Active-duty aviators at 11 Army installations across the U.S. will undergo a safety stand down Thursday through Monday, the Army has announced.

U.S. Army Forces Command directed the stand down after the Army suffered three deadly helicopter crashes in 10 days. This is the first FORSCOM-wide stand down of aviation assets in recent memory, said Paul Boyce, a spokesman for Forces Command.

The stand down affects U.S.-based FORSCOM aviation units, including most of the Army's combat aviation brigades, Boyce said. It does not include units in Europe, the Pacific or elsewhere around the world, he said.

The stand down means aviators will not take to the skies.

"My decision to ground our aircraft today is taken with the utmost seriousness," said Gen. Robert "Abe" Abrams, commanding general of FORSCOM, in a statement. "I have a duty to ensure that we are doing all that we can to prevent the loss of life and aviation accidents, and that is why we're standing down to review our procedures and reaffirm our commitment to operating our aircraft safely and effectively."

As part of the stand down, Army aviation leaders in FORSCOM units will:

• Review the flight-mission briefing process with an emphasis on risk mitigation, crew selection, flight planning, crew/flight briefings, debriefings and after-action reviews.

• Review Army aircraft coordination training.

• Review adherence to flight-operations standards and discipline.

• Review, brief and exercise unit pre-accident plans, including key participants on their Army posts.

• Review their unit's aircraft maintenance training, procedures and supervisory responsibilities.

"We cannot allow tragedy to pass unacknowledged," Abrams said. "We must do whatever is needed to make certain that our soldiers are training and operating safely."

Eight aviators have died since Nov. 23 in a string of deadly crashes.

Two were killed when their AH-64 Apache helicopter crashed in South Korea. The incident happened about 6:30 p.m. local time, or 4:30 a.m. Eastern time, on Nov. 23 about 50 miles east of Camp Humphreys.

The pilots, whose names have not been officially released by the Army, were on a routine training mission. They belonged to the 2nd Combat Aviation Brigade.

On the same day, at 5:49 p.m. Central time, four soldiers died when their UH-60 Black Hawk crashed at Fort Hood, Texas. They also were on a routine training mission.

The crew was assigned to 2nd Battalion, 291st Aviation Regiment, First Army Division West. They were:

• Sgt. 1st Class Toby A. Childers, 40, from Hays, Kansas.

• Chief Warrant Officer 3 Stephen B. Cooley, 40, from Cantonment, Florida.

• Sgt. 1st Class Jason M. Smith, 35, from Destrehan, Louisiana.

• Chief Warrant Officer 3 Michael F. Tharp, 40, from Katy, Texas.

Finally, two aviators were killed Wednesday when their Apache crashed during a training exercise near Fort Campbell, Kentucky. The incident happened about 7 p.m. Central time; the soldiers' names have not been released.

All three crashes are still under investigation by the Army Combat Readiness Center.