According to a report published on Wednesday by The Wall Street Journal quoting sources close to United States officials’ early assessment of evidence, the black box audio recording of the last conversation between the two pilots indicates that the captain might have turned off the switches controlling the flow of fuel to the plane’s engines.

The U.S. Federal Aviation Administration and Boeing have privately issued notifications that the fuel switch locks on Boeing planes are safe.

The Federal Aviation Administration (FAA), back in 2018, had flagged the potential disengagement of the fuel control switch locking feature on certain models of Boeing aircraft, including 787s and 737s.