The union representing more than 5,000 staff at the United Nations’ headquarters is calling for a review of that organization’s helicopter operations and “a full account of the causes” of its latest crash, according to The Associated Press. The March 3 crash of a Mi-8 in a mountainous area east of Katmandu, Nepal killed seven U.N. staff members and the helicopter's three-man crew. The union wants an examination of how the U.N. contracts for aircraft and its policies on air safety to determine whether they “are adequate or sufficiently monitored,” the AP said. The union said 10 fatal crashes involving U.N. or U.N.-contracted helicopters since 1997 have killed at least 90 people. The worst crash, in Sierra Leone in June 2004, killed 24 peacekeepers and other personnel. The union wants results of all previous crash investigations made public.