ALTDEV ALT EXCURSION FROM ASSIGNED.

Narrative

ON SEP/FRI/93; ABOUT PM55 LCL TIME; I WAS FLYING SAFETY PLT IN SMA. NEW YORK CTLR GAVE PIC; UNDER THE HOOD AND HANDLING THE RADIO COM; A DSCNT TO 2000 FT; HDG 150 DEGS. SHORTLY AFTER A DIFFERENT VOICE BUT USING STANDARD TERMINOLOGY SAID; 'DSND AND MAINTAIN 1500 FT.' THE PLT COMPLIED AFTER READING IT BACK. SHORTLY AFTER THE CTLR ASKED US WHAT WE WERE DOING AT 1500 FT WHEN WE SHOULD BE AT 2000 FT. I THINK IN RETROSPECT THAT WE RECEIVED AN ILLEGAL XMISSION FROM THE GND. ABOUT 35 MINS AFTER THE INCIDENT I RPTED IT TO THE NEW YORK FACILITY. I DON'T THINK I MENTIONED THAT WE WERE MAKING A PRACTICE ILS 6 AT BDR WHEN THE INCIDENT OCCURRED. AFTER THE FALSE RADIO XMISSION WE DEVIATED ABOUT 500 FT ON OUR ALT AND THEN CLBED BACK TO 2000 FT. I DO NOT THINK THAT THE CTLR HEARD THE ILLEGAL XMISSION AS IT WAS PROBABLY TOO FAR FROM WHERE THE NEAREST GND ANTENNA IS LOCATED. LATER; I WAS CONTACTED AT HOME BY AN FAA REPRESENTATIVE AND GAVE ALL THE DETAILS AS TO THE EXACT LOCATION OF EVENT FOR HIM TO FOLLOW-UP IN HIS VAN WHICH IS EQUIPPED TO DETECT ILLEGAL XMISSIONS ON THE GND.