Explained | Why did the China Eastern Airlines plane nose dive before crashing?

How does upset training and prevention help overcome environmental, physical and other factors during flight?

How does upset training and prevention help overcome environmental, physical and other factors during flight?

The story so far: On March 21, a China Eastern Airlines Corporation flight (MU5735) on a China domestic flight from Kunming to Guangzhou crashed into the ground west of Guangzhou in a mountainous area. The plane had 123 passengers and nine crew members on board. At a press briefing on March 23, the Civil Aviation Administration of China (CAAC) said one of the black boxes had been recovered but was “substantially damaged”. Suspicious debris (a large strip of metal) was also found 10 km from the crash site, indicating possible in-flight disintegration.

What happens to black boxes?

A CAAC briefing said that based on a preliminary assessment, the recovered black box device is the cockpit voice recorder and that “the recording equipment appeared to have survived the impact in relatively good condition”. It is being decoded in Beijing, according to a report.

A black box must be able to withstand many crash scenarios. A document from the German Federal Aircraft Accident Investigation Bureau states that “these devices are tested under extreme conditions such as impact with a concrete wall at 750 kilometers per hour; a static load of 2.25 tons for at least five minutes, a maximum temperature of 1,100 degrees Celsius (2,012 degrees Fahrenheit) for one hour, and water pressure at depths of up to 6,000 meters or more 19,500 feet.

An aviation expert says the data files must first be decoded, in the form of graphs, to get an idea of ​​what happened. There is even the use of “spectral analysis” in some cases allowing experts and investigators to spot even low alarms or the suspicion of an explosion.

The United States National Transportation Safety Board (NTSB) – invited by China – must participate in the investigation, because an American-made plane is involved.

An aviation expert says public and media pressure can be intense given that we live in a time when people want instant answers. He warns that getting an idea of ​​what could have happened could take days, preliminary reports could appear after a few months, while a detailed investigation could even take a year or more.

What are the additional flight details?

Flight MU5735 left Kunming around 1:10 p.m. local time and was due to land in Guangzhou shortly after 3:00 p.m. Commissioned in June 2015, the Boeing 737-800 aircraft powered by CFM56 engines had flown just over 18,000 hours. One report quoted a CAAC official as saying air traffic controllers had been in contact with the crew throughout the flight – the implication is that there was no emergency/distress call. Later, the crew did not respond to attempts to contact the controller, which could indicate that a catastrophic event had occurred.

The captain, who was employed in January 2018, had 6,709 hours of flight experience, while the first and second officers had 31,769 hours and 556 hours, respectively. The third pilot was an observer to accumulate flight experience. The CAAC added that the aircraft was airworthy and had been maintained in accordance with regulatory requirements. He also added that the family life of the crew was “relatively harmonious”.

Footage has also emerged – apparently captured on video security footage from a mining company, close to the crash site – which appears to suggest the plane was plunging towards land.

However, it was the data from the tracing sites that sparked the interest.

What does some of the data show?

A new 3D data visualization by a leading tracking website shows the plane had cruised at about 29,100 feet (nearly 9,000 meters; in China, flight levels are assigned in meters). It then plunged from 27,025 feet to 7,425 feet. There was a climb to 8,600 feet, then a second dive to 3,225 feet, at which point tracking stops – in total, a two and a half minute event. The dive rate was calculated at 157 meters per second.

Experts called this extremely excessive and unusual. An expert says it could be related to the plane’s tail. Or even sabotage.

In an e-mail in response to questions from The Hindu, David Learmount, Consulting Editor, Flightglobal/DVV Media International Ltd. (also former operations and safety editor, Flightglobal, and former flight instructor, Royal Air Force) said: “The capping may well have been an attempt at recovery by a pilot. But why was the attempt then reversed? Was it two or three riders fighting for different results,” he remarks.

He added: “Of course, until we have concrete data, sabotage or a major failure may be the cause.” Mr. Learmount also said that when looking at the issue of upset recovery – covered later in this FAQ – you need to look at what caused the upset.

In response to another request from The Hindu, Dr. Hassan Shahidi, President and CEO, Flight Safety Foundation, USA, said: “This accident is very puzzling. The 737-800 series has an excellent safety record. There are more than 4,200 in operation worldwide and more than 1,100 in China. Investigators will examine all aspects of this accident, including mechanical and structural. They will look at the maintenance history of this plane as well as the training of the pilots.

“This is certainly an unusual accident. At this time, it is difficult to imagine what could have caused this plane to dive at high altitude. We will not know the cause until the investigators have The data from the recorders will be crucial in understanding what happened as the plane began its rapid descent.

What about the issue of thwarted recovery?

A senior commander who flies the Boeing 777 said The Hindu that the issue of upset recovery could also come into the equation.

A senior commander who flies the Airbus family of aircraft said The Hindu“Yes, it does matter whether it was some kind of upset or disorientation that caused this accident. Upset recovery training would help a pilot deal with any unusual aircraft attitude due to environmental factors, physical factors such as disorientation or instrumental factors such as unreliable airspeed (as seen in the Air France AF447 crash, June 2009), etc. would not be very relevant for cases involving a serious structural or mechanical failure. More data will be needed to understand what caused the crash in China,” he said.

Data on commercial aircraft accidents and fatalities show that loss of control in flight is a leading cause. It is in recognition of this that the aviation industry and its regulators – including India – have begun to focus on disruption prevention and recovery training, or UPRT.

UPRT is a mix of theory and flight training, teaching the flight crew to avoid and recover from situations in which an aircraft unintentionally exceeds normal flight parameters.

In aviation, flight crews face a variety of weather systems and issues, with thunderstorms being considered one of the most dangerous. Therefore, if the crew is caught in a thunderstorm, the UPRT will teach them to familiarize themselves with where the greatest threat could arise from. And also the best recovery techniques.

UPRT, says Boeing’s Commander-in-Chief, is most certainly necessary for professional pilots.

A paper on UPRT states that in an upset there is an ecosystem of causes, which includes “environment, system systems and malfunctions, aerodynamic problems, pilot induced/human factor and/or their combinations of the above”. UPRT training covers all of this. And, in crew training, the emphasis is on prevention. The main purpose of the training is to equip the flight crew to “resolve an upset condition, both technically and emotionally.”

Preparing pilots not only for pilot skills training, but also “integrating circumstances and precursors” that could cause upset, constitute the technical aspects of training. Unexpected mental shock, G-forces, noises and even changes in environmental conditions can affect the flight crew, impacting their ability to make decisions and act.

Pilots around the world are equipped with varying levels of skill and technical knowledge. The quality and type of their flight training also differ. Suffice it to repeat that UPRT must provide a critical level of training when dealing with the threats posed by upset conditions.