Abstract:
A hybrid air collision avoidance system (HACAS) is an air collision avoidance system with extended existing air avoidance capabilities and incorporated with new hybrid capabilities to perform hybrid air collision prediction and hybrid air collision avoidance. This system works in collaboration with two other systems, hybrid ground collision avoidance system, and obstacle avoidance dispatcher and resolver module to form a bi-directional feedback network for processing and exchanging of verification and validation collision avoiding data. With the embedded hybrid prediction and avoidance processing capabilities, the system not only can refine air collision avoidance solution to eliminate any induced ground collision situation, but also provide verification for ground collision avoidance resolution in the air domain; and subsequent validate the final avoidance solution.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part application of U.S. patent application Ser. No. 11/019,781, entitled “HYBRID GROUND COLLISION AVOIDANCE SYSTEM”, filed on Dec. 21, 2004, which is a continuation-in-part application of U.S. Pat. No. 6,873,269, entitled “EMBEDDED FREE FLIGHT OBSTACLE AVOIDANCE SYSTEM”, issued on Mar. 29, 2005, the teachings of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention (Technical Field)  
         [0003]     The present invention relates generally to the field of avionics for hybrid air collision avoidance systems to provide a complete coverage for air collision avoidance situations and validate a ground collision resolution for an induced air collision situation. More specifically, the present invention relates to a hybridized dual domain handler avoidance system for providing instantaneous real-time air collision avoidance that will have a dual domain of air and ground compatibility. The invention provides the capabilities for automatic air collision avoidance re-planning with the aid of feedback data generated by the hybrid ground collision avoidance system and verification and validation of the air collision avoidance condition for a ground collision avoidance solution.  
         [0004]     2. Background Art  
         [0005]     An aircraft equipped with an embedded hybrid air collision avoidance system (HACAS) has the capabilities to uniquely avoid an air collision situation without the implication of inducing a ground collision. These capabilities are achieved by incorporating a dispatcher and collision resolver module. This module provides filtering of collision solution data, evaluating, and routing feedback data resulting from cross-domain verification in hybrid modules. By inserting hybrid processing capabilities, the hybrid ground collision avoidance module can predict if the solution produced by the hybrid air collision avoidance module will have ground clearance and similarly, the hybrid air collision module can also predict if the solution produced by the hybrid ground collision module will not mis-guide the aircraft to an unsafe airspace.  
         [0006]     The development of an effective airborne obstacle collision avoidance system (CAS) has been the goal of the aviation community for many years. Airborne obstacle collision avoidance systems provide protection from collisions with ground and other aircraft. As is well appreciated in the aviation industry, avoiding collisions with ground and other aircraft is a very important endeavor. Furthermore, collision avoidance is a problem for both military and commercial aircraft alike. Therefore, to promote the safety of air travel, systems that avoid collision with other aircraft and terrain are highly desirable.  
         [0007]     A prior art midair collision avoidance system is described in U.S. Pat. No. 6,262,697, to Tran, entitled Midair Collision Avoidance System, which uses a flight path angle, closure range, and closure rate with an intruder aircraft to determine whether an midair collision condition exists. The resulting solution is determined from prediction calculations and provides warnings and appropriate generated maneuvers to avoid an air collision. This solution is applied solely to the intruder aircraft in the proximity air space information without taking the potential terrain condition induced by the air avoidance maneuver into consideration. Without the feedback and validation of the solution from a ground collision coverage domain, the air avoidance solution in many instances does not have a complete free clearance for obstacle avoidance.  
       SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)  
       [0008]     The present invention is a hybrid air collision avoidance system that preferably is an embedded system in an integrated mission management system (IMMS). The system is one of three main engines of an obstacle avoidance system. Each engine is designed and partitioned as a module. The obstacle avoidance management module continuously monitors the status of ground collision conditions and air collision conditions and the solutions generated by the two indicated engines, as described in U.S. patent application Ser. No. 10/446,526, now U.S. Pat. No. 6,873,269, entitled “EMBEDDED FREE FLIGHT OBSTACLE AVOIDANCE SYSTEM”. This module also serves as a filtering medium and a conduit for passing a selective collision resolution from one engine to another engine to allow a continuous evaluation and providing feedback about an “induced” collision condition on the indicated solution. If an “induced” collision is determined, the information from the evaluation is routed back to the originated solution module for re-planning to generate a more suitable avoidance solution to a complex obstacle situation. When there is no potential conflict with the provided solution, the obstacle management module will process the obstacle solution package along with the original tag to generate specific guidance data, and can include an obstacle avoidance situation display, and a synthesized audio message being specific to the situation to warn the flight crew. The second component is a hybrid ground collision avoidance engine, as described in U.S. patent application Ser. No. 11/019,781, entitled “HYBRID GROUND COLLISION AVOIDANCE SYSTEM”. This engine takes into account the global air traffic management (GATM) information, terrain data, air data, radar altitude, and the check data contained in the air collision verification data to determine if there is a conflict found in the second engine in order to predict and generate a suitable solution for ground and specific air avoidance solutions. The third component is a hybrid air collision avoidance module to predict and generate a suitable solution for air and specific ground avoidance solutions, which is described in this disclosure.  
         [0009]     The present invention processes navigation data, terrain data, air data and radar altitude, digitized data link data, along with a hybrid avoidance solution generated by the Hybrid Ground Collision Avoidance System to determine if there is a conflict in the air domain. If there is a conflict, the specific information of location, avoidance maneuver path and time markers will be routed to the Hybrid Ground Collision Avoidance System (HGCAS). This information will allow the HGCAS to verify the solution compatibility with the operating ground situation. If the feedback data identifies a positive incompatibility condition found in the ground solution, then the system will apply a re-planning process with the specific feedback information to refine the avoidance solution. If the revised solution is again verified, it takes the feedback data of predicting ground collision and provides a cross-feed of collision and avoidance data produced by the two avoidance modules by implanting unique air avoidance capabilities in the hybrid terrain collision avoidance engine and unique ground avoidance capabilities in the hybrid air collision avoidance module, along with the arbitration and controlling capability in the obstacle avoidance management module, which results in producing an obstacle avoidance solution.  
         [0010]     It is an object of the present invention to provide air collision avoidance control guidance that is compatible with instantaneous operating air space and localized terrain and feature situations, and unambiguous warnings to any flight crew operating an aircraft. The prior art control guidance and warnings produced from a single domain system, in some instances, can create ambiguity and uncertainty to the operation of the flight crew.  
         [0011]     It is an object of the present invention to provide a suggestive modification to the solution of the hybrid ground collision avoidance system to be compatible with the air traffic situation.  
         [0012]     It is also an object of the present invention to provide a hybrid air collision avoidance system that is capable of verifying and validating ground collision avoidance solution for induced air collision condition.  
         [0013]     It is a further object of the present invention to provide a hybrid air collision avoidance system, which is capable of generating an air collision avoidance solution by re-planning with the aiding of feedback data from a hybrid ground collision avoidance system.  
         [0014]     Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating a preferred embodiment of the invention and are not to be construed as limiting the invention. In the drawings:  
         [0016]      FIG. 1  is a diagram showing the modular structure of the preferred hybrid air collision avoidance system with three collaborative system modules in accordance with the present invention.  
         [0017]      FIG. 2  is a functional block diagram showing system components and the interfaces between the Hybrid Air Collision Avoidance System and other avionics systems, the Obstacle Avoidance Dispatcher and Resolver system, and Hybrid Ground Collision Avoidance System in accordance with the present invention.  
         [0018]      FIG. 3  is a mode transition diagram for three modes of the Hybrid Air Collision Avoidance System in accordance with the present invention.  
         [0019]      FIG. 4  is a logical flow diagram showing system behaviors of the Hybrid Air Collision Avoidance system in accordance with the present invention.  
         [0020]      FIG. 5  is a logical flow diagram showing the process of determination for an air collision condition and an induced air collision condition as a feedback to the Hybrid Ground Collision Avoidance module in accordance with the present invention.  
         [0021]      FIG. 6  is a logical flow diagram showing the computations of a hybrid air collision avoidance process for providing air domain feedback, modification to the air collision avoidance solution to remove an induced ground collision situation, and generation of air collision an avoidance solution in accordance with the present invention.  
         [0022]      FIG. 7  is a logical flow diagram showing the process for determining compatibility with an air traffic situation for a ground avoidance solution and generating suggestive modifications to a ground collision avoidance solution in accordance with the present invention.  
         [0023]      FIG. 8  is a logical flow diagram showing the computation process for modifying an air collision avoidance solution based on feedback data from a HGCAS and initiating new solution re-planning in accordance with the present invention.  
         [0024]      FIG. 9  is a logical flow diagram showing the computation process for providing feedback data to the HGCAS and organizing the air collision avoidance solution data to enable the HGACS to perform cross-domain verification and validation in accordance with the present invention.  
         [0025]      FIG. 10  is a graphical view of a vertical profile showing a potential occurrence of an induced ground collision condition due to performing an un-correlated air avoidance maneuver in accordance with the present invention.  
         [0026]      FIG. 11  is a graphical view of a vertical profile with fusing air collision avoidance maneuver with ground suggested maneuver modifications to remove an induced ground collision condition in accordance with the present invention.  
         [0027]      FIG. 12  is a graphical view of vertical and lateral profiles generated from an aircraft performing re-planning maneuvers, including lateral and vertical maneuvers to achieve an air collision avoidance situation and being free from an induced ground collision condition in accordance with the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     (Best Modes For Carrying Out The Invention)  
       [0028]     Referring to  FIG. 1 , there is shown a modularized structural diagram of three-hybrid embedded modules that make up the preferred free flight obstacle avoidance system. Each module provides a set of unique functional capabilities enabling collaborative operations between the three modules. Hybrid Ground Collision Avoidance Module (HGCAM)  67  operates with three different modes, the Standby mode, the Hybrid Ground Collision Prediction (HGCP) mode and hybrid Ground Collision Avoidance (HGCA) mode. To predict ground collision conditions on a continuous basis, HGCAM  67  relies on terrain and features data  151 , ground collision sensor health data  152 , and aircraft navigation state vector and radar data  153 . In the HGCP mode, HGCAM  67  uses the air avoidance resolution information contained in air avoidance cross-domain feedback data  155  with the indicative inputs to determine terrain clearance conditions for an indicated air avoidance solution. HACAM  69  also operates in three modes, the Standby mode, the Hybrid Air Collision Prediction (HACP) mode, and the Hybrid Air Collision Avoidance (HACA) mode. To predict an air collision condition on a continuous basis, HACAM  67  relies on the data contained in direct digital data link  156 , routing digital data link  157 , air collision sensor health data  158 , and aircraft navigation state vector and radar data  153 . In the HACP mode, HACAM  69  uses the ground avoidance solution information contained in the ground avoidance cross-domain feedback data  162  along with the indicative inputs to determine air clearance conditions for an indicated ground avoidance solution. To achieve operational compatibility for the final obstacle avoidance solution in the dual-domains of ground and air traffic, obstacle avoidance dispatcher and resolver module (OADRM)  65  will operate based on the controls and data from avoidance mode controls  168  and operation and configuration data  169  in dispatching an avoidance solution along with the supportive data produced from one hybrid module and consumed by another hybrid module. The routing information will enable the process of cross-domain verification and validation for an avoidance solution. If an avoidance solution results in an “induced” collision condition in the verifying phase, then OADRM  65  will correlate and provide the originator module with verification feedback, air avoidance cross-domain feedback data  155  for HGCAM  67  and ground avoidance cross-domain feedback data  162  for HACAM  67 . If an “induced” condition is determined, the detailed information of the “induced” condition is included in the feedback data. The originator module will use the feedback data to generate a more applicable solution, comprising either modifying the original solution or generating a new solution. OADRM  65  monitors the data contained in ground collision avoidance resolution track file  154  to determine if a predicted ground collision condition exists. If the condition exists, OADRM  65  sends a request along with the data extracted from ground collision avoidance track file  154  to HACAM  69  to perform verification for an air traffic situation. After determining an air traffic situation for an indicated ground collision avoidance solution, HACAM  69  provides feedback information via air collision avoidance resolution track file  161  to OADRM  65 . This module will process the feedback data and package the data to be routed back to HGCAM  67 . Similarly, OADRM  65  checks for compatibility indicators in the ground collision avoidance resolution track file  154  for an air traffic avoidance resolution and then determines appropriate data to send back to HACAM  69  through ground avoidance cross-domain feedback data  162 . If compatibility is obtained, OADRM  65  will overlay the obstacle data with the map data and the air traffic data  167  to provide obstacle avoidance display images  163 . The display data is then sent to display management system  90  for image rendering. The obstacle resolution along with the aircraft dynamics navigation vector are packed in broadcasted obstacle avoidance information  164  and sent to communication management system  40 . OADRM  65  sets the state of the obstacle avoidance mode and feeds the control target through the obstacle guidance control laws to generate proper mode and guidance commands  166  to flight control system  70 . Filtered obstacle avoidance resolution data  165  is sent to flight management system  80  for flight plan updates and informs air traffic management of impending changes to the active flight plan. Similarly, OADRM  65  monitors the data contained in air collision avoidance resolution track file  161  to determine if a predicted air collision condition exists. If the condition exists, OADRM  65  extracts the information from air collision avoidance resolution track file  161  and sends it to HGCAM  67  to perform verification via air avoidance cross-domain feedback data  155 . After verifying for the comparability of the air solution in the ground domain, HGCAM  67  transmits the feedback information for the air resolution to ground collision avoidance resolution track file  154 . OADRM  65  checks for air compatibility provided for the ground solution in air collision avoidance track file  161  and sends back this information to HGCAM  67  through air avoidance cross-domain feedback data  155 . If compatibility is obtained, OADRM  65  will overlay the obstacle data with ground situation awareness image data  159  and send this image data to display management system  90 . In addition, OADRM  65  generates obstacle avoidance mode and guidance commands  166  for flight control system  70  and sends the re-planned flight path to flight management system  80  for flight plan updates and fuel and time performance predictions. OADRM  65  also has the capability to filter, select, and tag the data provided by hybrid modules  67  and  69 , prior to routing the packaged data for verification and validation in a different domain.  
         [0029]     Referring to  FIG. 2 , there is shown a functional block diagram of HACAS  69  from  FIG. 1 . HACAS  69  preferably has a bi-directional communication means with Obstacle Avoidance Dispatcher and Resolver Module (OADRM)  65  and Navigation Management Function Module  71  through an intra-module bus  234 . Global Bus Data Mapping  230  handles data transferred between internal components of HACAS  69 . External communication with other avionics systems includes Data Loader (DLDR)  251 , Radar Altimeter  252 , Barometric Altimeter  254 , Embedded Global Positioning and Inertial System (EGI)  256 , and Flight Guidance Control System  258 . Communication is controlled and scheduled for transmitting and receiving by System Bus Input and Output Controller  232  on avionics bus  236 . HACAS  69  is built with a set of components designed to perform the hybrid air collision prediction function and the hybrid air collision avoidance function. The first component is a hybrid air collision avoidance module controller  201 . This component determines timing and a processing sequence of all components contained in this module and activates controls through control scheduler  231 . Air collision avoidance operating modes component  216  periodically evaluates system conditions to determine the active mode and state for the module. After completion of system power-up test, air collision data initialization component  214  performs initialization for all working data buffers and sets the control signals to safe states. Hybrid air collision predictor component  218  determines an air collision condition based on closure time and closure rate provided by flight path interception computations with instantaneous projection of inertial flight paths of the host aircraft and intruder aircraft. If extraction of ground traffic avoidance resolution component  207  determines that there is a request to verify air domain compatibility for a ground collision avoidance resolution, then this component will unpack and convert the provided data to a specific format needed by hybrid air collision predictor  218 . With the availability of the formatted ground collision avoidance resolution data, hybrid air collision predictor  218  provides an evaluation of a ground collision avoidance solution with the intermediate air traffic situation to determine if an induced air collision condition exists. To maintain a currency of air traffic redundancy, air traffic data management component  224  continuously filters and updates the data file contained tracking intruder aircraft data. The current intruder tracking file is an important input to the processing of two components, hybrid air collision predictor  218  and hybrid air collision avoidance  220 . The re-evaluating maneuver plan component  222  re-establishes the process of collision avoidance, which will be used by hybrid air collision avoidance  220  in generating a new air avoidance solution. If there is an indication of an induced ground collision in the feedback data, hybrid air collision avoidance component  220  uses the re-evaluating maneuver plan to generate a new solution that will be compatible with the ground domain and have the induced ground collision condition to be removed. To resolve an induced ground collision situation, the extraction of feedback data from ground avoidance component  209  unpacks the data and converts them to the format to be expected by hybrid air collision avoidance component  220 . If there is an air collision condition and hybrid air collision avoidance component  220  completes the generation of the air collision avoidance solution, the construction of hybrid avoidance data component  203  takes the output data produced by hybrid air collision predictor  218  and hybrid air collision avoidance component  220  to form a hybrid data package of an air collision avoidance solution. This package is sent to OADRM  65  and subsequently, the data in this package is processed by HGCAS  67  to verify and validate for ground domain compatibility. For the feedback of a ground collision avoidance solution, formulation of feedback data for ground solution  205  will collect verification data produced in air collision avoidance operating modes component  216  along with the suggested solution produced by hybrid air collision avoidance component  220  into a hybrid data package. The data is then transmitted to OADRM  65 . Extraction of feedback data from ground avoidance solution component  209  processes the feedback data to evaluate if the generated air traffic collision avoidance resolution is compatible with the ground domain. If there is an induced ground collision condition, the re-evaluating maneuver plan for removing induced ground collision component  222  takes into consideration of the ground collision information, such as a predicted ground collision location and time along with suggestive maneuver flight path to generate a new air traffic collision avoidance resolution. Redundancy data management component  224  selects the appropriate sensor data to be used by other components to determine a mode of operation, air collision prediction, and air collision avoidance resolution generation. The real-time digitized air traffic data management component  211  processes the air traffic data provided by the communication management module  73 .  
         [0030]     Referring to  FIG. 3 , there is shown a state transition diagram providing necessary logic to allow a mode transition to take place. The three system modes of HACAS  69  are: standby mode  300 , hybrid air collision prediction mode  310 , and hybrid air collision avoidance mode  320 . At system power-up, after completing system power-up test and initialization  299 , HACAS  69  is placed in standby mode  300 . From standby mode  300 , if the data in navigation vector is valid, the altitude sensors are valid, and tactical digitized datalink is available  302 , the module will make a transition to hybrid air collision prediction mode  310 . Also from hybrid ground collision prediction mode  310 , the module will make a transition back to standby mode  300 , if either the navigation vector is invalid, or the altitude sensors are invalid, or tactical digitized datalink is not available  304 . From hybrid air collision avoidance mode  320 , the module will make a transition back to hybrid air collision prediction mode  310 , if the air collision avoidance flag is set to true  314 . From hybrid air collision prediction mode  310 , the module will make a transition to hybrid air collision avoidance mode  320 , if air collision prediction is complete, and air collision condition exists, and tactical digitized datalink is valid  312 . From hybrid air collision avoidance mode  320 , the module will make a transition to standby mode  300  if either the navigation vector is invalid, or altitude sensors are invalid, or tactical digitized datalink is not available  306 .  
         [0031]     Referring to  FIG. 4 , there is shown a flow diagram outlining system behaviors of the HACAS  69 . The initial step is start  400 . The module reads system mode state  402 . A test is then performed to determine if the module is in power-up or warm start  404 . If the answer is affirmative  408 , the module performs data initialization and sets control signals to defaulted states  410 . Otherwise, the module will proceed with step  406  to read navigation vector and barometric altitude data  412 . The module will then update the air traffic tracking file  414 . A test is made to determine if hybrid collision prediction mode is active  416 . If hybrid collision prediction mode is not active  418 , the module will set up caution, warning and advisory messages  420 . If an affirmative determination  422  is made, then the module will perform hybrid air collision prediction  424 . A test is made to determine if there is a related air collision condition or a feedback from HGCAS  426 . If there is no affirmative determination  428  for this test, then the module will set the feedback flag to false and cross-domain (CD) verification and validation to false  430 . If there is an affirmative determination  432  for this test, then the module will perform hybrid air collision avoidance  434 . After processing step  434 , the module will update redundancy cross channel data management  436  and then go to the end of process  440  waiting for a next processing cycle to repeat the entire process from step  400 .  
         [0032]     Referring to  FIG. 5 , there is shown a flow diagram outlining the process steps of hybrid ground collision predictor  218 . The initial step is start  442 . The module reads the request from the HGCAS  444 . A test is performed to determine if there is a request for verifying induced air collision condition  446 . If there is an affirmative answer  448 , the module will extract the track angle from verified data HGCAS  450 . The module will then determine a track intercept condition between the host aircraft and intruder aircraft  452 . A test is made to determine if track intercept condition is set to true  454 . If there is no affirmative determination  455  for this test, the module will set up a feedback record for “no induced” air collision  467 . If an affirmative determination  456  is made, then the module will compute closure rate, based on avoidance velocity being projected on the instantaneous line-of-sight from the host to intruder aircraft, and closure range in terms of inertial distance and time  458 . With the computed closure range and closure rate, the module will correlate this data with the air collision model  460 . A test is made to determine if there is an induced air collision condition  462  resulting from the model-base data in step  460 . If there is no affirmative determination  463  for this test, the module will proceed with the process in  467 . If an affirmative determination  464  is made, then the module will build a data record to provide the data of induced air collision condition data  466  and then terminate this process at step  468 . From the test in step  446 , if there is no affirmative determination  447 , the module will compute the track angle for the host  500 . In step  502 , the module extracts the intruder data to compute the track angle of the intruder aircraft. The module will resolve the reference to determine the track intersection condition between the host and intruder aircraft  504 . A test is made to check the intercept condition  506 . If there is no affirmative determination  507  for this test, the module will set the flag for air collision condition to false  526 . If an affirmative determination  508  is made, then the module will compute closure rate based on actual air speed being projected on the instantaneous line-of-sight from the host to intruder aircraft, and closure range in terms of inertial distance and time  510 . The module will correlate the computed range and closure rate data with the air collision model  512 . A test is performed to determine if there is an air collision condition based on the results of the model-base correlation  514 . If there is no affirmative determination  516  for this test, the module will set the flag for air collision condition to false  526 . If there is an affirmative determination  518 , the module will set the flag for air collision condition to true  520 .  
         [0033]     Referring to  FIG. 6 , there is shown a flow diagram outlining the preferred hybrid air collision avoidance process. The initial step is start  550 . The module reads the data produced by hybrid air collision predictor  552 . The next step is for the module to get the flight phase data for an intruder aircraft  554 . A test is made to determine if induced air collision flag is set to true  556 . If an induced air collision condition does exist  560 , the module sets air collision avoidance flag to true  562 . The module will then process suggestive air collision avoidance solution for HGCAS feedback  564 . If there is no affirmative determination  558  for the test in  556 , the module will perform another test to determine if air collision flag is set to true  566 . If an affirmative determination  570  is made, then the module will set air collision avoidance flag to true  572 . Otherwise, if there is no affirmative determination for the test  468 , the module will set air collision avoidance flag to false  584 . A test is made to determine if there is an induced ground collision condition in the feedback data  574 . If an affirmative determination  578  is made, the module initiates a process of modifying the air avoidance resolution to remove induced ground collision condition  580 . If there is no affirmative determination for the test  576 , the module will generate an air collision avoidance resolution  582 . The module completes the execution for this process at the end  586 .  
         [0034]     Referring to  FIG. 7 , there is shown a flow diagram outlining the process of determining the compatibility for a ground collision avoidance solution with air traffic and generating suggestive modification to the solution if necessary for feedback to the HGCAS. The initial step is start  600 . The module reads the flight phase of the host aircraft provided by the HGCAS  602 . A test is performed to determine if both the host aircraft and the intruder aircraft are in climb  604 . If an affirmative determination is made  608 , the module will perform another test for the barometric altitude  610 . If the barometric altitude of the host aircraft is greater than that of the intruder aircraft  614 , then the module will set the compatibility flag for the ground avoidance solution to true  616  and then terminate at the end step  638 . Otherwise, if the barometric altitude of the intruder aircraft is above the host aircraft  612 , then the module will set the compatibility flag to false for the ground collision avoidance solution  618 . The next step  620 , the module will generate suggestive solution for the HGCAS to re-plan with either reducing climb rate or combined with performing lateral maneuver. If both host and intruder aircraft are not in climb phase  606 , the module performs another test to determine if the intruder aircraft is in descent and the host aircraft is in climb  622 . If an affirmative determination can be made  626 , the module continues with another test for barometric altitude  628 . If the barometric altitude of the host aircraft is greater than that of the intruder aircraft  632 , the module will set the compatibility flag for the ground collision avoidance solution to true  634 . Otherwise, if the barometric altitude of the intruder aircraft is greater than that of the host aircraft  630 , the module will generate suggestive solution for the HGCAS to re-plan with lateral maneuvering and commanding the intruder aircraft to reduce the descent rate  636 . For the test in  622 , if there is no affirmative determination  624 , the module will proceed to the end of the process  638 .  
         [0035]     Referring to  FIG. 8 , there is shown a flow diagram outlining the process of evaluating the suggestive modification of the air traffic collision avoidance resolution. The initial step is start  650 . The module reads the suggestive modifications to the air traffic collision avoidance resolution  652  generated by the HGCAS. The module evaluates the modified resolution as a part of resolution validation for achievable air avoidance situation  654 . A test is made to determine the result of the validation process  656 . If the validation flag is set to true  660 , the module will apply the modified resolution to the validated air traffic avoidance resolution  662  and then end the process at step  667 . If the validation flag is set to false  658 , the module will initiate a re-plan with lateral maneuver and combined with descent for a revised resolution  664 . The module will then set up a request for verification and validation for the new resolution with the HGCA  665 .  
         [0036]     Referring to  FIG. 9 , there is shown a flow diagram outlining the preferred hybrid air collision avoidance process. The initial step is start  700 . The module reads the data produced by hybrid air collision predictor  702 . A test is made to determine if an air collision condition exists  704 . If an air collision condition doesn&#39;t exist  706 , the module sets the cross-domain ground verification and validation flag to false  710 . A test is made to determine if an induced air collision condition exists  712 . If an induced air collision condition does not exist  714 , the module sets the feedback flag for ground avoidance solution to true  718 . If an affirmative determination  716  is made, the module initiates a process of modifying the ground avoidance resolution to remove induced air collision condition  720 . In step  724 , the module sets feedback flag for ground avoidance resolution to true. After completing either step  718  or step  724 , the module sets up the feedback data to send to HGCAS  726 . The end of this step is connected to node B. Returning to test  704 , if an affirmative determination  708  can be made, the module will perform another test  728  to determine if the cross-domain air verification and validation flag is set to true. If it is set to true  730 , the module initiates another test to determine if the induced air collision flag is set true  764 . If it is set to true  766 , the module performs a modification to the ground avoidance solution in order to remove induced air collision  774 . If the result from the test is negative  768 , the module evaluates the ground avoidance resolution for adaptability to air avoidance  770 . At the end of processing in either  770  or  774 , the module sends the feedback data to HGCAS  772 . The module makes a connection to node B. If the cross-domain ground verification and validation flag is not set to true  732 , the module makes a test to determine if there is feedback data from HGCAS  734 . If there is no feedback data from HGCAS  736 , the module will then perform air collision avoidance process  760 . The module stores data and process stages in the event that it is necessary to perform re-plan  762 . The module then connects with node A. If an affirmative determination  738  can be made, the module will correlate collision avoidance identification  740 . A test is made to determine if there is match for avoidance identification  742 . If there is not a match  746 , the module performs air collision avoidance process  760 . If there is a match in collision identification  744 , the module initiates another test to determine if there is an induced ground collision condition  748 . If the test is negative  750 , the module moves to step  760 . If an affirmative determination  752  is made, the module re-stores the data for air avoidance re-planning  754 . The next step for the module is to extract feedback data associated with induced ground collision condition  756 . The module evaluates and re-plans if it&#39;s necessary in order to remove induced ground collision condition  758 . The module connects to node A. From node A, the module formulates the air avoidance data for cross-domain ground verification and validation  776 . The module completes the execution for this process at end  778 .  
         [0037]     Referring to  FIG. 10 , there is shown a graphical view of a vertical profile showing an induced ground collision condition due to the initiation of un-correlated maneuver that is intended to avoid a predicted air traffic collision condition. If the aircraft  802  continues on the flight path  804 , the HACAS will predict an air collision condition  856  with the intruder aircraft  800  on flight path  806 . The initial solution generated for the aircraft is to initiate a descent at  805 . The HGCAS verifies the air avoidance solution for any ground domain conflicts and provides a feedback to indicate an induced ground collision situation at location  810  on the projected vertical profile  808 . With the suggestive modification to the air collision resolution from the HGCAS, thee HACAS will either modify the maneuver of the air avoidance resolution or perform a re-plan to remove induced ground collision condition.  
         [0038]     Referring to  FIG. 11 , there is shown a graphical view of correlating an air avoidance profile with the local terrain. The initial solution provided by the HACAS for aircraft  800  to avoid midair collision situation at  850  is to initiate a descent. The HGCAS provides a feedback to indicate an induced ground collision condition would occur at  852  on the vertical profile  860  along with a suggestive modification to air traffic re-solution with an initiation of an altitude capture at time t M-10    864  on the predicted path  856 . This will allow the HACAS to incorporate this suggestive modification and evaluate if the modified re-solution is still applicable with the air traffic situation. This provides a way to remove the induced ground condition and still have sufficient altitude separation  868  from intruder aircraft  802 .  
         [0039]     Referring to  FIG. 12 , there is shown a graphical view of vertical profiles corresponded with re-planning to avoid air collision condition and induced ground collision situation. If aircraft  800  follows flight path  888 , the HACAS predicts the aircraft on the collision course  884  with the intruder aircraft  802  on the flight path  886 . With the initial solution, by initiating a descent, the aircraft  800  will face with problem of induced ground collision condition at  881  on the vertical terrain profile  878 . However, with the feedback data from the HGCAS, the HACAS will be able to modify the resolution with suggestive maneuvers by combining descent with lateral maneuvering to get to an air space being away from air collision conflict and at the same time, the induced ground collision condition also is removed as shown on the vertical profile  880 .  
         [0040]     Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above, are hereby incorporated by reference.