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Airspeed Sensors Emerge as Initial Focus in Lion Air Crash

Airspeed Sensors Emerge as Initial Focus in Lion Air Crash B3 CF296 backgr 4U 20181030045631

Potentially faulty or misleading airspeed indications in the cockpit have emerged as an initial focus of safety experts delving into the Lion Air jet crash in Indonesia that killed 189 passengers and crew, according to industry officials tracking the investigation.


, which manufactured the twin-engine 737 Max 8 model and is participating in the probe, has privately suggested to at least one airline official and an outside safety expert its interest in whether the pilots received unreliable speed data, according to people familiar with the conversations.

The plane, which was delivered to the airline in August, plummeted into the Java Sea in good weather 12 minutes after taking off from Jakarta, without the crew sending a mayday message. Indonesian teams on Tuesday were mapping the seabed in their search for the jetliner.

The deadly crash of a Lion Air Boeing 737 aircraft in Indonesia is one of the worst aviation catastrophes of 2018. The WSJ looks at some big questions that have emerged as investigators try to determine the cause of the crash. Photo: AP Images

The Chicago-based plane maker also has signaled, according to one independent safety expert with close ties to the company, that its experts are particularly eager to understand the maintenance work that reportedly was performed on part of the plane’s airspeed-measuring and reporting systems before the fatal flight.


has told at least one airline official it understood an airspeed-monitoring issue was addressed by maintenance the day before the crash, according to a person briefed on the discussion.



spokesman declined to comment, referring to the company’s previous statement that it was providing technical assistance in the probe and directing questions to Indonesian authorities.

Discussions about possible speed discrepancies are preliminary and could change significantly, if data downloaded from flight-data and cockpit voice recorders point to other potential system malfunctions or pilot missteps. Pilots are routinely trained to cope with unreliable airspeed indications, and safety experts said such responses—especially in clear weather with the horizon visible—normally shouldn’t cause crews to lose control.

Still, safety experts said coping with erratic speed displays can be tricky for some aviators because they usually require at least temporary reliance on manual flying, skills that are used infrequently in today’s increasingly automated cockpits.

Indonesian and U.S. government investigators haven’t commented on any details of the probe, and air-traffic control officials have said the flight crew didn’t provide specifics when they requested and received permission to return to the airport.

Airspeed reporting and maintenance issues will be part of the investigative effort, Soerjanto Tjahjono, the head of Indonesia’s National Transportation Safety Committee, which is leading the probe, told The Wall Street Journal without elaborating. He confirmed that investigators will examine circumstances surrounding the specific maintenance checks performed before the crash.

Search at Sea

New Boeing 737 model went missing shortly after takeoff from Jakarta to Pangkal Pinang.


said in a message to carriers operating the latest 737 Max 8 models that it would strive to keep them informed but noted that it “has no recommended operator action at this time,” according to a copy reviewed by the Journal.

Such language typically indicates that a manufacturer hasn’t uncovered any systemic or design deficiencies requiring immediate safety checks or repairs.

A search of Federal Aviation Administration records hasn’t revealed any unusual pattern of problems or failures affecting airspeed indicators or other mechanical or electrical systems on the 737 Max 8 fleet, according to one person familiar with the matter.

A number of other 737 Max 8 operators also said they weren’t aware of any recurring faults with the plane.

But based on public information about Lion Air Flight 610—combined with various types of communications among Boeing, some of its airline customers and outside safety experts—industry officials following the investigation increasingly are interested in what airspeed readings were displayed on cockpit instruments. On Boeing 737 Max 8 aircraft, the captain and co-pilot have separate airspeed displays, and there is an additional standby system.

Relatives Grieve as Indonesia Responds to Jetliner Crash

Underwater locators to be sent to crash site will try to find plane’s flight-data and cockpit-voice recorders

Search and rescue team members in Jakarta look through recovered belongings believed to be from the downed Lion Air flight JT610 on Tuesday.

edgar su/Reuters

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The Transportation Ministry has ordered the two Indonesian airlines flying the Boeing 737 Max 8, Lion Air and flag carrier

Garuda Indonesia

to report on any repetitive airspeed indication problems and explain any procedures they use to fix them. The planes won’t be grounded and will remain in service, Pramintohadi, the acting director-general for air transportation, told reporters.

Problems with malfunctioning pitot tubes—airspeed sensors located under the noses of aircraft—have been well documented over the years and resulted in a number of high-profile passenger-aircraft accidents. They often occur in stormy weather at cruising altitudes—much higher than the Lion Air plane, which didn’t climb above 5,000 feet—because ice crystals can accumulate and plug sensors.

In the past decade, U.S. and European regulators have issued a series of mandatory safety fixes to check or swap out trouble-prone pitot tubes on various

Airbus SE

jetliners and other models.

But the same sensors also can be affected by residue or other circumstances on the ground. Pilots have noted instances of wasp nests inside pitot tubes, and workers have mistakenly left covers on them after painting or maintenance.

“A number of things can go wrong with this system, even though it is pretty simple,” said one pilot for a major U.S. airline.

Write to Andy Pasztor at [email protected], Andrew Tangel at [email protected] and Robert Wall at [email protected]

Source : WSJ

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