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 ] AUTHOR:            ]                             ] DR:              ]
 ] V. SHAH            ]    PASS PROGRAM NOTE        ]       108662     ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:  03/24/92  ]
 ] LSIS/282-7218      ]      RELEASE NOTE( )        ] REV A: 01/11/95  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ] OI-20 AND SUBS                ]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW ( )  GNC (X)  VU ( )  SM/PL ( )] G3                              ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: ENTRY, GUID, ADI                                 ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: 4.8                                            ]
 ]_____________________________________________________________________]
 ] TITLE:                                                              ]
 ]        ENTRY ROLL COMMAND SIGN REVERSAL                             ]
 ]_____________________________________________________________________]
 ] DESCRIPTION: IN MM 304:                                             ]
 ] THE COMMANDED ROLL ANGLE CAN BUILD UP TO 180 DEGREES:               ]
 ]  1) IN THE ENTRY CSS MODE, IF THE INITIAL MANUAL ROLL MANEUVER IS   ]
 ]     DELAYED (25-30 SECONDS)                                         ]
 ]  2) DURING THE INITIAL PULLOUT OF A HIGH INCLINATION INTACT TAL     ]
 ]     FOR SOME DISPERSED CONDITIONS                                   ]
 ]  3) IN OFF NOMINAL ENTRY CONDITIONS                                 ]
 ] IN THESE CASES, THE DIRECTION OF THE ROLL COMMAND (ROLLC(1)) ON THE ]
 ] ADI ERROR NEEDLES CAN CHANGE SIGN.  THAT IS, IF A LEFT ROLL IS      ]
 ] DESIRED, THE COMMAND WILL CHANGE TO RIGHT AT 180 DEGREES.  THIS IS  ]
 ] BECAUSE OF INACCURACIES IN THE INTERNAL GPC PRECISION OF PI IN      ]
 ] SOME OF THE HAL/S TRIG FUNCTIONS USED IN ENTRY GUIDANCE.  ROLLC(1)  ]
 ] IS ALSO DISPLAYED ON THE ENTRY TRAJ DISPLAY (ROLL COMMAND) AND IS   ]
 ] DOWNLISTED(V90H1044C).                                              ]
 ]                                                                     ]
 ] THIS TYPE OF PROBLEM COULD ALSO OCCUR WITH ROLL REF ANGLE (ROLLC(3))]
 ] IF THE RATIO OF LIFT/DRAG REFERENCE TO CURRENT L/D IS LESS THAN OR  ]
 ] EQUAL TO -1.0.  ROLLC(3) IS DISPLAYED ON ENTRY TRAJ DISPLAY         ]
 ] (ROLL REF) AND IS DOWNLISTED(V90H1142C).                            ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ] FOR A ROLL STEERING COMAND IN THE VICINITY OF 180 DEGREES, THE CREW ]
 ] SHOULD IGNORE ROLL DIRECTION REVERSALS COMMANDED BY THE ADI NEEDLES ]
 ] AND VERIFY CORRECT DIRECTION OF ROLL WITH THE RUNWAY LOCATION ON THE]
 ] HSI.  SIGN CHANGES IN ROLL REF AND ROLL CMD ON THE ENTRY TRAJ       ]
 ] DISPLAY AND DOWNLISTED DATA (V90H1142C AND V90H1044C) SHOULD ALSO   ]
 ] BE IGNORED.                                                         ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]LSIS:  JEAN L. ZOPHY      DATE 02/14/95]                             ]
 ]     -------------------      ---------]                             ]
 ]ASD:   ERIC C. BINGHAM    DATE 02/14/95]                             ]
 ]     -------------------      ---------] DARRELL E. STAMPER 02/16/95 ]
 ]PF MGR: J'ANN H. SIDERS   DATE 02/16/95]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
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