It has been reported that the aircraft hit high ground approximately 15 km to the north-west of the airport, near the village of Kadjedje. The entire instrument approach procedure lies to the southwest of the airport.
The crew were familiar with the area, which suggests that they would not have intentionally descended below the known high ground until they knew with certainty that they had reached the lake, or were abeam the airport.
The accident appears to have happened in the enroute phase of flight, or during the initial descent from cruise altitude, not during maneuvering for approach.
Something is odd here. Are South African registered 19 seaters obliged to be equipped with Class A TAWS? Are they obliged to be equipped with contemporary GPS receivers, installed in accordance with a TSO (as opposed to a Garmin handheld sitting on the glareshield or clipped to the yoke)? If so, were these systems functioning properly in this aircraft?
For the record, here is the publicly advertised flight schedule:
Air Serv Scheduled Flights
Here is a link to a MONUC (UN Mission in DRC) press release that provides additional details about the passenger manifest:
MONUC Press Release