1+_____________________________________________________________________
 ] AUTHOR:            ]                             ] DR:              ]
 ] J. MAGLEY          ]    PASS PROGRAM NOTE        ]      64501 *     ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:  07/30/87  ]
 ] SSOAS/(281)335-2275]      RELEASE NOTE( )        ] REV B: 12/05/97  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ]  OI-20 AND SUBS               ]  CREW (X)  GROUND ( )  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW ( )  GNC (X)  VU ( )  SM/PL ( )] G2                              ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA:  ORBIT, TARGET                                   ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: 5.10                                           ]
 ]_____________________________________________________________________]
 ] TITLE: ON-ORBIT TARGETING PROBLEMS WITH NON-ZERO ELEVATION ANGLE    ]
 ]_____________________________________________________________________]
 ]                                                                     ]
 ]         * REFERENCE DRS 63999, 64515, AND 100531                    ]
 ]                                                                     ]
 ] "TGT EL ANG" DURING NORMAL OPERATIONS:                              ]
 ]                                                                     ]
 ] THE MC2 TARGETING ALGORITHM MAY FAIL TO CONVERGE ON AN ELEVATION    ]
 ] ANGLE TIME WITHIN 10 ITERATIONS DUE TO PERTURBATIONS IN THE PRE-MC2 ]
 ] TRAJECTORY.  THIS OCCURS WHEN THE PRE-MC2 TRAJECTORY DOES NOT       ]
 ] INTERCEPT THE DESIRED MC2 TARGET ELEVATION ANGLE, AND WILL RESULT   ]
 ] IN A CLASS 3 "TGT EL ANG" SM ALERT.  A MC2 TARGET SOLUTION WILL BE  ]
 ] COMPUTED TO OCCUR NEAR THE TRAJECTORY LOCAL MAXIMUM ELEVATION ANGLE.]
 ] NOTE THAT THE "ORBT" PROFILE INCREASES THE PROBABILITY OF THE ALARM ]
 ] OCCURRING.                                                          ]
 ]                                                                     ]
 ] USER RESPONSE:                                                      ]
 ]  DISREGARD THE ALERT MESSAGE (SERVES ONLY AS A WARNING) AND COMPLY  ]
 ]  WITH FDF PROCEDURES FOR A MC2 BURN.  IF TIG CHANGE IS BETWEEN THREE]
 ]  MINUTES EARLY AND SEVEN MINUTES LATE USE NOMINAL MC2 PROCEDURES.   ]
 ]  IF THE TARGET SOLUTION RESULTS IN A TIG CHANGE MORE THAN THREE     ]
 ]  MINUTES EARLY OR SEVEN MINUTES LATE, COMPLY WITH MC2 FDF PROCEDURES]
 ]  WHICH CALL FOR USING MC2 TARGET NUMBER 19.                         ]
 ]                                                                     ]
 ]THE FOLLOWING SPECIAL CASES RELATED TO NON-ZERO ELEVATION ANGLE      ]
 ]RENDEZVOUS TARGETING EXIST:                                          ]
 ]                                                                     ]
 ] DESCRIPTION FOR DR 64501:                                           ]
 ]  IF THE CREW ENTERS A RELATIVE STATE FOR USE BY ORBIT TARGETING BY  ]
 ]ENTERING NON-ZERO VALUES FOR ANY OF ITEMS 7 THROUGH 12 ON THE ORBIT  ]
 ]                                                                     ]
 ]              - CONTINUED ON SUPPLEMENT PAGES -                      ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]SSOAS:  JOHN MAGLEY       DATE 01/20/98]                             ]
 ]      ------------------      ---------]                             ]
 ]ASD:   ERIC C. BINGHAM    DATE 01/21/98]                             ]
 ]      ------------------      ---------] DARRELL E. STAMPER 01/26/98 ]
 ]PF MGR:  GENE MCSWAIN     DATE 01/21/98]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
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1+_____________________________________________________________________
 ]                       SUPPLEMENTAL SHEET                            ]
 ]_____________________________________________________________________]
 ] AUTHOR:            ]                             ] DR:              ]
 ] J. MAGLEY          ]    PASS PROGRAM NOTE        ]      64501       ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:  07/30/87  ]
 ] SSOAS/(281)335-2275]      RELEASE NOTE( )        ] REV B: 12/05/97  ]
 ]____________________]_____________________________]__________________]
 ]                                                                     ]
 ] TITLE: ON-ORBIT TARGETING PROBLEMS WITH NON-ZERO ELEVATION ANGLE    ]
 ]_____________________________________________________________________]
 ]                                                                     ]
 ]TARGETING DISPLAY (SPEC 34), AND THE ELEVATION ANGLE (ITEM 6) IS NON-]
 ]ZERO, WHEN A COMPUTE T1 (ITEM 28) IS PERFORMED THE RELATIVE STATE    ]
 ]WILL BE IGNORED.                                                     ]
 ]                                                                     ]
 ] USER RESPONSE:                                                      ]
 ]  IF THE RELATIVE STATE IS DESIRED TO BE USED, RESELECT THE TARGET   ]
 ]SET VIA ITEM 1, RE-ENTER THE RELATIVE STATE, AND ENSURE THAT THE     ]
 ]ELEVATION ANGLE (ITEM 6) IS ZERO PRIOR TO PERFORMING A COMPUTE T1    ]
 ](ITEM 28).                                                           ]
 ]                                                                     ]
 ] DESCRIPTION FOR DR 63999:                                           ]
 ]  IF A COMPUTE T1 (ITEM 28) IS PERFORMED ON THE ORBIT TARGETING DIS- ]
 ]PLAY (SPEC 34) USING A TARGET SET WITH A NON-ZERO ELEVATION ANGLE    ]
 ](ITEM 6), AND THAT TARGET SET REPRESENTS A MANEUVER THAT WILL BE DONE]
 ]NEAR APOGEE OR PERIGEE, THE ORBIT TARGETING SOFTWARE MAY CONVERGE TO ]
 ]A SOLUTION FOR A MANEUVER DIFFERENT FROM THE MANEUVER THAT IS DESIR- ]
 ]ED.  THIS CAN OCCUR IF THE SAME ELEVATION ANGLE EXISTS BOTH BEFORE   ]
 ]AND AFTER THE APSIS.                                                 ]
 ]                                                                     ]
 ] USER RESPONSE:                                                      ]
 ]  IF POSSIBLE, AVOID THE USE OF NON-ZERO ELEVATION ANGLES IN TARGET  ]
 ]SETS FOR MANEUVERS NEAR APOGEE OR PERIGEE.  IF SUCH A TARGET SET IS  ]
 ]TO BE USED, ENSURE THAT (TI_TIG + DEL_X_GUESS(2) ), WHERE DEL_X_     ]
 ]GUESS(2) IS AN ILOAD (CURRENT VALUE IS +100.0 SECONDS), YIELDS A TIME]
 ]BEFORE THE APSIS IF THE DESIRED MANEUVER SHOULD OCCUR BEFORE THE     ]
 ]APSIS OR YIELDS A TIME AFTER THE APSIS IF THE DESIRED MANEUVER SHOULD]
 ]OCCUR AFTER THE APSIS.                                               ]
 ]                                                                     ]
 ] DESCRIPTION FOR DR 64515:                                           ]
 ]  IF A COMPUTE T1 (ITEM 28) IS PERFORMED ON THE ORBIT TARGETING DIS- ]
 ]PLAY (SPEC 34) USING A TARGET SET WITH A NON-ZERO ELEVATION ANGLE    ]
 ](ITEM 6), AND THE ELEVATION ANGLE SEARCH FINDS A T1 TIG IN THE PAST, ]
 ]THEN THE RESULTANT MANUEVER SOLUTION WILL BE INCORRECT AND WILL NOT  ]
 ]BE TRANSFERRED PROPERLY TO GUIDANCE, BUT NO ALARM WILL BE ANNUNCIAT- ]
 ]ED.  THE DISPLAYED T1 TIG OF THE MANEUVER ON THE ORBIT TARGETING DIS-]
 ]PLAY WILL BE IN THE PAST, AND THE "MANEUVER IN THE PAST" ASTERISK    ]
 ]WILL BE PRESENT NEXT TO THE MNVR TIG (WHICH WILL ALSO BE IN THE      ]
 ]PAST).  IF A GUIDANCE LOAD (ITEM 22) IS PERFORMED ON THE ORBIT MAN-  ]
 ]EUVER EXECUTE DISPLAY, A "TGT DELTA-T" ALARM WILL BE ANNUNCIATED AND ]
 ]LARGE VALUES FOR VGO AND TGO WILL BE DISPLAYED.                      ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
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1+_____________________________________________________________________
 ]                       SUPPLEMENTAL SHEET                            ]
 ]_____________________________________________________________________]
 ] AUTHOR:            ]                             ] DR:              ]
 ] J. MAGLEY          ]    PASS PROGRAM NOTE        ]      64501       ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:  07/30/87  ]
 ] SSOAS/(281)335-2275]      RELEASE NOTE( )        ] REV B: 12/05/97  ]
 ]____________________]_____________________________]__________________]
 ]                                                                     ]
 ] TITLE: ON-ORBIT TARGETING PROBLEMS WITH NON-ZERO ELEVATION ANGLE    ]
 ]_____________________________________________________________________]
 ]                                                                     ]
 ] USER RESPONSE:                                                      ]
 ]RESPONSE DEPENDS ON THE CAUSE OF TIG BEING IN THE PAST:              ]
 ]                                                                     ]
 ]*  IF DUE TO ERRONEOUS TARGET SET DATA, ENTER CORRECT DATA, PERFORM  ]
 ]   ORBIT TARGET LOAD (ITEM 26), AND REPEAT THE COMPUTE T1 (ITEM 28). ]
 ]                                                                     ]
 ]*  IF DUE TO DESIRED MANEUVER BEING NEAR APOGEE OR PERIGEE, REFER TO ]
 ]   RESPONSE FOR DR 63999.                                            ]
 ]                                                                     ]
 ]*  IF DUE TO ERRORS IN THE VEHICLE STATES OR DUE TO UNDETERMINED     ]
 ]   REASONS, RESELECT THE TARGET SET VIA ITEM 1, ZERO THE ELEVATION   ]
 ]   ANGLE VIA ITEM 6, ENSURE THAT THE T1 TIG TIME IS THE NOMINAL EX-  ]
 ]   PECTED T1 TIG FOR THIS MANEUVER, PERFORM AN ORBIT TARGET LOAD     ]
 ]   (ITEM 26), AND REPEAT THE COMPUTE T1 (ITEM 28).                   ]
 ]                                                                     ]
 ] DESCRIPTION FOR DR100531:                                           ]
 ]  IF A COMPUTE T1 (ITEM 28) IS PERFORMED ON THE ORBIT TARGETING DIS- ]
 ]PLAY (SPEC 34) USING A TARGET SET WITH A DESIRED ELEVATION ANGLE     ]
 ](ITEM 6) NEAR 90 DEGREES OR 270 DEGREES, THE ELEVATION ANGLE SEARCH  ]
 ]MAY FAIL TO CONVERGE DURING THE COMPUTATIONS (INDICATED BY ANNUNCIA- ]
 ]TION OF THE "TGT EL ANG" ALARM).  CONVERGENCE FAILURE WILL OCCUR IF  ]
 ]THE MAGNITUDE OF THE OUT-OF-PLANE (DY) COMPONENT OF THE RELATIVE     ]
 ]STATE EXCEEDS THE MAGNITUDE OF THE DOWNRANGE (DX) COMPONENT OF THE   ]
 ]RELATIVE STATE AT THE TIME THE DESIRED ELEVATION ANGLE WOULD EXIST   ]
 ]IF DY WERE EQUAL TO ZERO.                                            ]
 ]                                                                     ]
 ] USER RESPONSE:                                                      ]
 ]  IF POSSIBLE, AVOID THE USE OF ELEVATION ANGLES NEAR 90 OR 270      ]
 ]DEGREES.  IF SUCH AN ELEVATION ANGLE IS USED AND THE "TGT EL ANG"    ]
 ]ALARM IS ANNUNCIATED, CHECK THE MAGNITUDES OF DX AND DY ON THE       ]
 ]ORBIT TARGETING DISPLAY.  IF DY IS LARGER THAN DX, THEN ENTER THE    ]
 ]EXPECTED NOMINAL T1 TIG TIME (ITEMS 2-5), ZERO THE ELEVATION ANGLE   ]
 ](ITEM 6), PERFORM AN ORBIT TARGETING LOAD (ITEM 26), AND REPEAT THE  ]
 ]COMPUTE T1 (ITEM 28).  IF DY IS NOT LARGER THAN DX, THEN FOLLOW      ]
 ]EXISTING PROCEDURES FOR RESPONSE TO A "TGT EL ANG" ALARM.            ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
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