the windshear detection and alerting processor  32  and appropriately formats the processed signals before transferring the signals to the flight deck speaker and interphone system  18 , the alert lamp and electronic flight instrument system (EFIS) indicating system  20 , and/or the EFIS navigational display and weather radar display system  22 . 
     FIG. 2  is a ground obstacle depiction  40  that will be used to describe a method of display management according to another embodiment of the invention. The ground obstacle depiction  40  may be presented to a viewer, such as a flight crewmember, on a viewing surface  42  of a terrain awareness display (TAD)  44  positioned within an aircraft cockpit. The TAD  44  may be the foregoing EFIS navigational display and weather radar display system  22  of  FIG. 1 , or other similar display devices. The TAD  44  is generally configured to display a symbolic representation  46  of the aircraft, and a viewing sector  48  that extends radially outwardly from the symbolic representation  46  of the aircraft. The TAD  44  is also configured to display terrain obstructions, aircraft traffic, navigational information and/or weather obstructions within a predetermined range and bearing relative to the aircraft. Accordingly, the viewing sector  48  also typically includes a directional bearing  50  of the aircraft. In general, the range R of the viewing sector  48  is selectable and alterable by a flight crew member to provide a desired resolution on the viewing surface  42  of the TAD  44 . 
   The sector  48  also includes a graphical representation of terrain contours  52  that depict different terrain elevations in proximity to the aircraft. In the viewing sector  48  of  FIG. 2 , a first terrain contour  52  encloses a first terrain region  54 , while a second terrain contour  56  and the first terrain contour  52  enclose a second terrain region  58 . A third terrain contour  60  further encloses a third terrain region  62 . The first terrain region  54 , the second terrain region  58  and the third terrain region  62  are generally depicted on the viewing surface  42  using different colors that correspond to elevation differences. For example, a terrain elevation that is more than two-thousand feet below an aircraft altitude typically appears as a black area on the display surface  42 , while a terrain elevation that is between approximately two-thousand feet below the aircraft altitude and up to the aircraft altitude is shown as a green area on the display surface  42 . Terrain having an elevation that is above the aircraft altitude is shown as a yellow area if the terrain is between the aircraft altitude and extending up to approximately two thousand feet above the aircraft altitude. If a terrain elevation is more than about two thousand feet above the altitude of the aircraft, it is typically shown as a red area on the display surface  42 . The terrain colors may also be dependent upon a threat level of the terrain as determined by the GPWS processor  24 . 
   Still referring to  FIG. 2 , the viewing sector  48  may also include at least one ground obstruction symbol  64  that represents a ground obstacle such as a radio transmission antenna or a smokestack, or other similar ground-based obstructions. Although a triangular-shaped ground obstruction symbol  64  is shown, other symbol configurations are possible. For example, the ground obstruction symbol  64  may conform generally to ICAO standards for ground obstruction symbology so that the symbol has a predetermined shape based upon a height of the obstacle above the underlying terrain and/or based upon whether the obstacle is one of a ground obstruction, such as a radio antenna farm or an industrial installation having a plurality of towers or smokestacks, or other similar collections of obstructions. 
   In one embodiment, the ground obstruction symbol  64  includes an interior portion  66  and an outer peripheral portion  68  that substantially surrounds the interior portion  66 . The interior portion  66  is depicted on the viewing surface  42  using different colors that generally correspond to a detected alert status for the associated ground obstruction. For example, a color of the interior portion  66  may be red as it is displayed on the viewing surface  44  if a “warning” alert level is detected. Alternately, the color of the interior portion  66  may be yellow as it is displayed on the viewing surface  44  if a “caution” alert level is detected. Accordingly, the interior portion  66  of the ground obstruction symbol  64  may not be readily distinguishable from the terrain regions  54 ,  58  and  62  because a color of the interior portion  66  and the color of the terrain regions  54 ,  58  and  62  are substantially similar. 
     FIG. 3  is an enlarged, partial view of the viewing surface  42  that will be used to describe the ground obstruction symbol  64  of  FIG. 2  in greater detail. As noted earlier, the ground obstruction symbol  64  includes an interior portion  66  that may be depicted on the viewing surface  42  using a selected color that corresponds to a detected alert level. Since the selected color may not be properly distinguishable from a color of a terrain region that surrounds the ground obstruction symbol  64 , a color of the outer peripheral portion  68  may be selected to provide a suitable visual contrast between the interior portion  66  and the color of the terrain region. For example, in one particular embodiment, the color of the outer peripheral portion  68  may be black when depicted on the viewing surface  42 . Alternately, and in another particular embodiment, the peripheral portion  68  may be depicted using a color, texture or intensity that is complementary to a color of the interior portion  66 . For example, when the interior portion  66  is depicted on the viewing surface  42  using a red color, the peripheral portion  68  may use a white or other color. If the interior portion  66  is depicted on the viewing surface  42  using a yellow color, one of white, or another color may be used, in order to provide a desired visual contrast. 
     FIG. 4  is an enlarged, partial view of the viewing surface  42  of  FIG. 2  that will be used to describe a ground obstruction symbol  70  in accordance with another embodiment of the invention. The ground obstruction symbol  70  includes the interior portion  66 , as described in detail in connection with other embodiments, an intermediate portion  72  that substantially surrounds the interior portion  66 , and an outer peripheral portion  74  that encloses the intermediate portion  72 . The intermediate portion  72  is selectively displayed using a color that provides a desired visual contrast between the interior portion  66  and the intermediate portion  72 . Additionally, the intermediate portion  72  and/or the outer peripheral portion  74  may be intermittently displayed, so that the intermediate portion  72  and/or the outer peripheral portion  74  is periodically presented on the viewing surface  42  according to a predetermined period so that attention is drawn to the ground obstruction symbol  70 . Alternatively, the shape, color or intensity of the interior portion  66  may be altered to draw attention to the ground obstruction symbol  70 . 
   Although the interior portion  66  of  FIG. 3  and  FIG. 4  displayed on the display surface  42  is illustrated as having a generally triangular shape, it is understood that other regular polygonal shapes may also be used. For example, the interior portion  66  may be a rectangular, circular or elliptical shape. Also, the shape may include means to convey more precisely the obstacle location within surface  66 , e.g., a “filled dot”. 
   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. Also, the steps in the process  100  may be performed in various order. 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.