The investigation revealed that ATC cleared the flight to "the VOR approach", without actually specifying which specific VOR approach procedure was to be used, possibly leaving it to the flight crew's discretion. According to the radio communication transcript, the flight crew did not inquire as to which specific approach was in effect. There were two published VOR approaches at the time, one from the north and one from the south. The northern approach, called "VOR/DME 19", was not legally available to the crew under these circumstances, as Mohawk company policy prohibited reliance on DME as a primary navigational instrument. The other VOR approach, called "VOR 1", was the only one legally available to the flight, and would have required descending while approaching the airport from the south during the final approach segment, followed by a "circle to land" maneuver, landing to the south on runway 19.