Crash specialists baffled by Chinese jet's nosedive from 29000ft

Safety experts say speed of Boeing 737-800’s nosedive is extremely unusual: ‘[It is] hard to get the airplane to do this’

The plane crash in China that is believed to have killed all 132 people onboard on Monday has confused independent experts, who are at a loss to explain how the aircraft suddenly nosedived to the ground.

The Eastern Airlines’ Boeing 737-800 was flying from Kunming and was to land at Guangzhou’s International Airport in southern China.

The plane was cruising at around 29,000 feet, about 100 miles away from its destination, when it suddenly went into a steep dive and crashed, in the worst aviation disaster China has faced this decade.

Even as search operations continue, state broadcaster CCTV reported no survivors were found at the crash site.

Search teams are still looking for the flight’s black box that could help determine the exact reason for the crash, after analysis of its data.

But experts have already pointed to the unusual nature of the plane’s last available flight data. The plane was at a point in its journey when pilots usually prep for landing, but it instead plunged directly down from 29,000ft in less than two minutes.

John Cox, an aviation safety consultant and a former pilot, was quoted as saying by Bloomberg that it was “hard to get the airplane to do this”.

The Boeing 737-800 has an excellent safety record and has been deployed around the world since the 1990s, part of the Next Generation era. It preceded the 737 Max, which was grounded globally after two deadly crashes in Indonesia and Ethiopia.

Investigators are now keen to know what sets this crash apart from earlier accidents. The investigators will look at the weather the plane encountered, any distress calls made by the pilots during the flight or whether there was any technical failure, according to Bloomberg.

Profiles of crew members will also be carefully investigated.

Chinese president Xi Jinping has ordered a thorough investigation into the tragic disaster.

Jeff Guzzetti, the former accident investigation chief of the US’s Federal Aviation Administration, said the crash was “very odd”.

Experts said even though there have been crashes in which planes began suddenly dropping from altitude, major differences set this crash apart.

On 1 June 2009, Air France flight 447 fell more erratically and slower than the Boeing 737-800, according to France’s Bureau of Enquiry and Analysis for Civil Aviation Safety. All 228 people onboard the Airbus A330 had died.

Wang Ya’nan, the chief editor of Beijing-based Aerospace Knowledge, was quoted by the Global Times as saying that “it could be a very serious technical failure in which the plane inevitably enters a high-speed descent”.

He, however, also made it clear that the specific cause can only be determined after the black box is recovered and analysed.

In another example of a sudden airplane plunge, an Atlas Air Worldwide Holdings Inc cargo plane suddenly dove down in 2019, albeit from a much lower altitude.

A report by the US National Transportation Safety Board said the co-pilot was disoriented and pointed the plane’s nose towards the ground. The cargo plane also didn’t fall as rapidly as the China Eastern Airlines one did.

On 19 December 1997, a Silk Air 737-300 carrying 104 people had plunged in Indonesia, leading to the deaths of everyone onboard. The National Transportation Safety Committee said the plane fell at more than 38,000 feet per minute and a conclusion pointing to the pilot most likely crashing the plane deliberately was arrived at.

“The first thing accident investigators are going to have to determine is: was the aircraft all in one piece when it hit the ground, or did something fall off the aeroplane before it hit the ground?” Juan Browne, a Boeing 777 pilot and popular aviation vlogger, told the South China Morning Post newspaper.

“The video data to me suggests that the aircraft was in one piece,” he added.

But others are sceptical about jumping to conclusions too soon. Jean-Paul Troadec, a former director of the French Bureau of Enquiry and Analysis for Civil Aviation Safety, told AFP the data was “very unusual” and that it was “far too early” to draw conclusions.

“There’s really only one thing that can get the aircraft in that vertical of a descent and keep it there, and that is the elevator or the stabiliser trim,” Mr Browne explained.

He said that even in such a “devastating impact crater” it was possible for investigators to locate the elevator trim jackscrew – a threaded bolt that controls the position of the trim.

“If you can find where the nut on the jackscrew was located, you can get an idea of what the trim state of the aircraft was on impact.”