NTSB to probe United pilots, wing flaps on flight that plunged toward ocean

The National Transportation Safety Board has launched an investigation into why a United Airlines flight nosedived to within 775 feet of the Pacific Ocean — a probe that will center on the pilots and the aircraft’s wing flaps.

The NTSB opened a formal investigation into the terrifying Dec. 18 incident Tuesday, with sources telling the Air Current that it will focus on how and when the Boeing 777’s flaps were retracted, as well as the interaction between the two pilots.

Flaps are extended to help planes produce more lift during takeoffs and landings. They are retracted once the plane has achieved a stabilized climb, as well as a safe airspeed and altitude.

Timing of the flap retraction determines how much lift the wings generate during the critical early phase of flight.

United pilots told the outlet that a higher flap setting is typically used at Maui, where greater lift is necessary on its shorter 6,998-foot runway.

The pilot monitoring, not the one flying, is responsible for the retraction. It is unknown whether the pilot or co-pilot — who had a combined 25,000 hours of flight time — was at the controls at takeoff.

The pilots have been retrained, a United rep has told The Post without elaborating.

Passengers aboard Flight 1722 screamed in terror when the Boeing 777 plunged 1,400 feet in under a minute moments after taking off from Kahului Airport in Maui after reaching just 2,200 feet en route to San Francisco, the Air Current first reported.

The crew regained control when the plane was just 775 feet from the water — and everyone on board was subjected to forces nearly 2.7 times the force of gravity as it climbed sharply to 33,000 feet.

A pilot called air traffic control when the plane was at 1,400 feet, on its way to an initial altitude of 5,000 feet, according to LiceATC.net recordings cited by the outlet.

The controller instructed the pilot to climb to 16,000 feet and received the acknowledgment 17 seconds before the plane’s vertical speed decreased as it crossed 2,000 feet in stormy weather, TAC reported.

Passenger Stephan Schneck told TAC that it was clear the plane was making an extreme maneuver, but said “visibility was so bad, all we could see were clouds and fog, so it wasn’t evident how dangerously close to the ocean we were.”

He added: “In the moment, I couldn’t have told you if we dropped 200 feet or 2,000 feet.”

When the plane reached about 3,000 feet, the controller cleared the flight to a waypoint out in the Pacific. The pilot reportedly gave a standard acknowledgment: “United 1722 heavy, proceed direct EBBER.”

It was unclear if the controller in Hawaii had noticed the stomach-churning dive, according to TAC.

United and the Federal Aviation Administration have said the crew filed the appropriate internal safety reports after landing safely in San Francisco.

United said it did not notify the NTSB about the incident because it did not consider it to have risen to the agency’s reporting criteria, according to the outlet.

The NTSB said Tuesday that it expects a preliminary report about the incident in two to three weeks.

Meanwhile, FAA Acting Administrator Billy Nolen on Tuesday sent a memo to the agency’s management board with a blunt message called a “Safety Call to Action,” TAC said.

He mentioned the overall US aviation safety record, but reportedly wrote that “we cannot take this for granted. Recent events remind us that we must not become complacent. Now is the time to stare into the data and ask hard questions.”

He announced that he was launching a formal safety review team to “examine the U.S. aerospace system’s structure, culture, processes, systems, and integration of safety efforts,” according to the outlet.

In March, the FAA will reportedly hold a safety summit with aviation officials, unions and others to “examine which mitigations are working and why others appear to be not as effective as they once were.”

“We need to mine the data to see whether there are other incidents that resemble ones we have seen in recent weeks. And we need to see if there are indicators of emerging trends so we can focus on resources to address now,” Nolan wrote, according to TAC.

It is unclear if United Airlines has offered any compensation to the passengers on the harrowing flight, with a spokesperson telling The Post Wednesday that the company had nothing to share about customer compensation.