Narrative:

While using GPS as primary navigation lost all satellite signals. GPS went into dr. GPS was functioning properly prior to signal loss and after signal reacquisition. There was no velocity deviation or change in position. GPS was functioning properly, no faults were found with the GPS. Satellite signals were lost in an area from about 25 NM west of mkk VOR to about 30 NM north of mkk. Signals were reacquired and GPS returned to normal navigation. Signals were lost in the same area and then returned to normal when out of the area. Callback conversation with reporter revealed the following information: reporter states he was flying a DC10 and when he spoke to ATC they did not seem very concerned. Since they were heading out over the pacific ocean, they were concerned. The loss of navigation lasted about 5-7 mins. This occurred several times and to several other pilots during a 2 1/2 week period. When they were about 50 mi from the island they could see the satellites begin dropping off. Reporter just found out that the military was testing for jamming of satellites. The FAA knew about it but did not issue a NOTAM to alert pilots. The tests were to last about 40 seconds, but that is not what happened.

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Original NASA ASRS Text

Title: FLC OF DC10 HAS LOSS OF SATELLITE NAV WHEN USING GPS AS THE PRIMARY NAV AND STARTING FLT OVER THE OCEAN.

Narrative: WHILE USING GPS AS PRIMARY NAV LOST ALL SATELLITE SIGNALS. GPS WENT INTO DR. GPS WAS FUNCTIONING PROPERLY PRIOR TO SIGNAL LOSS AND AFTER SIGNAL REACQUISITION. THERE WAS NO VELOCITY DEV OR CHANGE IN POS. GPS WAS FUNCTIONING PROPERLY, NO FAULTS WERE FOUND WITH THE GPS. SATELLITE SIGNALS WERE LOST IN AN AREA FROM ABOUT 25 NM W OF MKK VOR TO ABOUT 30 NM N OF MKK. SIGNALS WERE REACQUIRED AND GPS RETURNED TO NORMAL NAV. SIGNALS WERE LOST IN THE SAME AREA AND THEN RETURNED TO NORMAL WHEN OUT OF THE AREA. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES HE WAS FLYING A DC10 AND WHEN HE SPOKE TO ATC THEY DID NOT SEEM VERY CONCERNED. SINCE THEY WERE HDG OUT OVER THE PACIFIC OCEAN, THEY WERE CONCERNED. THE LOSS OF NAV LASTED ABOUT 5-7 MINS. THIS OCCURRED SEVERAL TIMES AND TO SEVERAL OTHER PLTS DURING A 2 1/2 WK PERIOD. WHEN THEY WERE ABOUT 50 MI FROM THE ISLAND THEY COULD SEE THE SATELLITES BEGIN DROPPING OFF. RPTR JUST FOUND OUT THAT THE MIL WAS TESTING FOR JAMMING OF SATELLITES. THE FAA KNEW ABOUT IT BUT DID NOT ISSUE A NOTAM TO ALERT PLTS. THE TESTS WERE TO LAST ABOUT 40 SECONDS, BUT THAT IS NOT WHAT HAPPENED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.