After the withdrawal of its Aerospatiale SA330 Puma helicopters, the Air Support Unit of the Rijkswacht/Gendarmerie (now Federale Politie/Police Federale) had a requirement for a twin-engined medium sized helicopter (twin-engined as the aircraft should also be able to operate safely urban areas). The aircraft had to be equipped with special observation equipment and cleared for night operations.
The aircraft selected was the McDonnell Douglas MD900 Explorer equipped with a NOTAR or 'NO TAil Rotor' system. The NOTAR replaces the classic rear propellor by an aerodynamic system in which air pressure is guided through the tail-boom to a nozzle which can guide the helicopter in the desired direction. One of the added bonuses of the system is that the NOTAR equipped machines are very silent. In 1997 two Explorers joined the then Rijkswacht/Gendarmerie followd by two more machine in 2001 en 2010.