An optional warning light could have alerted engineers about mechanical faults on Lion Air's Boeing 737 MAX jet that crashed last month, experts said, sparking an industry debate over whether installing the system should become mandatory.
Lion Air did not install the AOA DISAGREE alert, which warns pilots when the "angle of attack" (AOA) readings do not match, because it is optional and not required by regulators, Managing Director Daniel Putut told Reuters.
The angle is a key flight parameter that must remain narrow enough to preserve lift and avoid an aerodynamic stall.
A faulty AOA reading led the doomed Lion Air jet's computer to believe it was stalled, prompting the plane's new anti-stall system, called the Maneuvering Characteristics Augmentation System (MCAS), to repeatedly push down the nose.
That made it harder for pilots to control the Boeing jet which crashed on Oct. 29, killing all 189 people on board, Indonesian investigators told parliament last week.
"In retrospect, clearly it would have been wise to include the warning as standard equipment and fully inform and train operators on MCAS," said Clint Balog, a professor at Embry-Riddle Aeronautical University.
"I expect you will see this warning included in future MAX production and retrofitted into already delivered MAX aircraft."
Boeing and the U.S. Federal Aviation Administration (FAA) made the AOA alert an optional feature for the 737 MAX, meaning it was not deemed critical for safe operation.
The FAA has said it will continue to participate in Indonesia's investigation into the Lion Air crash and take further action if needed based on findings from the probe.
Indonesia's civil aviation regulator said it would follow the FAA's lead as to whether the AOA DISAGREE alert should be made mandatory for local airlines.