Debris from a United Airlines flight that made an emergency landing in Denver. (Broomfield Police Department)

 A United Airlines passenger jet en route to Hawaii and carrying hundreds of passengers experienced a dramatic engine failure Saturday over the Denver area and dropped a large amount of debris on neighborhoods before safely making an emergency landing.

The massive Boeing 777-200 plane — one of the largest aircraft in United’s fleet — landed safely at Denver International Airport and no injuries were reported either aboard the aircraft or on the ground, authorities said.

Police said it was miraculous that no one on the ground was hurt given the amount of debris that fell from the sky and the populated area that it descended upon.

The National Transportation Safety Board said it has opened an investigation into the incident. Local authorities are looking into the situation, too.

Photos posted by the Broomfield Police Department showed large, circular pieces of the engine’s cowling leaning against a house in the suburb about 25 miles north of Denver. People called 911 to report a loud explosion. Some thought the aircraft was falling out of the sky after its right engine broke apart and caught fire.

Other photos showed smoke trailing from the right engine as the pilot declared “mayday” and requested permission to return to the airport and make an emergency landing.

The plane banked low and loud over Denver as it returned to the airport.

One of the pilots flying the plane called air traffic controllers and declared “mayday, mayday,” saying they had an engine failure.

“Need to turn immediately,” the pilot said.

United said in a statement that there were 231 passengers and 10 crew on board Flight 328. All passengers were to be rebooked on a new flight to Hawaii, the airline said.

“We are in contact with the FAA, NTSB and local law enforcement,” the airline said in a written statement.

Some homes were damaged by the debris. Other pieces of the engine fell on a popular soccer field in Commons Park. Some captured video of pieces of the engine fluttering from the sky. Residents reported insulation raining down on their neighborhoods.

“People started calling us saying ‘there’s basically a plane falling from the sky,'” said a Broomfield police spokeswoman.”The fact that we are not getting any reports of any injuries is absolutely shocking.”

Broomfield police reiterated the sentiment on Twitter Saturday night.

“Given the number of people who are at Commons Park on a weekend day we are beyond grateful that no one was injured,” the department said on Twitter.

Police asked people to leave the debris in place so that the NTSB can investigate. A reverse-911 call was sent out to about 1,400 Broomfield resident altering them to the situation.

Passengers recounted a terrifying ordeal that began to unfold shortly after the plane full of vacationers took off.

The captain was giving an announcement over the intercom when a large explosion rocked the cabin, accompanied by a bright flash, passengers told The Associated Press.

“The plane started shaking violently, and we lost altitude and we started going down,” said David Delucia, who was sitting directly across the aisle from the side with the failed engine. “When it initially happened, I thought we were done. I thought we were going down.”

Delucia and his wife took their wallets containing their driver’s licenses and put them in their pockets so that “in case we did go down, we could be ID’d,” said Delucia, who was still shaken up as he waited to board another flight for Honolulu.

On the ground, witnesses also heard the explosion and were scared for those on board.

Tyler Thal, who lives in the area, told the AP that he was out for a walk with his family when he noticed a large commercial plane flying unusually low and took out his phone to film it.

“While I was looking at it, I saw an explosion and then the cloud of smoke and some debris falling from it. It was just like a speck in the sky and as I’m watching that, I’m telling my family what I just saw and then we heard the explosion,” he said in a phone interview. “The plane just kind of continued on and we didn’t see it after that.”

Thal was relieved to learn later that the plane had made a safe landing.

Kirby Klements was inside with his wife when they heard a huge booming sound, he told the AP. A few seconds later, the couple saw a massive piece of debris hurtle past their window and into the bed of Klements’ truck, crushing the cab and pushing the vehicle into the dirt.

He estimated the circular engine cowling at 15 feet in diameter. Fine pieces of the fiberglass insulation used in the airplane engine fell from the sky “like ash” for about 10 minutes, he said, and several large chunks of insulation landed in his backyard.

“If it had been 10 feet different, it would have landed right on top of the house,” he said in a phone interview with the AP. “And if anyone had been in the truck, they would have been dead.”

Video taken by passengers on the plane, en route from Denver to Honolulu, showed flames shooting from one of its massive engines.

“United flight 328 departed from DEN this afternoon and returned shortly after with reported mechanical issues,” Denver International Airport said in a tweet. “The aircraft has landed safely and no injuries have been reported. Big thanks to the pilot and crew for safely landing the aircraft.”

FlightAware, a flight tracking website, shows the plane departed Denver International Airport heading west at about 12:50 p.m. It reached an altitude of about 13,500 feet near the Rocky Mountain Metropolitan Airport in Broomfield when it began a quick left turn and descent beck toward DIA.

The plane reached a maximum speed of 382 miles per hour.

The entire flight lasted about 40 minutes, only about 25 of which the plane was in the air.

United flight 328 is a daily flight from Denver to Honolulu’s Daniel K. Inouye International Airport. It typically lasts about seven hours. United uses a Boeing 777 as well as a Boeing 757 on the route.

The twin-engine Boeing 777 is one of the world’s most advanced, safest airplanes. It is designed to fly on one engine in an emergency situation.

Aviation safety experts told the AP that the plane appeared to have suffered an uncontained and catastrophic engine failure. Such an event is extremely rare and happens when huge spinning discs inside the engine suffer some sort of failure and breach the armored casing around the engine that is designed to contain the damage, said John Cox, an aviation safety expert and retired airline pilot who runs an aviation safety consulting firm called Safety Operating Systems.

“That unbalanced disk has a lot of force in it and it’s spinning at several thousand rotations per minute … and when you have that much centrifugal force, it has to go somewhere,” he said in a phone interview.

Pilots practice how to deal with such an event frequently and would have immediately shut off anything flammable in the engine, including fuel and hydraulic fluid using a single switch, Cox said.

Former National Transportation Safety Board Chairman Jim Hall called the incident just another example of “cracks in our culture in aviation safety (that) need to be addressed.

Hall, who was on the board from 1994-2001, has criticized the FAA over the past decade as “drifting toward letting the manufacturers provide the aviation oversight that the public was paying for.” That goes especially for Boeing, he told the AP.

Despite the scary appearance of a flaming engine, most such incidents don’t result in loss of life, Cox said. 

The last fatality on a U.S. airline flight involved such an engine failure on a Southwest Airlines flight from New York to Dallas in April 2018. A passenger was killed when the engine disintegrated more than 30,000 feet above Pennsylvania and debris struck the plane, breaking the window next to her seat. She was forced halfway out the window before other passengers pulled her back inside.

In that case, the breakdown was blamed on a broken fan blade in an engine of the Boeing 737. The Federal Aviation Administration ordered airlines to step up inspections of fan blades on certain engines made by CFM International, a joint venture of General Electric and France’s Safran S.A.

In 2010, a Qantas Airbus A380 suffered a frightening uncontained engine failure shortly after takeoff from Singapore. Shrapnel from the engine damaged critical systems on the plane, but pilots were able to land safely. The incident was blamed on faulty manufacturing of a pipe in the Rolls Royce engine.

“The flames scare the hell out of everybody but they are the least of the problem because you’re going to get them put out and you’re going to shut off everything that can burn,” Cox said.

The Associated Press contributed to this report.

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Jesse Paul is a Denver-based political reporter and editor at The Colorado Sun, covering the state legislature, Congress and local politics. He is the author of The Unaffiliated newsletter and also occasionally fills in on breaking news coverage.

A Colorado College graduate, Jesse worked at The Denver Post from June 2014 until July 2018, when he joined The Sun. He was also an intern at The Gazette in Colorado Springs and The News Journal in Wilmington, Delaware, his hometown.

Jesse has won awards for long form feature writing, public service reporting, sustained coverage and deadline news reporting.

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