Air velocity sensors emerge as initial focus in Lion's plane crash
Air velocity sensors emerge as initial focus in Lion's plane crash
Potentially defective or deceptive airspeed indications in the cockpit have emerged as an initial focus of safety experts entering the Lion Air. Plane crash in Indonesia that killed 189 passengers and crew., according to industry officials tracking the investigation.
, who manufactured the 737 Max 8 model of two engines and is participating in the probe, has privately suggested at least one airline officer and an external safety expert interested in knowing whether the pilots received speed data. reliable, according to people familiar with the conversations. .
The plane, which was delivered to the airline in August, collapsed in the Java Sea with good weather 12 minutes after taking off from Jakarta, without the crew sending a Mayday message. The Indonesian teams on Tuesday drew seafloor maps in their look for the passenger plane.
The Chicago-based aircraft maker has also pointed out, according to an independent security expert with close ties to the company, that its experts are particularly anxious to understand the maintenance work reportedly done in part of the systems. of measurement and information of the speed of the plane before The fatal flight.
He has told at least one airline official that he understood that a problem of aerodynamic speed monitoring was addressed by maintenance the day before the accident, according to a person informed about the discussion.
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the spokesperson declined to comment, referring to the company's previous statement that he was providing technical assistance in the investigation and addressing questions to the Indonesian authorities.
Discussions about possible speed discrepancies are preliminary and could change significantly, if data downloaded from cockpit voice recorders and flight data point to other possible system failures or pilot errors. Pilots are routinely trained to deal with unreliable airspeed indications, and safety experts said such responses, especially in clear weather with the visible horizon, should not normally cause crews to lose control.
Still, security experts said that dealing with erratic speed screens can be tricky for some aviators, since they generally require at least a temporary dependency on manual flight, skills that are used infrequently in increasingly automated cabins. .
Indonesian and US government investigators have not commented on the details of the probe, and air traffic control officials have said that the flight crew did not provide specific details when they requested and received permission to return to the airport.
Soejanto Tjahjono, the head of Indonesia's National Transportation Security Committee, who heads the investigation, told The Wall Street Journal that there were no further details. He confirmed that the investigators will examine the circumstances surrounding the specific maintenance checks made before the accident.
Search in the sea
The new model Boeing 737 disappeared shortly after the takeoff from Jakarta to Pangkal Pinang.
Boeing said in a message to operators operating the last 737 models of Max 8 that it would endeavor to keep them informed, but noted that "there is no action recommended by the operator at this time," according to a copy reviewed by the Journal.
Such language generally indicates that a manufacturer has not discovered any systemic or design deficiency that requires safety checks or immediate repairs.
A search of the records of the Federal Aviation Administration has not revealed any unusual pattern of problems or failures that affect the airspeed indicators or other mechanical or electrical systems in the fleet of 737 Max 8, according to a person familiar with the matter. .
Several other 737 Max 8 operators also said they were not aware of any recurring failure with the plane.
But based on public information about Lion Air flight 610, combined with several types of communications between Boeing, some of its airline customers and external security experts, industry officials following the investigation are increasingly interested in knowing what airspeed readings are displayed on the cockpit instruments. In the Boeing 737 Max 8 aircraft, the captain and co-pilot have separate aerodynamic speed displays, and there is an additional standby system.
The Ministry of Transport has ordered the two Indonesian airlines that fly the Boeing 737 Max 8, Lion Air and the flag carrier.
to report on any repetitive airspeed indication problem and explain the procedures they use to solve them. The planes will not be on the ground and will remain in service, reporters Pramintohadi, the acting general director for air transport, told reporters.
Problems with poorly functioning Pitot tubes (airspeed sensors located beneath the noses of aircraft) have been well documented over the years and have led to a series of passenger and aircraft accident accidents. High profile. They often occur in stormy climates at cruise altitudes, much higher than the Lion Air aircraft, which did not rise above 5,000 feet, because ice crystals can build up and clog the sensors.
In the last decade, US and European regulators have issued a series of mandatory safety corrections to review or change pitot tubes prone to problems in several
Jetliners and other models.
But the same sensors can also be affected by debris or other circumstances in the soil. Pilots have noticed cases of wasp nests inside the pitot tubes, and workers, by mistake, have left them covered after painting or maintaining.
"Some things can go wrong with this system, although it's quite simple," said a pilot of a major US airline.
-Ben Otto contributed to this article.
Write to Andy Pasztor in andy.pasztor@wsj.com, Andrew Tangel in Andrew.Tangel@wsj.com and Robert Wall in robert.wall@wsj.com
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