Two US Army Apache helicopters collide mid-air during training mission in Alaska.

Three soldiers killed and one injured in the crash

4 on borad

3 killed

1 injured

Army orders 24-hour service-wide stand down to focus on safety

Army investigating training procedures to prevent future crashe

Army experiencing an increase in serious aviation mishaps

Military services report increased aviation mishaps in the last two year

Tough questions being asked about Army's recent mishaps.

ABC News reports on Army helicopter crash and safety concern