US Army halts aviation operations after fatal helicopter crashes.

The US Army has ordered an aviation stand-down after two fatal helicopter crashes, the most recent of which killed three soldiers and injured a fourth in Alaska on Thursday. The order by Army Chief of Staff James McConville grounds all Army aviators except those on critical missions until they do training. Twelve soldiers have been killed in helicopter crashes since March. The Army will review "risk approval/risk management process," aircraft maintenance training, how flight briefings are done and flight planning, aimed at reducing risks, among other issues.