Federal investigators say a cargo plane ditched into the ocean off Hawaii in 2021 because pilots identified the wrong engine that was failing and didn’t have enough power to remain airborne.

The National Transportation Safety Board also said the captain’s high workload as well as poor communication and teamwork between the two pilots contributed to the accident.

The captain was seriously injured, the co-pilot suffered minor injuries, and the plane was destroyed, the NTSB said Thursday. The plane was owned by Rhoades Aviation Inc. and operated as a Transair cargo flight.

The 46-year-old Boeing 737 was scheduled to fly from Honolulu to Kahului, Hawaii, in the predawn hours of July 2, 2021, but wound up in Mamala Bay, about 5 miles from the Honolulu airport.

The captain told investigators that both engines started and other indicators appeared normal before takeoff. As the plane climbed, the cockpit voice recorder captured a thudding sound, then vibrations. Both pilots noted that the right engine had lost power, but it was thrust to the undamaged left engine that was reduced steadily to near idle power, the NTSB said.

The 58-year-old captain had more than 15,000 hours of flying time, and the co-pilot had more than 5,000 hours.

The Pratt & Whitney engines were made in 1968 and 1971 and had last been in the maintenance shop in 2019, the NTSB said. The plane had undergone all required inspections and maintenance checks and underwent a routine daily check that turned up no problems the day before the accident, according to the NTSB.

The plane was recovered about 400 feet below the ocean surface. Sheared-off fan blades were found on the engine that failed. The Federal Aviation Administration suspended Rhoades Aviation flights after the accident.