HONOLULU (HawaiiNewsNow) – The wreckage of an air ambulance plane that crashed off Maui last month with three people onboard was found off Maui earlier this week at a depth of more than 6,400 feet, the NTSB said.

Officials said the majority of the wreckage and remains of those killed were recovered Tuesday.

The Hawaii Life Flight twin-engine plane crashed Dec. 15, killing a pilot, flight paramedic and flight nurse. A preliminary report indicates the pilot may have become disoriented and lost control of the aircraft.

Experts: NTSB probe into air ambulance crash indicates pilot was disoriented

“The cockpit voice recorder, cockpit image recorder, and GPS with its navigation data. All of these will play a part in coming up with a complete picture of what happened from the time he took off from Maui to time of impact.”

The city says the bodies are being transported to Oahu and are expected to arrive Friday morning for formal identification by the Honolulu Medical Examiner. Families earlier identified the crew as pilot Brian Treptow, flight nurse Courtney Parry and flight paramedic Gabriel Camacho.

Radar data, radio communications and eyewitness accounts indicate the plane was in the middle of turning when it spiraled into the sea.

“Was their attitude indicator functioning? Might the control surfaces have been compromised to some extent? Were both engines operating?” said Mike Plowman, retired naval aviator and accident investigator.

“There’s enough different types of things such as disorientation control, malfunctions, potential loss of an engine, and potentially reacting incorrectly to a loss of an engine that could put the plane in an out of control flight.”

Following the crash, the Coast Guard searched by air and sea for the plane, but found nothing.

The search effort started Sunday, and involved high-tech underwater sonar systems and autonomous underwater vehicles. Crews searched a 54-square-mile area with ocean depths ranging from 4,500 to 7,500 feet.

Early Monday, the wreckage field was located at a depth of about 6,420 feet, the NTSB said.

Officials said the wreckage was about 1,200 feet south of the last data point received from the aircraft.

The investigation is expected to take at least a year.