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BA Boeing Co

192.91
0.96 (0.50%)
29 Mar 2024 - Closed
Delayed by 15 minutes
Share Name Share Symbol Market Type
Boeing Co NYSE:BA NYSE Common Stock
  Price Change % Change Share Price High Price Low Price Open Price Shares Traded Last Trade
  0.96 0.50% 192.91 193.38 191.20 192.00 4,465,114 00:00:00

Lion Air Crash Probe Eyes Sensor Hazards Stretching Back Years -- Update

18/11/2018 7:50pm

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By Andy Pasztor and Robert Wall 

Aviators around the globe have long recognized potential hazards of malfunctioning flight-control sensors similar to the one implicated in last month's Lion Air jet crash. Now, investigators are examining how plane maker Boeing Co. heeded those earlier warnings.

The latest investigation has expanded to delve into whether Boeing -- as well as regulators specifically responsible for certifying the sensor system -- fully incorporated those earlier safety lessons into the final design of the Boeing 737 MAX 8, the model that crashed in Indonesia, according to industry and government officials.

The Federal Aviation Administration, which oversaw the design and testing of the suspect sensor and related hardware, has said it is reviewing risk analyses and pilot-training requirements originally developed by Boeing. These actions are part of the crash investigation led by Indonesian authorities, according to the agency.

In a statement Sunday, Boeing said it "continually learns from its fleet experience, which includes closely following aircraft incidents and airworthiness directives that are issued, and then strives to incorporate lessons learned into its designs and recommended procedures." The company also reiterated it continues to provide technical assistance to investigators examining the Lion Air crash.

Called angle-of-attack indicators, the system sends data to flight-control computers about how high or low a plane's nose or wings are compared to level flight. But if erroneous information is transmitted in certain situations while pilots are flying manually, the plane's computers will automatically and repeatedly push the nose down. Investigators have said publicly this is what they believe occurred on Lion Air Flight 610, because some apparent problem with the sensor system incorrectly indicated the plane was on an excessively steep climb at a relatively slow speed.

On MAX 8 models, under certain conditions, pilots may be unable to pull the plane out of a dive unless they react quickly and proceed to the most relevant portion of their emergency checklist. One fundamental question is how the FAA gave the green light for a system in which one malfunctioning sensor -- called a "single point failure" in engineering lingo -- can lead to a catastrophic dive.

Investigators haven't determined exactly what role erroneous angle-of-attack data played in the Lion Air tragedy, and other potential malfunctions or factors may have contributed. In addition, since the crash, Boeing has said its flight manuals and training materials adequately addressed the risks, privately telling pilots and airlines that any pilot who follows required procedures can avoid a crash, according to government and industry officials familiar with the discussions.

In addition to sensor hardware, investigators also are looking into operation of separate software used to digitally process signals from sensors.

As far back as 2013, however, regulators on both sides of the Atlantic issued safety directives mandating emergency pilot responses to ensure that failures of the same type of sensors on long-range Airbus SE A330 and 340 models didn't result in an uncontrolled dive. Concluding that in some cases an aircraft's nose couldn't be raised even with maximum pilot manual commands, regulators ordered that suspect parts be replaced.

The following year, the European Aviation Safety Agency issued an emergency order revising certain cockpit procedures to deal with blocked angle-of-attack sensors on thousands of Airbus wide-body and narrow-body jets. And just last month, U.S. regulators increased the number of Airbus A319 and A320 models included in a different safety directive also focused on the dangers of blocked sensors.

Those previous actions primarily covered angle-of-attack sensors that were blocked or rendered temporarily inoperative by icing. The Lion Air probe is assessing other potential causes for problems with the sensor.

Regarding Boeing aircraft, the FAA in 2013 proposed a safety directive mandating inspection and possible replacement of angle-of-attack sensors affecting a total of more than 1,000 747 jumbo jets and older 737 models. The agency determined malfunctioning sensors could result in false stall warnings to pilots during takeoffs.

As the latest investigation gains steam, safety experts increasingly are paying attention to the same category of dire consequences that confronted Airbus crews: forceful, automated nose-down commands while flying manually, which can be particularly dangerous if pilots are surprised and confused about how to counteract them.

Some of the data-processing units for angle-of-attack sensors and others measuring airspeed on the Lion Air jet were manufactured by Honeywell International Inc. A spokesman said the company has been contacted by the National Transportation Safety Board and is cooperating. The probe is expected to examine whether possible problems with those units may have contributed to the crash.

The sensors themselves were supplied by a United Technologies Corp. unit, which didn't respond to a request for comment.

Introducing new systems, even those meant to enhance safety such as the MAX 8's stall-protection features, can come with pitfalls as teething difficulties are addressed, according to safety experts.

When a previous upgrade to Boeing's 737 plane entered service, it also created problems. A British Midland 737-400 crashed in England on Jan. 8, 1989, after an engine failure, killing 47 of the 126 people onboard. Investigators determined new cockpit instruments, though not the cause of the accident, made it more difficult for the crew to manage the situation. They recommended enhanced training for pilots.

"The challenge for manufacturers is to introduce the sorts of technology which have made aviation as safe as it is" while simultaneously "minimizing the conversion training that is required to fly different aircraft of the same family," said Graham Braithwaite, who teaches safety and accident investigation at Britain's Cranfield University.

--Andrew Tangel contributed to this article.

Write to Andy Pasztor at andy.pasztor@wsj.com and Robert Wall at robert.wall@wsj.com

 

(END) Dow Jones Newswires

November 18, 2018 14:35 ET (19:35 GMT)

Copyright (c) 2018 Dow Jones & Company, Inc.

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