Lion Air plane crash

Ethiopia Airlines Crash: Boeing urged to review plane controls
Ethiopia's transport minister says pilots were unable to control an aircraft that crashed last month.

Pilots certain of the crash causes

Today Programme

BBC Radio 4

One of the black boxes recovered from the Ethiopian Airlines crash site
AFP
One of the black boxes recovered from the Ethiopian Airlines crash site

Although both the voice recorders and the flight data recorders on the two fatal Boeing 737 Max plane crashes have been retrieved, it will take several months before the full investigations into the crashes is complete.

However, Captain Tilmann Gabriel, director of aviation at London City University and executive chairman of the International Pilot Training Association, says that pilots in the industry feel the cause is already clear, looking at information garnered from initial investigations - it has to do with the Manoeuvring Characteristics Augmentation System (Mcas) control system software.

"The voice recorder and the data recorder, as with the Lions crash, it will take several months to get clear, but it is very clear from the initial investigation that both the crashes are linked to the same problem, and it is an issue that the FAA has relied very much on Boeing to do this investigation," Captain Gabriel told Today.

"Now all the other aviation agencies in Europe and Asia are doing their own investigations, which is not what Boeing wanted."

Note: For an explanation of how Mcas works, see earlier posts today.

'Mcas wasn't explained to pilots'

Today Programme

BBC Radio 4

Boeing 737 Max jets taking off
Getty Images

An aviation industry veteran has told BBC Radio 4's Today programme that the controversial Manoeuvring Characteristics Augmentation System (Mcas) control system software on the Boeing 737 Max planes was not properly explained to pilots.

"Boeing, with the blessing of the FAA a couple of years ago, was not talking about it, and the system in the cockpit is absolutely not explained to the pilots," Captain Tilmann Gabriel, director of aviation at London City University, and executive chairman of the International Pilot Training Association,told the BBC.

"The only mention of the Mcas system in the pilots manual is in the abbreviations [section]."

He said that pilots in the industry are well trained to fly the existing Boeing 737 plane models, but in the cases of the two 737 Max crashes, the pilots "didn't know what they had to do" because they didn't understand what Mcas was or how it worked.

Note: For an explanation of how Mcas works, see earlier posts today.

FAA under scrutiny over Boeing inspections

Families of the Ethiopia Airlines plane crash victims attend a mass funeral
Reuters
Families of the Ethiopia Airlines plane crash victims attend a mass funeral

The other part of the Boeing 737 Max story is that the US Federal Aviation Authority (FAA) is now under scrutiny for the way in which new aircraft are certified as being safe.

On 17 March, current and former safety engineers who handle plane safety evaluations for the FAA told the Seattle Times on condition of anonymity that the FAA forced safety engineers to delegate safety assessments of new aircraft to Boeing itself, in order to speed up the approval process.

The US government is now scrutinising the FAA - it appeared before Congress on Wednesday to explain its actions, and evidence was also heard from the Department of Transportation.

What changes is Boeing making?

Boeing logo
Reuters

On Wednesday, Boeing held a press conference announcing that it will be issuing several updates to the control system software on its 737 Max planes, which are currently grounded worldwide.

In addition to investigations into the Lion Air and Ethiopian Airlines crashes, the aviation authorities of several countries are now conducting their own independent investigations into the airworthiness of the 737 Max.

Boeing said it will install a warning system to alert pilots if Mcas is receiving conflicting data from its sensors, and it has also redesigned the software to disable the system completely if it receives conflicting data.

Previously, the warning system was an optional safety feature, and neither the Lion Air or the Ethiopian Airlines planes were carrying it.

However, Boeing told reporters the upgrades were not an admission that the system had caused the crashes.

Boeing 737 Max: A recap

Boeing 737 Max
Boeing

Over the last five months, there have been two fatal crashes of Boeing 737 Max planes.

Due to safety concerns pending the outcomes of investigations, Boeing's entire fleet of 737 Max planes has been grounded worldwide, and it is not clear when the planes will be allowed to fly again.

Initial investigations strongly suggest a problem with the plane's software control systems.

Compared to earlier versions of the 737, the Max features larger engines, mounted higher on the wing. These create a certain amount of extra lift. As a result, when the plane is flying with the nose up at a steep angle, the aircraft’s controls can feel lighter than usual.

The Manoeuvring Characteristics Augmentation System (Mcas) was introduced by Boeing to make the handling of the plane more predictable, and more familiar to pilots – so that it felt much more like earlier versions of the 737 to fly.

By pitching the nose downwards, it also reduces the risk of a stall – where the nose points upwards too much and the wings do not produce as much lift.

An investigation of the Lion Air flight last year suggested the system malfunctioned, meaning that the plane's computer forced the nose of the plane down more than 20 times, before it crashed into the sea, killing all 189 passengers and crew.

The US Federal Aviation Administration (FAA) says there are similarities between that crash and the Ethiopian accident on 10 March.