“The investigation will determine the cause,” one official said, noting that among the facts still in question are the precise distance the prop plane was from the carrier when it went down, and whether it had actually begun its approach to the ship.

Eight people, including some Japanese troops, were plucked from the water by helicopters belonging to the Reagan Carrier Strike Group less than 45 minutes after the crash.

The quick rescue response indicates plane, known as a COD for Carrier Onboard Delivery, was probably in sight of the carrier when it crashed.

An engine failure during landing, when the plane is going slow with its flaps down, would make it particularly difficult for a pilot to recover the aircraft, Navy officials say.

All the officials, who spoke on condition of anonymity because the investigation is still underway, cautioned against speculating about to the cause before all the facts are gathered, and witnesses interviewed.

Three sailors died in the crash: Lt. Steven Combs, who was identified by Navy officials as one of the two pilots, Aviation Boatswain’s Mate Airman Matthew Chialastri and Aviation Ordnanceman Airman Apprentice Bryan Grosso.

Combs sister, speaking to reporters on Sunday, said her brother was a hero who put the crippled plane down in the ocean “Sully” Sullenberger-style that allowed most of the passengers to survive.

“That aircraft is not meant to do a water landing and he was able to land it in a way that let people get back to their family,” Combs said through tears on Sunday, reported The Berkshire Eagle.

Combs said the grief felt by the family was “tremendous,” but said, “It does help a little bit, that even in his last moment he was looking out for others. I wouldn’t have expected anything less.”

“Steve flew the hell out of that plane,” said Navy spokesman Cmdr. Ronald Flanders. “Lt. Combs’ airmanship was nothing short of heroic, and was instrumental in savings the lives of the eight survivors.”