NOTICE ADVISORY TO NAVSTAR USERS (NANU) #033-91033
SUBJ: PRN6 UNUSABLE DAY 33 0815-1000 UTC
1. CONDITION ON DAY 33 (2 FEB 91):
A. PRN9 (MCS: SVN6) WILL BE SET USABLE IN ALMANAC AND EPHEMERIS
HEALTH ON DAY 33. AFTER PRN9 IS USABLE THERE WILL BE TWO TWO-HOUR
PERIODS EACH 24-HOURS WHEN L-BAND IS TURNED ON. THESE PERIODS
COINCIDE WITH TIMES WHEN THE SATELLITE'S ANTENNAS ARE POINTING
TOWARD THE EARTH AS A RESULT OF SPIN STABILIZATION. THE SPIN AXIS
OF PRN9 IS POINTING AT THE EARTH'S CENTER THROUGH THE PERSIAN GULF
AREA (PGA) DURING ONE OF THE L-BAND-ON PERIODS AND THROUGH WESTERN
NORTH AMERICA (WNA) DURING THE OTHER PERIOD. AT OTHER TIMES OR LOCATIONS
PRN9 MAY NOT BE USABLE. L-BAND-ON FORECAST FOR THE NEXT SEVEN DAYS:
DAY DATE      L-BAND-ON WNA   L-BAND-ON PGA
33  02 FEB 91                 33/1809-33/2024
34  03 FEB 91 34/0550-34/0750 34/1805-34/2020
35  04 FEB 91 35/0546-35/0746 35/1801-35/2016
36  05 FEB 91 36/0542-36/0742 36/1757-36/2012
37  06 FEB 91 37/0538-37/0738 37/1743-37/2008
38  07 FEB 91 38/0534-38/0734 38/1739-38/2004
39  08 FEB 91 39/0530-39/0730 39/1735-39/2000
B. PRN6 (MCS: SVN3) WAS UNUSABLE ON DAY 33 BEGINNING 0815 UTC UNTIL DAY
33 AT 1000 UTC. THE L-BAND OF PRN6 WILL BE DISABLED AS BELOW:
DAY DATE      UNUSABLE (UTC)  ACTUAL (UTC)
33  02 FEB 91 33/0815-33/1000 33/0815-33/1000
34  03 FEB 91 34/0815-34/1000
35  04 FEB 91 35/0815-35/1000
2. RECOMMENDATION: PRN6 WILL BE UNUSABLE FOR NAVIGATION OR
POSITIONING DURING THESE OUTAGES. CONFIRM AVAILABILITY OF
SATELLITES PRIOR TO USE.
3. POINT OF CONTACT: MAJ WILLIAM FAUVER AT COMMERCIAL
(719)550-6379OR AUTOVON 560-6379.