As investigators scramble to determine what caused a Boeing 737-800 to crash early Wednesday, the plane's maker is grappling with another catastrophe as it continues to reel from its 737 Max crisis.
The Ukraine-bound 737-800 crashed shortly after takeoff from Tehran's main international airport, killing all 176 on board. Early reports from Iranian state media attributed the crash to engine failure. Ukraine's embassy in Iran at first concurred, issuing a statement ruling out terrorism but then removed it without explanation.
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A later statement from the embassy said a panel has begun an investigation and "any statements about the causes of the accident before the decision of the commission are not official."
The disaster comes as Boeing struggles to rehabilitate its image after two fatal crashes within five months led to the global grounding of its 737 Max in 2019. That crisis has cost Boeing more than $9 billion and led to the firing of chief executive Dennis Muilenburg just weeks ago. The Chicago-based company is facing scores of lawsuits from victims' families, shareholders and airlines such as American and Southwest. In December, Boeing announced it would indefinitely stop production on the Max in January - which it had continued to produce at the cost of $1.5 billion a month - a stoppage that could ripple throughout the economy and jeopardize tens of thousands of manufacturing jobs.
The 737-800 is one of Boeing's most popular planes, with thousands in operation worldwide. It's part of a class of aircraft known as "next generation," or NG, which has been in service since the mid-1990s, and does not use the MCAS flight control system whose flaws played a role in the 737 Max crashes in Indonesia and Ethiopia.
The Iran crash was the 10th fatal accident of a Boeing 737 NG plane in its commercial life, according to Todd Curtis, an aviation safety analyst for the website AirSafe.com. The plane has had about 0.06 fatal events per million flights, the lowest rate among modern aircraft that have flown for several years, Curtis said. A 737-800 was involved in a 2018 crash in Papua New Guinea that killed 47, a 2016 flight from Dubai that killed 62, and a 2010 Ethiopian Ethiopian Airlines flight that killed 90.
The plane has faced regulatory scrutiny recently. In early October, the Federal Aviation Administration told airlines to inspect more than 1,900 Boeing jets after cracks were found in some of the aircraft's wings. Dozens of them were later grounded after cracks were found in a part of the plane that connects the wings to the fuselage.
"This is a tragic event and our heartfelt thoughts are with the crew, passengers, and their families," Boeing said in a tweet Wednesday. "We are in contact with our airline customer and stand by them in this difficult time. We are ready to assist in any way needed."
The Ukraine International Airlines jet that went down Wednesday was three years old and had been serviced on Monday, the Kyiv-based carrier said in a statement. After the crash, Ukraine and the flagship airlines of France, Germany and the Netherlands suspended flights in Iranian airspace.
The Iranian Students' News Agency, a state-run media organization, shared a video that it said showed the crash. In it, a ball of flame descends in the distance before erupting, lighting up the predawn sky. Another video tweeted by Iran's Tasnim News Agency showed parts of a plane scattered and on fire on the ground. Iranian officials and state-run media have attributed the crash to an engine fire.
"There is no similarity between the issue here and the Max," said John Cox, an airline safety consultant and former pilot, who described the plane as a "veteran workhorse."
The plane's CFM56 engines are jointly produced by General Electric and Safran, a French manufacturer. The CFM56 is among the best-selling jet engines in the world, with more than 30,000 of them delivered to date, according to the company's website. In a statement, the company said any speculation regarding the cause of the Iran crash is "premature."
Modern aircraft are designed to be able to fly safely for more than an hour in the event of engine failure with a single engine, but a significant failure could cause damage to other parts of an aircraft.
Rescue workers recovered the black box from the crash site, Iranian state media reported, but Ali Abedzadeh, head of Tehran's Civil Aviation Organization, said Tehran will not send it to the United States - as some countries do for assistance in data collection. He said Iran would lead in the investigation of the crash, which killed 82 Iranians, 63 Canadians and 11 Ukrainians, according to a tweet from Ukrainian Foreign Minister Vadym Prystaiko.
"Politics have no place in an accident investigation. We fly these airplanes all around the world, all across geographic borders," Cox said. "The investigation needs to be excluded from the tensions of any governments. I am hopeful the Iranians will follow international protocol and allow any parties that can add value to the investigation."
He added grounding the plane would be "ill-advised" until much more information is available.
Boeing is the single biggest component of the Dow Jones industrial average. Commerce Secretary Wilbur Ross told CNBC in August that problems with the 737 Max had been big enough to shave 0.4 percent off the entire U.S. gross domestic product for a period this year. Ross said he expected an uptick when the problems were fixed, but it's unclear what the effect might be, as Boeing is stopping the jet's production. Its shares fell 1.3 percent in premarket trading.
Curtis, who previously worked as a safety engineer at Boeing, said the company typically provides information to support crash investigations outside the United States.
"Even if Boeing can't be in the investigation in Iran, it's likely they will be involved," he said.