A PHL TRACON DEP CTLR BELIEVES THAT AN ACR MD80 CAPT WAS OFF COURSE OVER MXE. THE CAPT DISAGREES. POSSIBLE RADAR DISPLAY OR EQUIP PROB. POSSIBLE NAVAID PROB OR SITE CHARACTERISTIC. POSSIBLE RF INTERFERENCE FROM ILLEGALLY OPERATED PAX COM OR GAME DEVICES.

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ON DEP FROM PHL; MAINTAINING 10000 FT; CLRED DIRECT TO MXE; THEN MXE 278 DEG RADIAL/48. WHILE APCHING MXE FROM THE NE AND JUST COMMENCING A TURN TO FLY OUT THE 278 DEG RADIAL; THE CTLR QUESTIONED OUR POS. I TOLD HIM OVER MXE TURNING OUT THE 278 DEG RADIAL. HE STATED THAT WE WERE 7 MI S OF MXE. THIS WAS NOT REFLECTED BY OUR INSTS. THE CTLR GAVE US A HDG AND LATER A CLB. THERE WERE NO FURTHER DISCREPANCIES WITH THE NAVAIDS DURING THE FLT. I QUESTIONED THE CABIN ATTENDANTS ABOUT ANY ELECTRONIC EQUIP BEING USED BY A PAX AND THEY TOLD ME THEY WERE UNCERTAIN IF ANY WERE IN USE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTING CAPT STATES THAT HE WAS FLYING THE MXE VOR AT THE TIME; NOT OMEGA. HE WAS NOT ABLE TO CHK ON PAX USAGE OF ELECTRONIC DEVICES UNTIL MUCH LATER; SO THIS CHK WAS INCONCLUSIVE. HE WAS 'IN THE CONE OF CONFUSION' AT THE TIME. HE BELIEVES THAT VOR SIGNALS CAN BE INFLUENCED BY OUTSIDE INTERFERENCE OCCASIONALLY. HE DID NOT AGREE WITH THE NOTION THAT HE WAS OFF COURSE.