ADDIS ABABA, April 4 (Reuters) - Ethiopian
Airlines pilots followed proper procedures when their Boeing MAX 8 airplane
repeatedly nosedived before a March 10 crash that killed 157 people, Ethiopia's
minister of transport said on Thursday as she delivered the first official
report on the disaster.
"The crew performed all the procedures repeatedly provided by the
manufacturer but was not able to control the aircraft," Dagmawit Moges told a
news conference in the capital, Addis Ababa.
In line with international rules on air accidents, the preliminary
report did not attribute blame. Nor did it give a detailed analysis of the
flight, which is expected to take several months before a final report due
within a year.
But in a clear indication of where Ethiopian investigators are
focusing most of their attention, the report cleared the pilots of using
incorrect procedures and issued two recommendations directed at planemaker
Boeing and regulators.
It suggested that Boeing review the aircraft control system and
aviation authorities confirm the problem had been solved before allowing that
model of plane back into the air. It was grounded globally following the crash,
which was the second deadly accident in six months involving the new model after
a Lion Air crash in Indonesia in October that killed 189 people.
"Since repetitive uncommanded aircraft nose down conditions are
noticed ... it is recommend that the aircraft control system shall be reviewed
by the manufacturer," Moges said.
Ethiopian Airlines said its crew had followed all the correct
guidance to handle a difficult emergency.
However, the report could spark a debate with Boeing about how crew
responded to problems triggered by faulty data from an airflow sensor,
particularly over whether they steadied the plane before turning key software
off.
Boeing said it would study the report.
Families of the victims, regulators and travellers around the world
are waiting for clues to the accident after the new Boeing jet crashed six
minutes after take-off.
The preliminary report into the Lion Air disaster said the pilots
lost control after grappling with the plane's Manoeuvring Characteristics
Augmentation System (MCAS) software, a new automated anti-stall feature that
repeatedly lowered the nose of the aircraft based on faulty data from a
sensor.
Boeing said on Wednesday it had successfully tested an update of the
MCAS software designed to reduce its authority and make it easer for pilots to
handle.
(Reporting by Jason Neely, Editing by Tim Hepher and Mark Potter)
Ethiopia to issue first Boeing investigation
report
By Eric M. Johnson, Tim Hepher and Jason Neely
ADDIS ABABA/SEATTLE/PARIS, April 3 (Reuters) -
Investigators will release a keenly awaited report on the deadly
crash of an Ethiopian Airlines jet on Thursday, Ethiopia's transport ministry
said, giving the first official clues to the second crash of a new Boeing 737
MAX in five months.
Some 35 nationalities were among the 157 passengers and crew who died
when the nearly full plane crashed six minutes after take-off from the capital
Addis Ababa in clear conditions.
The March 10 disaster prompted the worldwide grounding of Boeing's
best-selling plane and scrutiny of its certification process.
"The 10:30 a.m. (0730 GMT) press conference is to present the
preliminary report," Ethiopian transport ministry spokesman Musie Yehyies
said.
The report may shed light on how a piece of cockpit software came
back to life after pilots initially switched it off as they tried to save the
doomed jet, people familiar with the matter said, placing both technology and
crew in the spotlight.
The Ethiopian-led investigation has begun piecing together details of
flight 302, starting with faulty sensor data on take-off from Addis Ababa,
questions over the Boeing 737 MAX's high speed and a nosedive coinciding with
the software re-activation.
The aircraft's high speed and initial climb suggests the engines were
running at a higher than usual thrust, experts say.
The so-called MCAS anti-stall software is at the centre of accident
probes in both the Ethiopian crash and October's Lion Air accident in Indonesia
that have together killed 346 people.
MCAS was designed to help prevent an aerodynamic stall by issuing
commands to push the plane's nose lower. However, in both cases it is suspected
of firing up in response to faulty airflow data from a single sensor designed to
measure the 'angle of attack,' a parameter needed to avoid stalling or losing
lift.
SENSOR PROBLEMS
Echoing the fate of the Lion Air jet, initial evidence suggests the
Ethiopian Airlines jet experienced sensor problems shortly after take-off,
causing the MCAS software to begin lowering the nose to grab air under the
wings.
Unlike the Lion Air crew, who were flying at a time when pilots had
been told little about the MCAS software, the Ethiopian crew used switches to
turn the automatic system off but it later re-engaged, people familiar with the
matter said.
Although aircraft experts say MCAS cannot turn back on by itself, the
report is expected to shed light on whether and why the crew chose to restore
electrical power to the system at the risk of setting off more automated
nose-down movements.
Aerospace analyst Bjorn Fehrm said in a blog post for Leeham News
that pilots may have deliberately re-activated the system in order to make it
easier to trim or control the aircraft only to be overwhelmed by rapid
counter-moves from MCAS.
Investigators will also look at whether the crew carried out all
necessary procedures, including a recommendation to stabilise the plane using
the trim system before turning the crucial software off.
The pilots manoeuvred the plane upwards at least two times before
hitting the stabilizer cut-out switches to disable the system, one person
familiar with the matter said.
However, initial flight data indicates the aircraft was flying
nose-heavy and not in a "neutral" attitude when pilots hit the cut-out switches,
the person added, making the situation harder to manage.
Cockpit procedures call for pilots to leave the MCAS system off for
the rest of the flight once it has been disengaged.
GLOBAL GROUNDING
Safety experts stress the investigation is far from complete and most
aviation disasters are caused by a unique combination of human and technical
factors.
In a statement, Boeing said: "We urge caution against speculating and
drawing conclusions on the findings prior to the release of the flight data and
the preliminary report."
The 737 MAX is Boeing's top-selling jet with almost 5,000 on order.
Ethiopian Airlines is also in the midst of an expansion drive, while other 737
MAX customers and victims' families want answers, and potentially compensation.
Boeing shares were down 1.5 percent at 1800 GMT. They have lost more
than 8.5 percent since the Ethiopian crash.
Getting the planes flying again depends partly on the role that
Boeing design features are found to have played in the crash, though
investigators are also paying attention to airline operations, crew actions and
regulatory measures.
Boeing is upgrading the MCAS software and training while stressing
that existing cockpit procedures enable safe flight. It however faces mounting
lawsuits alleging poor system design.
The Wall Street Journal reported earlier that the pilots had
initially followed Boeing's emergency procedures but later deviated from them as
they tried to regain control of the plane. (Full
Story)
(Reporting by Eric M. Johnson, Tim Hepher, Jamie Freed, Jason Neely,
David Shepardson; Editing by Georgina Prodhan, Mark Potter and Kirsten
Donovan)
|
Boeing software re-activated before Ethiopian crash -sources
By Eric M. Johnson and Tim Hepher
SEATTLE/PARIS, April 3 (Reuters) - Boeing
anti-stall software on a doomed Ethiopian Airlines jet re-engaged and pushed the
jet downwards after the pilots initially turned it off due to suspect data from
an airflow sensor, two people familiar with the matter said.
It was not immediately clear whether the crew chose to re-deploy the
MCAS system, which was designed to push the nose of the 737 MAX down to prevent
one kind of emergency but which is suspected of exacerbating a scenario linked
to two crashes.
But investigators are studying the possibility that the software
kicked in again without human intervention, one person with knowledge of the
matter said, while a second said the software had engaged as many as four
times.
A third person familiar with the initial findings of an investigation
into the cause of the crash, confirmed the software had fired up again, but said
there was only one significant episode after the crew turned it
off.
A Boeing spokeswoman declined to comment, while Ethiopian
investigators were not available for comment.
Boeing's anti-stall software is at the center of investigations into
last month's Ethiopian Airlines crash and a Lion Air accident in Indonesia in
October that together killed a total of 346 people.
People familiar with the investigation have said the anti-stall
software - which automatically pushes the aircraft's nose down to guard against
a loss of lift - was activated by erroneous 'angle of attack' data from a single
sensor.
The investigation has now turned towards how MCAS was initially
disabled by pilots, in line with part of a cockpit checklist procedure, but then
appeared to start working again before the jet plunged to the ground, the people
said.
A directive issued after the Indonesian crash instructed pilots to
use cut-out switches to disengage the system in the event of problems and then
leave it switched off.
Doing so does not shut down the MCAS system completely but severs an
electrical link between the software and other aircraft systems, a person
familiar with the technology said.
Investigators are studying whether there are any conditions under
which MCAS could re-activate itself automatically, without the pilots reversing
the cut-out manoeuvre. Boeing is in the midst of upgrading the software and
adding extra training.
Investigators will also look at whether the crew carried out all
aspects of the procedure, including a recommendation to stabilize the plane
before turning the crucial software off.
The pilots maneuvered the plane back upwards at least two times
before hitting the stabilizer cut-out switches to disable the system, the second
person familiar with the matter said.
However, initial flight data indicates the aircraft was flying
nose-heavy and not in a "neutral" attitude when pilots hit the stabilizer cutout
switches to disable the MCAS system, the person added, making the situation
harder to manage.
After the pilots turned off MCAS, the airplane over the next few
minutes gained roughly 2,000 feet, but dived into the ground after the MCAS
system intervened again for reasons that remain unclear pending a preliminary
report expected within days.
Safety experts stress accidents are usually caused by a combination
of factors and the probe is at an early stage.
(Reporting by Eric M. Johnson in Seattle, Tim Hepher in Paris, Jamie
Freed in Singapore, Editing by Laurence Frost, Richard Lough and Alexander
Smith)
|
Ethiopian jet's data record deepens concern about 737 MAX
safety procedures Ethiopian Airlines accident scene Ethiopian Airlines Group CEO, Tewolde GebreMariam, visits the accident scene in Ethiopia hours after the March 10 crash. (Ethiopian Airlines Photo via Twitter) Readings from the recorders recovered from last month's crash of an Ethiopian Airlines Boeing 737 MAX jet reportedly suggest that the pilots tried using the recommended procedure for overriding a balky automated flight control system - but that the system was re-engaged and forced the plane into its fatal dive. The reports by The Wall Street Journal and Reuters, based on interviews with unnamed sources who have been briefed on the post-crash investigation's preliminary findings, raise deeper questions about the safety of the flight control system, known as the Maneuvering Characteristics Augmentation System, or MCAS. Boeing added the MCAS system to the 737 MAX as a safeguard against stalling, but investigations into the Ethiopian crash on March 10 - and last October's crash of a Lion Air 737 MAX in Indonesia - have focused on the possibility that spurious data from a single angle-of-attack sensor caused the system to force the planes into catastrophic nose dives. The Indonesia crash killed all 189 people on board, and the Ethiopian crash killed 157 people. In the wake of the crash in Ethiopia, all 737 MAX planes have been grounded worldwide. Boeing is working on a software update that it says should resolve the MCAS issue, but that fix is still thought to be weeks away. In the past, Boeing has stressed that pilots could remedy the scenario that led to the crashes by disconnecting the MCAS system and taking manual control of the jet's stabilizer trim mechanism. But the latest reports quote sources as saying the Ethiopian Airlines pilots tried that procedure but didn't fully execute it. Instead, the MCAS system was re-engaged, leading to the final, fatal plunge. The Journal's sources speculated that pilots re-engaged the automated system because they couldn't raise the nose using manual controls, while Reuters' sources held out the possibility that the MCAS system could have re-engaged itself. The Seattle Times quoted a former Boeing flight control engineers, Peter Lemme, as saying that the pilots might have been stymied by excessive aerodynamic loads on the stabilizer trim control system. I *assume* the mistrim situation created excessive load opposing the manual jackscrew authority from the trim wheel. From what is reported, they must have tried to restore electric trim to get the stab to come up, but then MCAS swept in again. Leeham News and Analysis also laid out a scenario by which excessive loads could have foiled efforts to stabilize the jet. The Times noted chatter on an online aviation forum about an alternate procedure, outlined in a 1982 pilot training manual, that might have averted the manual lockup by repeatedly letting go of the control column and turning the cockpit's stabilizer trim wheel manually. Boeing said it was premature to comment on the specifics of such reports. "We urge caution against speculating and drawing conclusions on the findings prior to the release of the flight data and the preliminary report," the company said. The 737 MAX crashes are the subject of investigations in Ethiopia and Indonesia, with participation by Boeing, the Federal Aviation Administration, the National Transportation Safety Board and other entities. The FAA's inspector general is conducting its own investigation into the process by which the 737 MAX was certified for flight, and the Justice Department has reportedly launched a grand jury investigation with participation by the FBI. Subpoenas have gone out to Lemme and other potential witnesses, The Seattle Times reported. |
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