Narrative:

I was traveling southwest on V433 at 10500 ft VFR in my small aircraft. Smooth air, clear of clouds, almost no traffic reported by center. Upon crossing chesapeake bay, I noticed my storm scope displaying heavy electrical activity, not consistent with airborne electrical discharges (thunderstorms), but identical to the display seen upon taxiing over buried power lines. The display was unaffected by range change. As I passed over the bay, the display moved from my 12 O'clock position, gradually to the 3 O'clock and then the 6 O'clock position. At about XY10 local, the display cleared. More importantly, my LORAN lost all stations. Not just the signal degraded, but complete station loss. Attempting to display stations yielded 0-0. It was blown off the air! The LORAN did not begin acquisition of signal until the bay was crossed and the storm scope ceased to display. As an additional observation, united states navy warships were in the bay. If, as was suggested, war games were using passing civilian craft, the action is a hazard to navigation and safety! Callback conversation with reporter revealed the following: reporter was questioned reference his statement of navy 'using civilian aircraft.' he feels there was a lot of 'juice' coming at him and possibly a high power radar beam. The storm scope only responds to electrical activity and there was only clear sky, so he feels navy activity was the major problem. The position of the electrical activity moved from 12 O'clock to 3 O'clock then to 6 O'clock as he crossed the bay so it was from a fixed position. He knows of others who have experienced similar navigation problems when navy is active. The worst part for him was total of the LORAN. His is high priced, well made equipment that gives him no problems. As soon as he was over land, the equipment began to function properly.

Related reports:

Google
 

Original NASA ASRS Text

Title: SMA HAS SEVERE ELECTRICAL INTERFERENCE PROB. LOSS OF LORAN AND STORM SCOPE UNUSUAL ACTIVITY.

Narrative: I WAS TRAVELING SW ON V433 AT 10500 FT VFR IN MY SMA. SMOOTH AIR, CLR OF CLOUDS, ALMOST NO TFC RPTED BY CTR. UPON XING CHESAPEAKE BAY, I NOTICED MY STORM SCOPE DISPLAYING HVY ELECTRICAL ACTIVITY, NOT CONSISTENT WITH AIRBORNE ELECTRICAL DISCHARGES (TSTMS), BUT IDENTICAL TO THE DISPLAY SEEN UPON TAXIING OVER BURIED PWR LINES. THE DISPLAY WAS UNAFFECTED BY RANGE CHANGE. AS I PASSED OVER THE BAY, THE DISPLAY MOVED FROM MY 12 O'CLOCK POS, GRADUALLY TO THE 3 O'CLOCK AND THEN THE 6 O'CLOCK POS. AT ABOUT XY10 LCL, THE DISPLAY CLRED. MORE IMPORTANTLY, MY LORAN LOST ALL STATIONS. NOT JUST THE SIGNAL DEGRADED, BUT COMPLETE STATION LOSS. ATTEMPTING TO DISPLAY STATIONS YIELDED 0-0. IT WAS BLOWN OFF THE AIR! THE LORAN DID NOT BEGIN ACQUISITION OF SIGNAL UNTIL THE BAY WAS CROSSED AND THE STORM SCOPE CEASED TO DISPLAY. AS AN ADDITIONAL OBSERVATION, UNITED STATES NAVY WARSHIPS WERE IN THE BAY. IF, AS WAS SUGGESTED, WAR GAMES WERE USING PASSING CIVILIAN CRAFT, THE ACTION IS A HAZARD TO NAV AND SAFETY! CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: RPTR WAS QUESTIONED REF HIS STATEMENT OF NAVY 'USING CIVILIAN ACFT.' HE FEELS THERE WAS A LOT OF 'JUICE' COMING AT HIM AND POSSIBLY A HIGH PWR RADAR BEAM. THE STORM SCOPE ONLY RESPONDS TO ELECTRICAL ACTIVITY AND THERE WAS ONLY CLR SKY, SO HE FEELS NAVY ACTIVITY WAS THE MAJOR PROB. THE POS OF THE ELECTRICAL ACTIVITY MOVED FROM 12 O'CLOCK TO 3 O'CLOCK THEN TO 6 O'CLOCK AS HE CROSSED THE BAY SO IT WAS FROM A FIXED POS. HE KNOWS OF OTHERS WHO HAVE EXPERIENCED SIMILAR NAV PROBS WHEN NAVY IS ACTIVE. THE WORST PART FOR HIM WAS TOTAL OF THE LORAN. HIS IS HIGH PRICED, WELL MADE EQUIP THAT GIVES HIM NO PROBS. AS SOON AS HE WAS OVER LAND, THE EQUIP BEGAN TO FUNCTION PROPERLY.

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.