Air Serv International, the Warrenton, Va.-based aid group that runs the twice-weekly aid delivery between Kisangani and Bukavu, said helicopter surveys suggested everyone on board was killed.
"According to the information in our possession, there were no survivors," Amy Cathey, a manager for Air Serv in the regional capital, Goma, told Congo's U.N.-funded radio station.
The 21-seat Beechcraft 1900 aircraft went missing late Monday with two crew and 15 passengers, a spokeswoman for the U.N. Office for the Coordination of Humanitarian Affairs said. It was found Tuesday morning, Elisabeth Byrs told journalists in Geneva.
In New York, U.N. deputy spokeswoman Marie Okabe said the plane "apparently crashed into a mountain ... northeast of Bukavu Airport while beginning its landing approach in bad weather."
She said the cause of the crash was under investigation. U.N.
peacekeepers who surveyed the site by helicopter were unable to land "due to the difficult terrain," she said.
U.N. Secretary-General Ban Ki-moon's "thoughts are with the families and colleagues of those United Nations and NGO aid workers, Congolese officials and crew who were on board the aircraft," Okabe said.
Officials at Air Serv said late Tuesday that heavy fog prevented the search team from reaching the crash site.
"We tried by every means, but the weather conditions didn't allow us to land," said Fernand Kabemba, one of Air Serv's agents in the eastern Congo town of Goma.
The identities of the passengers has not been disclosed, but Kabemba he said that they included Canadian, French and Indian nationals.
Air Serv International describes itself as a not-for-profit aviation organization that supports humanitarian programs worldwide.
No Air Serv personnel were involved in the crash, spokeswoman Suzanne Musgrave told The Associated Press by telephone from Warrenton.
She said the plane was being flown by a South African commercial company, Cem Air.
Cem Air confirmed that the crash involved one of its planes and that two of its crew were on board.
Congo has experienced more fatal crashes since 1945 than any other African country, according to the nonprofit Aviation Safety Network.
Most recently, a DC-9 operated by the private Congolese company Hewa Bora Airways rammed into a bustling market after failing to lift off from Goma's airport on April 15, killing at least 40 people, most of them on the ground. On Oct. 4, a turboprop cargo plane belonging to the Congolese company Africa One slammed into an impoverished residential neighborhood in Congo's capital of Kinshasa after takeoff, leaving at least 25 people dead.
