American Airlines pilots confronted Boeing about potential safety issues in its 737 Max planes in a meeting last November, US media are reporting.
They urged swift action after the first deadly 737 Max crash off Indonesia in October, according to audio obtained by CBS and the New York Times.
Boeing reportedly resisted their calls but promised a software fix.
But this had not been rolled out when an Ethiopian Airlines’ 737 Max crashed four months later, killing 157 people.
Currently 737 Max planes are grounded worldwide amid concerns that an anti-stall system may have contributed to both crashes.
Boeing is in the process of updating the system, known as MCAS, but denies it was solely to blame for the disasters.
In a closed door meeting with Boeing executives last November, which was secretly recorded, American Airlines’ pilots can be heard expressing concerns about the safety of MCAS.
Boeing vice-president Mike Sinnett told the pilots: “No one has yet to conclude that the sole cause of this was this function on the airplane.”
Later in the meeting, he added: “The worst thing that can ever happen is a tragedy like this, and the even worse thing would be another one.”
The pilots also complained they had not been told about MCAS, which was new to the 737 Max, until after the Lion Air crash off Indonesia, which killed 189.
