Officials investigating the deadly crash of Ethiopian Airlines Flight 302 have said this morning that the plane suffered from “repetitive uncommanded nose-down” prior to crashing, in an apparent reference to the Boeing aircraft’s controversial automated flight control system. Officials also said that the plane had not been damaged by a foreign object, and stressed that the plane’s pilots followed the correct procedures, but could not prevent the 737 Max 8 from crashing.

“The preliminary report clearly showed that the Ethiopian Airlines Pilots who were commanding Flight ET 302/10 March have followed the Boeing recommended and FAA approved emergency procedures to handle the most difficult emergency situation created on the airplane,” reads a statement from Ethiopian Airlines. “Despite their hard work and full compliance with the emergency procedures, it was very unfortunate that they could not recover the airplane from the persistence (of) nose diving.”

Ethiopian officials have asked Boeing to review the 737 Max’s flight control system as a result. A full report into the crash of Ethiopian Airlines Flight 302 will be released in about one year.

Investigators are zeroing in on the controversial automated flight control system as the primary cause

By ruling out other causes, today’s briefing suggests that investigators are zeroing in on the controversial automated flight control system as the primary cause of the March 10th crash that killed all 157 people on board. The same anti-stall software has been cited as contributing to the October 29th crash of another Boeing 737 Max airplane, Lion Air Flight 610, which also killed everyone on board.

Not only was the Maneuvering Characteristics Augmentation System, or MCAS, engaged on the Boeing 737 Max jet that crashed minutes after take-off in Ethiopia, but it re-engaged up to four times, according to The Guardian. The system automatically points the nose of the aircraft down to prevent a perceived stall-out. In the case of Lion Air 610, a faulty sensor sent the signal that the plane was climbing too steep and in danger of stalling.

These are the only two accidents involving the new Boeing 737 Max series of aircraft, which was first introduced in 2017. Since the crash of Ethiopian Airlines 302, more than 300 Boeing 737 Max passenger jets have been grounded worldwide.

Boeing began rolling out an update to its MCAS software soon after the Lion Air crash. But this week, the company said the update was delayed. Boeing had hoped to submit the update to the Federal Aviation Administration as early as this week. The FAA must approve the new software and training procedures before the Max can return to commercial flight. The update could come , according to The Wall Street Journal, with final FAA testing to take an additional six weeks. Overseas regulators could take even longer to review and certify the fix.

Meanwhile, lawmakers and prosecutors in Washington, DC, are trying to determine if there was any wrongdoing in the approval and certification of Boeing’s MCAS software. The Senate Commerce Committee is investigating whistleblower allegations about improper training and certification for FAA safety inspectors. Subpoenas have been issued in a criminal investigation into the FAA’s certification process, which reportedly was mostly outsourced to Boeing engineers.