A United Airlines flight that took off from the Hawaiian island of Maui late last year made a steep dive shortly after takeoff and came within 800 feet of the Pacific Ocean before regaining altitude.
The harrowing incident was first reported on Sunday by The Air Current, an aviation news site.
On Dec. 18, United Airlines flight 1722 left Kahului Airport bound for San Francisco and reached 2,200 feet before experiencing a precipitous descent that brought the aircraft just 775 feet above water, the website reported.
The plane was able to regain altitude quickly and ultimately completed its journey to California. The incident lasted about 45 seconds.
"There were a number of screams on the plane," passenger Rod Williams II told CBS News. "Everybody knew that something was out of the ordinary, or at least that this was not normal."
United Airlines spokesman Josh Freed said in an email to NPR that the pilots filed a safety report after landing in San Francisco.
The two pilots, who together have roughly 25,000 hours of flying experience, are now receiving additional training following an investigation involving the airline, the Federal Aviation Administration and the Air Line Pilots Association, a pilots' union. Pilots typically need a minimum of 1,500 flight hours to be certified as first officers at commercial airlines.
United said there were no injuries related to the incident. "Safety remains our highest priority," Freed said.
It's unclear what caused the drop. United told The Air Current that the incident wasn't related to any problem with the plane. The publication reported that there were clouds and heavy rain in Maui that day.
In a statement, the FAA confirmed that the United Airlines flight crew voluntarily reported the incident to the agency. The FAA said it reviewed the incident and took "appropriate action" but gave no additional details.
The National Transportation Safety Board, which investigates civil aviation accidents, said it was gathering information about the incident but had not initiated an investigation.