Accident
On a night approach to Ndola, a four-engine aircraft operating as United Nations special flight UNO001 from Léopoldville descended too low and struck trees. The airplane crashed in flames in a wooded area 15 kilometers short of the runway. The aircraft was totally destroyed. All five crew members and 11 passengers, including United Nations Secretary-General Dag Hammarskjöld, were killed.
Investigation
The investigation commission concluded that the aircraft was allowed by the pilots to descend too low, causing it to strike trees and crash. The commission noted that it could not determine whether the low descent resulted from inattention to altimeters or misreading them. The commission also considered other possible causes, including sabotage, attack, material failure, and human failure, but found no evidence to support any particular theory. The United Nations commented that the commission examined all possible causes and could not exclude any of them, noting that sabotage or attack could not be ruled out. Technical experts examined the wreckage but found no evidence of material failure, though extensive fire damage limited the examination. The commission also found no evidence that any pilot was incapacitated, though some forms of incapacity might not be detectable post-mortem. The possibility of pilot error, such as using a wrong instrument approach chart or misreading altimeters, was considered but not indicated as probable cause. The commission reported that it examined various rumors concerning the crash but found no evidence to support them.
Probable Cause
Aircraft was allowed, by the pilots, to descend too low, causing it to strike trees and crash.