Passenger describes 'screaming' and 'praying' aboard United flight as it plunged within 800 feet of the Pacific Ocean

• A United Airlines flight plummeted to 800 feet above the Pacific Ocean in December.
• A passenger on the flight, Rod Williams, told CNN it felt like a "roller coaster."

A passenger on board a United Airlines flight that plunged within 800 feet of the Pacific Ocean told CNN that people were "screaming" and "praying" on board.

Rod Williams said he and his family were flying home from a family vacation in Maui, Hawaii, on December 18, when the incident happened.

Williams told CNN in an interview on Monday that shortly after take-off, the Boeing 777-200 started climbing at "a concerning rate" for a few seconds.

"It felt like you were climbing to the top of a roller coaster," Williams told CNN. "It was at that point, there were a number of screams on the plane. Everybody knew that something was out of the ordinary, or at least that this was not normal."

The plane climbed 2,200 feet before it suddenly took a plunge, falling around 1,425 feet in 18 seconds, according to data from FlightRadar24.

"When the plane started to nosedive, multiple screams are being let out at that point," Williams told CNN.

"You're trying your best to maintain your composure – there are obviously kids on the flight – nobody really knows what's going on, but at the same time, you're concerned. You don't know if this is an issue, but it was certainly out of the ordinary."

Williams said that during the descent, he looked at his wife who was sitting on the other side of their two children.

"It's tense, you don't really have a chance to speak or to conjure up words, you're just kind of gripping the seat and praying under your breath," he said. "I asked her later and sure enough … we were praying for a miracle because we felt like this could be it."

The plane came within 775 feet of hitting the ocean before it abruptly leveled out.

The crew reported the incident after landing safely in San Francisco, a spokesperson for United Airlines told Insider. The pilots, who had a combined 25,000 hours of flight time, received additional training, they added.

It is unclear what exactly caused the flight to nosedive, and the Federal Aviation Authority told Insider that reports about safety events and issues are kept confidential.

Williams said he did not know just how close it came to crashing until this week.

"Now that I know, statistically what had happened, and that we were about 5 to 5.2 seconds from hitting the water, you know, I'm definitely counting my blessings," he said.