Plagued by a series of helicopter and jet crashes in recent months, the Navy said Friday it will ground all its aircraft for half a day next week for an internal safety review.

The safety stand down will affect 3,800 aircraft and thousands of naval aviation personnel, including aircraft on 12 carriers around the world. It is the first time since September 1997 that such a pause in flight operations across the Navy has been ordered.

Grounding the flights is not related to any specific equipment or flying problem, the Navy said, but rather is a way to refocus on safety, risk management and other procedures.

Since Oct. 1, there have been nine major crashes that resulted in loss or life or of the aircraft. Nine aircraft were destroyed and 10 naval aviators were killed. During the same period a year ago, there were eight major crashes.

All naval aviation squadrons will be required to complete the safety review by the end of next week, but no particular day is being designated.

The most recent accident occurred Friday when a Navy jet crashed in the remote northeastern corner of Oregon. The pilot was rescued after ejecting. In early February, another Navy pilot was rescued after his F/A-18 Hornet jet crashed into the water near Key West. And in late January, a Navy pilot and his student were killed when their training plane crashed just south of Naval Air Station Corpus Christi in Texas.