Abstract:
A method of providing weather radar images to a flight crew of an aircraft includes obtaining raw volumetric radar data corresponding to at least one signal reflected off of a weather system. Based on the radar data, the weather system is computationally classified as being of a first type of a plurality of weather-system types. After classifying the weather system, the radar data is image processed, the image processing yielding an image representing the weather system and corresponding to the first weather-system type. The image is displayed on a display device.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Weather has been identified as a cause or contributing factor to many aviation accidents and fatalities. Accidents can occur when a chain of events leads to a failure of an aircraft system, a mistake on part of the crew piloting the aircraft, or a combination thereof. Improved levels of weather information and the use of pilot decision aids may be helpful in breaking the chain of events that leads to an accident. 
         [0002]    It is known that when using conventional weather radar systems, both the shape of storm cells and reflectivity levels are indicators of significant weather threats. Pilot training normally includes familiarization of characteristic weather cell shapes displayed in two-dimensions that may imply significant weather threats. Examples include (some of which are illustrated in  FIG. 1 ):
       U-shapes;   thin protruding fingers;   scalloped edges;   hooks;   V-notch;   pendant;   steep rain gradients;   line echo wave pattern; and   bow shaped line of echoes.       
 
         [0012]    These cells are generally associated with conditions such as unstable air masses, hail and tornadoes and should be avoided. 
         [0013]    Flight crews are currently required to visually detect these types of weather threats, an exercise that can be extremely challenging given the workload of the flight crew during flight, particularly during terminal area operations. 
       SUMMARY OF THE INVENTION 
       [0014]    In an embodiment, a method of providing weather radar images to a flight crew of an aircraft includes obtaining raw volumetric radar data corresponding to at least one signal reflected off of a weather system. Based on the radar data, the weather system is computationally classified as being of a first type of a plurality of weather-system types. After classifying the weather system, the radar data is image processed, the image processing yielding an image representing the weather system and corresponding to the first weather-system type. The image is displayed on a display device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. 
           [0016]      FIG. 1  illustrates display characteristics of known hazardous weather conditions; 
           [0017]      FIG. 2  illustrates an exemplary system formed in accordance with an embodiment of the present invention; and 
           [0018]      FIGS. 3-7  illustrate alternative-embodiment plan views of reflectivity of storm cells sensed by a radar system according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0019]    Embodiments of the invention employ processing of 3-D radar reflectivity data and data-pattern recognition techniques to detect and identify hazardous weather conditions on the basis of volumetric radar data. Previous approaches, such as that described in U.S. Pat. No. 6,650,275, have focused on processing of radar image data in two dimensions. In an embodiment, reflected data is not image processed prior to classifying the nature and/or severity of a weather system. 
         [0020]      FIG. 2  illustrates an example of a suitable operating environment in which the invention may be implemented. The operating environment is only one example of a suitable operating environment and is not intended to suggest any limitation as to the scope of use or functionality of the invention. The operating environment may include or be a component of a three-dimensional buffer processing system, such as the RDR-4000 weather radar system manufactured by Honeywell®, including its volumetric buffer technology. Other well known computing systems, environments, and/or configurations that may be suitable for use with the invention include, but are not limited to, personal computers, server computers, hand-held or laptop devices, multiprocessor systems, microprocessor-based systems, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like. 
         [0021]    The invention may be described in the general context of computer-executable instructions, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments. 
         [0022]    The operating environment illustrated in  FIG. 2  typically includes at least some form of computer readable media. Computer readable media can be any available media that can be accessed by one or more components of such operating environment. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by one or more components of such operating environment. Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Combinations of the any of the above should also be included within the scope of computer readable media. 
         [0023]    Embodiments of the invention include a system, method, and computer program product for alerting a pilot of hazardous weather conditions at high altitude.  FIG. 2  illustrates an exemplary system  30  formed in accordance with an embodiment of the present invention. The system  30  includes a weather radar system  40 , a display processor  42 , memory  43 , a display device  44 , an air data computer  46 , and user interface  48  coupled to the display processor  42 . The display processor  42  is electrically coupled to the radar system  40 , the display device  44 , the air data computer  46 , and the memory  43 . 
         [0024]    An embodiment of the radar system  40  includes a radar controller  50 , a transmitter  52 , a receiver  54 , and an antenna  56 . The radar controller  50  controls the transmitter  52  and the receiver  54  for performing the sending and receiving of signals through the antenna  56  based on aircraft data (i.e., position, heading, roll, yaw, pitch, etc.) received from the air data computer  46 , a Flight Management System (FMS), Inertial Navigation System (INS), and/or Global Positioning System (GPS). 
         [0025]    The air data computer  46  generates air data based on signals received from various aircraft flight systems. The radar system  40  transmits radar signals from the antenna  56  into space and receives return signals (reflectivity values) if a target  60 , such as a storm cell, is contacted by the transmitted radar signal. Preferably, the radar system  40  digitizes the return signals and sends the digitized signals to the display processor  42 . The display processor  42  translates the received return signals for storage in a three-dimensional buffer in the memory  43 . The display processor  42  then generates a two-dimensional image for presentation on the display device  44  based on any control signals sent from the user interface  48  or based on settings within the processor  42 . In alternative embodiments, the image may be in three dimensions, in a plan-view-image format, or presented on a vertical situation display (VSD). 
         [0026]    The translated return signals (return data), as determined by the radar system  40  or processor  42 , identify certain weather targets, such as rain/moisture, windshear, or turbulence. The type of weather target identified is based on a corresponding present algorithmic interpretation of the reflectivity values. The pilot can select the type of weather identified using the user interface  48 , or such weather type may be automatically displayed. The pilot may also be able to control range, gain, and display mode (e.g., AUTO weather, MANUAL weather, MAP mode). 
         [0027]    In an embodiment, the system  30  continuously scans the entire three-dimensional space in front of the aircraft, and stores all reflectivity data in an earth-referenced three-dimensional (or “volumetric”) memory buffer. This buffer is continuously updated with reflectivity data from new scans. The reflectivity data is extracted from the buffer to generate the desired display views without having to make (and wait for) view-specific antenna scans. With the three-dimensional volumetric buffer data, the display presentation is not constrained to a single tilt-plane that is inherent to conventional radar. The reflectivity data in the volumetric buffer is subjected to pattern recognition techniques discussed below. 
         [0028]    In an embodiment, recognizing hazardous weather conditions on the basis of volumetric radar data may be accomplished using a function that can map real-valued, stochastic radar data into a variety of known hazard categories. The appropriate mapping function can be empirically constructed using statistical machine learning techniques. 
         [0029]    In an embodiment, several pre-processing steps may be performed to appropriately condition the reflectivity data. First, data contaminated by noise artifacts can be corrected, or rejected, using signal processing techniques. Second, volumetric radar data features can be normalized so that differences in the dynamic range of various weather-system features do not negatively affect the classifier function (discussed in greater detail below). An exemplary set of such analyzed weather-system features is shown in, and discussed with reference to, Table 1 of “Classification of Meteorological Volumetric Radar Data Using Rough Set Methods,” J. F. Peters, et al.,  Pattern Recognition Letters  24 (2003) 911-920, which is hereby incorporated by reference in its entirety. Third, dimensionality reduction techniques, such as, for example, principal component analysis or Fisher discriminant analysis, can be used to eliminate redundant features in the data. Such reduction techniques can be used to identify and retain features that account for most of the variance in the data. 
         [0030]    As above alluded to, pre processed training data can be used to construct classifier functions that can map radar returns to hazard categories of interest. Two broad categories of classifier functions can be used: generative models or discriminative models. Generative models represent the distribution of features associated with each class of hazards. Discriminative models represent the boundaries between classes of hazards. The model construction process may employ a set of training labels that relate sample radar-return patterns of weather-system features, as described above, to hazard categories. These labels may be based on empirically observed objective meteorological measurements and/or the judgment of one or more human observers. Once constructed, classifier functions can estimate the likelihood of a given radar return sample belonging to a certain hazard category of interest. 
         [0031]    Since radar features are stochastic variables that are affected by environmental perturbations and measurement error, radar samples may be occasionally misclassified. To minimize the impact of these errors, in an embodiment, outputs from the classifier function may be smoothed over various time windows to dampen error perturbations. 
         [0032]    As discussed above herein, pattern recognition algorithms automatically detect pre-defined and pre-characterized weather threats. Improved awareness of these conditions may be provided on a plan-view, VSD or 3-D weather radar display as discussed below. As illustrated in  FIGS. 3 and 4 , an icon  300 ,  400  may be generated to the display device  44  to represent the hazard (in the examples illustrated in  FIGS. 3 and 4 , a U-Shape hazard) determined by the classifier function. 
         [0033]    Typically, the severe-weather hazard determined by the classifier function will be displayed on the display device along with one or more other weather systems (not shown) that are not severe, or that may otherwise not pose a significant threat to the aircraft on which the system  30  is carried. As such, the icon  300 ,  400  may be rendered in a manner that is visually distinguishable from the manner in which other, less severe systems are rendered. For example, the use of color, such as red or magenta, to fill the icon  300 ,  400  may be employed to enhance awareness of the hazardous weather system. In addition, or alternatively, to color, other visual coding techniques such as texture, type of fill pattern (dots, checkerboard, etc.) and density of fill pattern may be used to aid the flight crew in distinguishing the weather threat. Such an alternative-color or -texture scheme may also be implemented in a VSD display, as discussed below. 
         [0034]    In an embodiment, and as best illustrated in  FIG. 4 , only the most severe area  410  of the severe-weather system is distinguishably rendered in the icon  400 . 
         [0035]    In addition, a visual alert, such as the textual alerts “Caution Weather,” as shown in  FIG. 5 , or “Check Weather” could be provided on the weather radar display and/or on an Electronic Indication and Crew Alerting System (EICAS) display. The visual alert could be accompanied by a corresponding auditory alert (e.g., “Avoid weather”, “Check weather”) played over speakers or pilot headset (not shown) inside the cockpit of the aircraft on which the system  30  is carried. 
         [0036]    As illustrated in  FIG. 6 , and because principles of the invention employ 3-D reflectivity data, a similar visual-coding approach can be used on a VSD or other 3-D capable display to enhance awareness of the weather threat. In  FIG. 6 , an icon  600  serves to indicate the approximate longitude, latitude and range of the severe-weather system. Simultaneously displayed is an icon  610  that indicates the altitude and range of elements of the severe-weather system. In this VSD mode, the enhanced awareness of weather hazards can be presented on at least three VSD display modes, including along-track, selected-azimuth, and flight plan. 
         [0037]    An embodiment of the invention includes improved awareness and alerting of Flight Management System (FMS) flight path conflicts with determined weather hazards. Once a characteristic weather hazard is identified in the volumetric buffer using reflectivity data, its location can be compared to the FMS flight plan data for conflicts. As shown in  FIG. 7 , a determined weather hazard is visually coded using an icon  700  and displayed in relation to the legs  710   a - 710   c  of the FMS flight plan of the aircraft. This is accomplished on both plan-view and VSD displays. Note the flight plan legs  710   a - 710   c  are visually coded to enhance threat awareness, so as to alert the flight crew as which of the legs may be the most likely to put the aircraft in a perilous position with respect to the weather system. 
         [0038]    While a 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.