A passenger jet that crashed into the sea near Indonesia last week had an airspeed indicator problem on its final four flights, officials say.
The damage to the device, which tells pilots how fast their planes are travelling, was revealed after the recovery of a "black box" recorder.
Lion Air flight JT 610, carrying 189 people, crashed soon after taking off from Jakarta, the Indonesian capital.
Angry relatives confronted Indonesian officials at a conference on Monday.
They wanted to know why the plane was allowed to fly and demanded there be no let up in recovery efforts. The cause of the crash is still unclear.
"We are the victims here. Imagine if you were in our position," said Najib Fuquoni, a relative of a victim.
At one point, families demanded that Lion Air's founder, Rusdi Kirana, who attended the meeting, stand up.
He did not speak but clasped his hands in prayer and bowed his head.By Theo Leggett, BBC international business correspondent
The suggestion that the Lion Air plane had a defective airspeed indicator is a significant development. The aircraft's erratic behaviour during its final flight, and reports of an issue during a previous journey, had already prompted speculation that this could have been an issue.