THIS ACCIDENT OCCURRED ON A TELEPHONE CABLE PATRL FLT. THE ACFT WOULD NORMALLY FLY ALONG THE ROUTE OF THE BURIED CABLE AT 200 TO 300 FT AGL. WHEN CONSTRUCTION ACTIVITY WAS SIGHTED THE PLT WOULD FIRST RECORD THE SIGHTING ON A PORTABLE TAPE RECORDER AND THEN CALL THE TELEPHONE COMPANY ON A RADIO/TELEPHONE. THE CONTROL HEAD FOR THE RADIO/TELEPHONE OCCUPIED THE PLACE OF THE REMOVED RIGHT, REAR SEAT. WITNESSES SAID THE ACFT CIRCLED TWICE IN THE VICINITY OF THE ACCIDENT SITE BEFORE THE CRASH. THEY SIAD THERE WERE LOW CLOUDS WITH HAZE BUT GOOD VISIBILITY BELOW THE CLOUDS. THE ACFT IMPACTED IN A SHALLOW LEFT BANK IN A SLIGHTLY NOSE LOW ATTITUDE. A MESSAGE ON A TAPE RECORDER FOUND IN THE WRECKAGE DESCRIBED CONSTRUCTION ACTIVITY NEAR THE CABLE IN AN AREA ONE MI W OF THE ACCIDENT SITE. TELEPHONE COMPANY PERSONNEL SAID THAT THEY DID NOT RECEIVE A REPORT FROM THE PLT.