United pilots miscommunicated. The NTSB says their error caused a plane to plunge more than 1,000 feet

A United Airlines flight plunged more than 1,000 feet toward the ocean shortly after takeoff from Hawaii because of miscommunication between pilots, the National Transportation Safety Board found in a report released Thursday. 

The plane from Kahului to San Francisco took off during heavy rain on Dec. 18 with 271 passengers and 10 crew members on board. It was a normal takeoff, but noting some airspeed fluctuations and turbulence, the captain asked the co-pilot to reset the wing flaps to five. The co-pilot heard "15" instead, according to the NTSB.

The Boeing 777, which had climbed to 2,100 feet, quickly plummeted down to about 748 feet above the ocean. The pilots remember hearing warnings from the ground proximity warning system. 

"Pull up, pull up" the first officer recalled saying. 

The crew was able to recover and safely continue to San Francisco without further incident, according to the NTSB report.

The official NTSB finding of the plunge says that the flight crew failed to manage the airplane's vertical flightpath, airspeed and pitch attitude after the miscommunication. The NTSB did not hear about the incident until about two months after it happened. By that point, the cockpit voice and flight data recorder information was no longer available. Investigators used flight crew statements and other records instead during the investigation. 

The plane was not damaged and no one was hurt, but passengers screamed when the plane plunged. Rod Williams was on the flight with his wife and two young children. 

"We took off a normal rate of climb and then all of a sudden the nose pitched up pretty, pretty dramatically for maybe 3 to 5 seconds," he previously told CBS News. "And at that point, there were a number of screams that were let out because it was, you know, an unusual climb at that point. But it was very brief and it was followed by a very dramatic descent. "

Both pilots received additional training after the incident. They continue to fly for the company, a United spokesperson said. 

In the aftermath of the incident, the airline said it closely coordinated with the Federal Aviation Administration and the Air Line Pilots Association on the investigation. 

"There's nothing more important than the safety of our crew and customers, which is why we're drawing on the lessons learned from this flight to inform the training of all United pilots," the United spokesperson said. "Our pilots voluntarily reported this event and United fully cooperated with the independent investigation so that insights could be used to enhance the safety of the entire industry."

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Aliza Chasan

Aliza Chasan is a digital producer at 60 Minutes and CBS News.

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