JAKARTA, Indonesia - A Lion Air flight that crashed into the sea off Indonesia during a one-hour journey from the Indonesian capital of Jakarta to the western city of Pangkal Pinang on October 29, left all 189 people on board dead.
Now, nearly a month after the tragic crash, Indonesias transport safety committee (KNKT) has released its preliminary report into the crash, concluding that the Lion Air Jet that crashed, was not in an airworthy condition on its second-to-last flight.
According to KNKT investigator Nurcahyo Utomo, the agency had investigated the airlines maintenance practices and pilot training and a Boeing Co anti-stall system as part of the preliminary probe.
KNKT's report claims that on its penultimate flight, pilots of the jet experienced similar problems that those on its doomed last journey faced.
The report explained that pilots flying the same plane a day earlier had experienced a similar problem, en route from Denpasar, Bali to Jakarta.
The report noted that pilots on the flight then used switches to shut off the system and used manual controls to fly and stabilize the plane.
The investigating committee explained in the report, "The flight from Denpasar to Jakarta experienced stick shaker activation during the takeoff rotation and remained active throughout the flight. This condition is considered as un-airworthy condition and the flight should have been discontinued."
According to investigators, upon landing, pilots of that flight had reported problems to Lion Airs maintenance team.
While the maintenance team is said to have checked the jet after the complaint was received, they cleared it for take-off the next morning.
Investigators said that the after the crash in October, Lion Air instructed pilots to provide a full comprehensive description of technical defects to the engineering team.
However, KNKT did not provide a cause for the crash and said that investigators had not determined if the anti-stall system was a contributing factor.
Boeing's anti-stall system was not explained to pilots in manuals.
Utomo told reporters, We still dont know yet if it contributed or not. It is too early to conclude.
Meanwhile, Boeing issued a statement arguing that all the procedures for preventing an anti-stall system activating by accident were already in place.
The plane manufacturer pointed out that pilots of the penultimate flight had used that drill.
However, while Boeing detailed the airline maintenance actions that were set out in the report in its own statement, the company has not blamed ground workers or pilots for the accident.
According to U.S. pilots and Indonesian investigators, a revised anti-stall system that was introduced on the 737 MAX was missing from the operating manual.
According to Boeing, the procedure for dealing with a so-called runaway stabilizer had not changed between the earlier version of the 737 and the newly delivered 737 MAX even though pilots have argued that the control column behaves differently in certain conditions.
Meanwhile, the KNKT report also revealed previously unknown details about the efforts employed by pilots on the doomed flight, to steady the jet.
Pilots were revealed to have reported a flight control problem."
The captains last words to air traffic control were asking to be cleared to five thou or 5,000 feet.
According to the Indonesian investigators, they had retrieved information from the flight data recorder, which showed that the stick shaker was vibrating the captains controls and had been warning of a stall throughout most of the flight.
Further, the black boxes revealed that the captain had been using his controls to bring the planes nose up, however, an automated anti-stall system was pushing it down.
Meanwhile, KNKT confirmed that the search for the cockpit voice recorder (CVR) is still ongoing and investigators are hoping to understand what the pilots discussed and what procedures were carried out before the flight crashed.