NOTICE ADVISORY TO NAVSTAR USERS (NANU) #056-90088
SUBJ: PRN13 WAS UNUSABLE BEGINNING 29 MAR 90 (DAY 88) AT
0142 UTC UNTIL DAY 88/0142-88/1105 UTC
1. CONDITION: PRN13 WAS UNUSABLE BEGINNING 29 MAR 90 (DAY 88) AT
0142 UTC UNTIL DAY 88 ENDING 1105UTC. THIS OUTAGE IS THE RESULT OF
THE INITIATION OF REPHASING, NO OUTHER OUTAGE TO PRN13 AS A RESULT OF
REPHASING IS EXPECTED UNTIL 3 OCT 90 (DAY 276).
A. PRN 18 IS THE NEXT SATELLITE SCHEDULED TO BEGIN REPHASING ON
7 APR 90 (DAY 97) AND WILL BE SET UNUSABLE AT APPROXIMATELY
1207 UTC.
B. THE REPHASING SCHEDULE FOR 1990 FOLLOWS:
PRN   INITIATE    TERMINATE#1     TERMINATE#2     UNUSABLE (DAY/UTC)
11    15 MAR 90     31 OCT 90                      74/0335-75/0225
 3    20 MAR 90     17 OCT 90                      79/0700-79/1220
13    29 MAR 90      3 OCT 90                      88/0142-88/1105
18     7 APR 90     24 NOV 90       8 DEC 90       97/1207-98/1207
19    12 APR 90     31 DEC 90                     102/0938-102/0938
 9    19 APR 90     19 APR 90                     109/0928-109/0928
16    26 APR 90     20 SEP 90                     116/1317-116/1317
 2     3 MAY 90      1 DEC 90                     TBD
14    13 MAY 90     10 NOV 90                     TBD
12    20 MAY 90     20 MAY 90                     TBD
3. RECOMMENDATION: GPS USERS SHOULD UPDATE ALMANACS FOR PRN13.
4. POINT OF CONTACT: MAJ WILLIAM FAUVER AT COMMERCIAL (719)550-6379
OR AUTOVON 560-6379.