The National Transportation Safety Committee's report into the crash said the pilots' lack of knowledge of the flight control system coupled with maintenance problems were crucial to the tragedy, reports Efe news.
The accident killed all 198 people onboard in October 2018, when flight JT610 plunged into the Java Sea shortly after taking off from Jakarta.
"The investigation considered that the design and certification of this feature was inadequate," the report read, referring to the Maneuvering Characteristics Augmentation System, (MCAS).
The MCAS is an anti-stall feature Boeing introduced on its new model that automatically activates when it detects the aircraft flying at a high pitch (angle of attack) and low speed to prevent it from stalling.
The system pushes the plane's nose down, causing it to gain speed and escape the aerodynamic stall.
However, the MCAS was designed to operate on a single angle of attack sensor - which malfunctioned and activated the feature after sending it erroneous data.
Pilots, who were unaware of the problem, reportedly attempted to counteract the system more than 30 times before losing control of the plane.
"Boeing assumed that MCAS' dependence on a single sensor was sufficient to comply with certification requirements. We believe this system is vulnerable," Nurcahyo Utomo, the committee's investigator said at a Friday press conference.
The report concluded that the US' Federal Aviation Administration (FAA), which certified both the MAX's design and the MCAS feature, based its decision on incorrect assumptions.
In March, a second accident involving a MAX airplane in Ethiopia killed 157 people in circumstances similar to those of the Lion Air crash, grounding the model to this day and plunging Boeing into an unprecedented delivery crisis.
( With inputs from IANS )