 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] DR:              ]
 ] C. FLETCHER        ]    PASS PROGRAM NOTE        ]     57376        ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE: 1/3/85     ]
 ] IBM/282-7333       ]      RELEASE NOTE( )        ]                  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ] OI05 AND SUBS                 ]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW ( )  GNC (X)  VU ( )  SM/PL ( )]       G2, G8                    ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: ORBIT, NAV, DAP, ADI                             ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: 4.35, 4.97, 4.126, 4.169, 4.213                ]
 ]_____________________________________________________________________]
 ] TITLE:    STALE STATE VECTOR AFTER ORBIT OPS TRANSITION             ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:     ON-ORBIT NAVIGATION DOES NOT EXECUTE AND COMPUTE   ]
 ] THE ORBITER STATE VECTOR UNTIL BETWEEN FOUR AND SEVEN SECONDS AFTER ]
 ] COMPLETION OF AN OPS MODE RECALL WITH TARGET SET CHANGE OR AN OPS   ]
 ] TRANSITION.  DURING THIS PERIOD, THE M50 TO LVLH TRANSFORMATION     ]
 ] QUATERNION WILL BE STALE AND WILL CAUSE THE FOLLOWING ANOMALOUS     ]
 ] BEHAVIORS:                                                          ]
 ]                                                                     ]
 ]    A) THE ATTITUDE DISPLAYED ON ANY ADI FOR WHICH THE LVLH REFERENCE]
 ]       IS SELECTED WILL BE INCORRECT UNTIL THE STATE VECTOR IS       ]
 ]       RECOMPUTED.                                                   ]
 ]                                                                     ]
 ]    B) IF THE DAP MANUAL LVLH MODE IS INITIALIZED AFTER THE TRANS-   ]
 ]       ITION OR RECALL AND BEFORE NAVIGATION RUNS, THE COMMANDED     ]
 ]       LVLH ATTITUDE WILL BE BASED UPON A STALE STATE VECTOR.  IF    ]
 ]       NAVIGATION WAS INACTIVE LONG ENOUGH DURING THE TRANSITION     ]
 ]       OR RECALL, AND THE ORBITER RATES WERE HIGH ENOUGH, A MANEUVER ]
 ]       COULD RESULT AFTER NAVIGATION IS RE-ACTIVATED.                ]
 ]                                                                     ]
 ]    C) IF THE DAP MANUAL LVLH MODE OR A UNIVERSAL POINTING EARTH-    ]
 ]       RELATIVE OR CENTER-OF-EARTH TRACK OPTION IS ACTIVATED PRIOR TO]
 ]       THE TRANSITION OR RECALL, THE DAP WILL OPERATE ON AN ATTITUDE ]
 ]       ERROR BASED IN PART ON STALE DATA.  THIS COULD RESULT IN      ]
 ]       TRANSIENT JET FIRINGS UNTIL THE STATE VECTOR IS UPDATED.      ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]IBM: WYATT COOPER         DATE 7/28/88 ]                             ]
 ]    --------------------      ---------]                             ]
 ]SSD: SAM ANKNEY           DATE 7/28/88 ]                             ]
 ]    --------------------      ---------] RW MOOREHEAD        7/30/88 ]
 ]PF MGR: KL LINDSAY        DATE 7/29/88 ]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
 @
 +_____________________________________________________________________
 ]                                                                     ]
 ]                       SUPPLEMENTAL SHEET                            ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] AUTHOR:            ]                             ] DR:              ]
 ]  T.P. MALONEY      ]    PASS PROGRAM NOTE        ]     57376        ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE: 1/3/85     ]
 ]  IBM/333-7429      ]      RELEASE NOTE( )        ]                  ]
 ]____________________]_____________________________]__________________]
 ] TITLE:    STALE STATE VECTOR AFTER ORBIT OPS TRANSITION             ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ]    A)  BE AWARE OF THE ABOVE.                                       ]
 ]    B)  AVOID THE LVLH MODE PBI DURING THE TRANSITION OR RECALL AND  ]
 ]        FOR SEVEN SECONDS AFTER RESUMPTION OF GN AND C PROCESSING TO ]
 ]        PRECLUDE THIS RCS ACTIVITY.  OTHERWISE BE AWARE OF THE ABOVE.]
 ]    C)  BE AWARE OF THE ABOVE.                                       ]
 ]                                                                     ]
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 ]                                                                     ]
 ]_____________________________________________________________________]
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