The final weather report sent to the aircraft accurately stated that there was visibility of 900 meters in dense fog, 1/4 cloud cover with a cloud base at 400 feet, and winds calm. This surprised the flight crew, because previous weather information had given visibility of 6 kilometers. As a result, despite the fact that the aircraft was cleared for a VOR/DME (VHF omnidirectional range/Distance Measuring Equipment) approach, it was an ILS/DME (Instrument Landing System/Distance Measuring Equipment) that was initiated. ILS navigational equipment is normally more accurate than VOR/DME equipment, but in this case the ILS equipment at Zanderij airport, though transmitting signals, was not suitable nor available for operational use. The investigation showed that the crewmembers were aware of this. The cockpit voice recorder captured the first officer saying, "I don't trust that ILS", but the captain chose to use it regardless. He did instruct the First Officer to tune the required navigational equipment for the functional VOR/DME approach, most likely for use as a gross error check.