A deep-water search operation has recovered the three-­member flight crew and wreckage of a Hawaii Life Flight medical transport plane that crashed into the ocean Dec. 15 off Maui near Kaupo, according to the National Transportation Safety Board.

The cockpit voice recorder, cockpit image recorder and other electronic components were retrieved from the wreckage of the Raytheon Aircraft Co. C90A twin-engine, turbine-­powered airplane and will be transported to the NTSB laboratory in Washington, D.C., as part of the accident investigation, which is expected to be completed in 12 to 24 months, the agency said Wednesday.

Pilot Brian Treptow, flight nurse Courtney Parry and flight paramedic Gabriel Camacho were killed when the plane spiraled into the ocean after departing Kahului Airport to pick up a patient at the Waimea-Kohala Airport on Hawaii island.

Their families were notified of the recovery, according to Honolulu Mayor Rick Blangiardi’s office. The remains of the three crew members were removed from the plane wreckage at around 1:45 p.m. Tuesday after it was brought to the surface, the office said. The remains are being transported to Oahu on a private vessel and were expected to arrive this morning, when they will be transferred to the Honolulu Department of the Medical Examiner.

Hawaii Life Flight officials declined to comment Wednesday on the recovery of the aircraft wreckage and crew.

Guardian Flight, parent company of Hawaii Life Flight, was contracted to conduct the search operation, according to the NTSB. The search vessel MV Island Pride, operated by Ocean Infinity, arrived off Oahu on Saturday. On board the vessel when the search began Sunday were the NTSB investigator-­in-charge, the chief of the NTSB Office of Transportation Disaster Assistance, Guardian Flight’s director of safety, “and a project manager that has prior experience with over-water loss recoveries,” the NTSB said.

The 340-foot MV Island Pride, which is equipped with a helicopter deck, is used for large-scale seabed surveys and other purposes, according to the Ocean Infinity website. The ship’s side-scan and multibeam sonar, autonomous underwater drones and a remotely operated vehicle were deployed to search for the downed aircraft, the NTSB said.

The search area covered about 54 square miles at depths ranging from 4,500 to 7,500 feet. After the vessel’s acoustic positioning system detected a series of pings from the acoustic beacon installed on the plane’s cockpit voice recorder, the wreckage was located at about 5:30 a.m. Monday at a depth of about 6,420 feet, about 1,200 feet south from where it was last tracked, according to the NTSB.

After additional surveys by the remotely operated vehicle, the flight crew and “the majority of the wreckage” were recovered Tuesday, the NTSB said. The wreckage was being transported to a secure location in Hawaii for further examination.

The NTSB’s Jan. 5 preliminary report on the crash said the Hawaii Life Flight aircraft departed from Kahului Airport at 8:53 p.m. Dec. 15 and headed east-southeast along Maui’s northern coastline before turning south along a predetermined flight route, the report noted. Air traffic controllers were in regular contact with the pilot, and about 20 minutes into the flight Treptow was instructed to fly directly to a fixed navigation point for the initial approach to Waimea-Kohala Airport.

At 9:13 p.m., when the controller tried to confirm he was flying as directed, Treptow replied, in part, referring to the plane’s registration number, “Uh, 13GZ is off navigation here. … We’re gonna … we’re gonna give it a try.”

The controller contacted the pilot again about the plane’s heading and maintaining altitude at 8,000 feet, the report said, but 11 seconds later came Treptow’s final radio transmission, “Hang on.”

An alert about the missing plane was issued by the Federal Aviation Administration at 9:27 p.m. and an extensive search was launched by the U.S. Coast Guard, with portions of wreckage found floating near the flight’s last known location. The search was suspended Dec. 19.

The pilot of a small plane flying in the area at the time reported seeing the Hawaii Life Flight aircraft start to bank right and then enter “a spiraling right descending turn, which steepened as the descent increased,” according to the NTSB preliminary report. The pilot told investigators he watched the aircraft continue its plunge until it hit the water and he lost sight of its lights.

Hawaii Life Flight resumed medical transport services last week after “taking a deliberate pause in service to perform precautionary maintenance checks and to focus on the mental well-being of our crew members,” according a Jan. 4 company statement.