SUBJ: GPS STATUS 4 APR 90
1. SATELLITES, PLANES AND CLOCKS (CS=CESIUM RB=RUBIDIUM):
SLOTS MAY NOT BE FINAL UNTIL AFTER 21-SATELLITE REPHASING
A. BLOCK I : PRNS  3,  6,  9, 11, 12, 13
   PLANE   : SLOT D1, A3, A2, C2, A1, C1
   CLOCK   :      RB, RB, RB, CS, CS, CS
B. BLOCK II: PRNS  2, 14, 16, 17, 18, 19, 20
   PLANE   : SLOT B2, E1, D2, F2, F3, A4, TBD
   CLOCK   :      CS, CS, RB, CS, CS, CS, TBD
2. CURRENT ADVISORIES (ADV) AND FORECASTS (FCST):
INFORMATION IS REPEATED FOR SEVEN DAYS AFTER EVENT CONCLUDES
NANU      MSG DATE/TIME   PRN    TYPE  SUMMARY
038-90052 221705Z FEB 90  PRN8   ADV   L-BANDS ENABLED 51/1615
050-90079 191629Z MAR 90  ALLSV  FCST  REPHASING PLAN
055-90087 291643Z MAR 90  PRN9   ADV   UNUSABLE 87/1055 UFN
056-90088 291650Z MAR 90  PRN13  ADV   UNUSABLE 88/0142-88/1105
057-90088 300004Z MAR 90  BLKII  ADV   SPS ACCURACY LEVEL
057-90089 300500Z MAR 90  PRN12  ADV   UNUSABLE 89/0200-0240
058-90090 310144Z MAR 90  PRN9   ADV   USABLE 90/0045
059-90090 312300Z MAR 90  PRN3   ADV   UNUSABLE 90/2204-2215
060-90092 021700Z MAR 90  PRN12  ADV   UNUSABLE 92/1954-92/2005
061-90093 030400Z MAR 90  PRN13  ADV   UNUSABLE 93/0812-93/0824
062-90093 031351Z MAR 90  PRN18  FCST  CHANGE REPHASING TO 6 APR
062-90093 031830Z MAR 90  PRN6   ADV   UNUSABLE 93/1500-93/1530
3. REMARKS:
A. THE CURRENT GPS CONSTELLATION BEGAN BROADCASTING NAVIGATION
MESSAGES AT ACCURACY LEVELS CONSISTENT WITH STANDARD POSITIONING
SERVICE ON 25 MAR 90. GPS IS NOT EXPECTED TO BE DECLARED FULLY
OPERATIONAL UNTIL 1993. ANY GPS USERS ARE OPERATING AT THEIR OWN
RISK.
4. SATELLITE REPOSITIONING:
PRN  INITIATE  TERMINATE#1 TERMINATE#2 UNUSABLE (DAY/UTC)
11   15 MAR 90 31 OCT 90                74/0335-75/0225   ACTUAL
 3   20 MAR 90 17 OCT 90                79/0700-79/1220   ACTUAL
13   29 MAR 90  3 OCT 90                88/0142-88/1105   ACTUAL
18    6 APR 90 24 NOV 90   8 DEC 90     96/1207-97/1207   FORECAST
19   12 APR 90 31 DEC 90               102/0938-103/0938  FORECAST
 9   19 APR 90 19 APR 90               109/0928-110/0928  FORECAST
16   26 APR 90 20 SEP 90               116/1317-117/1317  FORECAST
 2    3 MAY 90  1 DEC 90               TBD
14   13 MAY 90 10 NOV 90               TBD
12   20 MAY 90 20 MAY 90               TBD
5. (almanac deleted)
PRN20 ALMANAC IS AVAILABLE IN THE NAVIGATION BROADCAST.
6. POINT OF CONTACT: MAJ FAUVER AT (719)550-6379