Soldiers from the 25th Combat Aviation Brigade observed a moment of silence Tuesday during a ceremony for Chief Warrant Officer 2 Jonathan Bryce Millward and Chief Warrant Officer 3 Stanley Blane Hepfner, the two pilots killed when their helicopter crashed at Wheeler Army Airfield on May 27.

Four OH-58D Kiowa Warrior helicopters — the same model Millward and Hepfner piloted — flew over the ceremony site in formation. One aircraft then veered off, signifying the loss of the two soldiers.

The Army posthumously promoted Hepfner to Chief Warrant Officer 3. The 29-year-old from of Hubbard, Ohio, had already been selected for the promotion before the accident.

The 28-year-old Millward was from Chubbuck, Idaho.

The cause of the crash is under investigation.