Air crash investigators say an altitude sensor was changed the day before a Lion Air plane crashed into the sea, killing 189 passengers and crew.
The night before the crash indicators displayed differences in angle of 20 degrees, but the flight still landed safely.
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Experts say the angle of attack sensor tells the aircraft's computers whether the nose is too high - which can throw the plane into an aerodynamic stall and make it fall.
"The point is that after the AOA [sensor] is replaced the problem is not solved, but the problem might even increase. Is this fatal? NTSC wants to explore this," Transport safety committee chairman Soerjanto Tjahjono said.
Australia's ABC reports Lion Air's previous attempts to fix the sensor had not worked and the sensors had been replaced for the plane's second to last flight.
The pilot's and co-pilot's sensors disagreed on that flight, and the two-month-old plane went into a sudden dive after take-off. The pilots had recovered the jet and continued to fly on to its destination at a lower-than-normal altitude.
Boeing - which made the plane - has issued a safety bulletin reminding pilots how to handle data from a key sensor.