NOTICE ADVISORY TO NAVSTAR USERS (NANU) #062-90093
SUBJ: UPDATE TO TENTATIVE GPS REPHASING SCHEDULE FOR PRN18
1. CONDITION: PLANNED SATELLITE REPOSITIONING FOR 1990 IS INDICATED
IN PARA 2 BELOW. CHANGES TO THESE PLANS MAY OCCUR WITHOUT NOTICE,
HOWEVER, USERS WILL CONTINUE TO BE NOTIFIED VIA THE NORMAL ADVISORY
MESSAGE (NANU) IMMEDIATELY PRIOR TO EACH EVENT. ACTUAL TIMES OF
OUTAGES WILL BE PROVIDED/UPDATED AS SPECIFIC INFORMATION BECOMES
AVAILABLE. NOTE PRN18 CHANGE TO 6 APR 90.
2. SATELLITE MAY BE UNUSABLE FOR UP TO 24 HOURS FOLLOWING INITIATE
AND TERMINATE TIMES:
   PRN INITIATE  TERMINATE#1 TERMINATE#2 UNUSABLE (DAY/UTC)
A. 11  15 MAR 90 31 OCT 90               74/0335-75/0225   ACTUAL
B.  3  20 MAR 90 17 OCT 90               79/0700-79/1220   ACTUAL
C. 13  29 MAR 90  3 OCT 90               88/0142-88/1105   ACTUAL
D. 18   6 APR 90 24 NOV 90   8 DEC 90    96/1207-97/1207   FORECAST
E. 19  12 APR 90 31 DEC 90               102/0938-103/0938 FORECAST
F.  9  19 APR 90 19 APR 90               109/0928-110/0928 FORECAST
G. 16  26 APR 90 20 SEP 90               116/1317-117/1317 FORECAST
H.  2   3 MAY 90  1 DEC 90               TBD
I. 14  13 MAY 90 10 NOV 90               TBD
J. 12  20 MAY 90 20 MAY 90               TBD
3. RECOMMENDATION: CONFIRM AVAILABILITY OF GPS SATELLITES PRIOR TO
USE.
4. POINT OF CONTACT: MAJ WILLIAM FAUVER AT COMMERCIAL (719)550-6379
OR AUTOVON 560-6379.