The worst: In January 2016, 12 Marines were killed when two Super Stallion helicopters collided about two miles off Haleiwa during night training.
It was one of the nation's deadliest crashes involving military aircraft in a training exercise in a decade.
Here's a look at other recent military crashes in the islands:
— On May 17, 2015, two Marines were killed and 20 were injured when an MV-22 Osprey crashed during pre-deployment training. An investigation found the crash was caused by pilot performance and an improper survey of the landing zone.
— On March 19, 2011, one Marine was killed and three others were injured when a CH-53D Sea Stallion helicopter crashed into Kaneohe Bay during a training flight.
— On Feb. 1, 2008, a Hawaii National Guard pilot ejected from an F-15 about 60 miles off Oahu after the aircraft encountered problems. The pilot was not seriously injured.
— On Feb. 13, 2001, six Schofield Barracks soldiers were killed and four were injured when two Black Hawk helicopters collided at the Kahuku Military Training Reservation.