The aerial survey team consisted of 4 people: the pilot David Moyer, a front-seat observer Hilde Vanleeuwe and 2 back-seat observers, Cyril Pélissier and Philipp Henschel. Philipp was replaced by Arnaud Gotanègre the last day. Mr Richard de Cauwer, General Director of Congo Safaris kindly offered the team to stay at his camp at Kiubo falls (Fig 1).
Transects of 10km interval were flown over UNP and KNP with a Cessna 182 aircraft and all signs of human presence and animal presence were recorded. The plane flew at 400 feet to optimize the probability of observing everything within a 500 meter strip-width on both sides of the plane. The backseat observers each focus on their side of the plane, demand a waypoint to the front-seat observer for each observation and they speak the waypoint and associated observation into a tape recorder. The front-seat observer provides waypoints to the back-seat observers and takes georeferenced digital pictures. Every evening, pictures, flight-lines, waypoints and tape-recorded observations were entered onto Excel.