Crash: Lion B38M near Jakarta on Oct 29th 2018, aircraft lost height and crashed into Java Sea, wrong AoA data
Bron : The Aviation Herald (http://avherald.com/h?article=4bf90724&opt=0)
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Indonesia's Ministry of Transport reported a tug boat saw an aircraft crash into the Java sea.
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On Oct 31st 2018 a local fisherman reported they (he and his friends) were out on the Java Sea to fish for shrimps when they observed a white airplane with an orange pattern in some distance, the aircraft was flying unusually low. The aircraft appeared to roll in for a turn when it shook and swooped sharply and impacted the waters of the sea. Immediately after a sound of thunder or explosion occurred. They were afraid of approaching the source of the sound and decided to return to the coast which was about 3 hours away. After arriving at the coast they saw the coast was crowded with many residents looking out over the waters, there were emergency vehicles and policemen in the crowd. They talked to a policeman and told him about their observation, police asked them to show them the crash site. After a trip of about 3 hours back to the location they found debris, body parts and oil slicks on the surface of the water. Soon after many more ships arrived at the scene.
On Nov 5th 2018, following the KNKT release confirming airspeed indicator problems during the last 4 flights of the aircraft, a tweet posted on Oct 29th 2018 at 07:07Z by Razaan Botutihe gained sufficient weight to be rated as factual. The tweet states concerning flight JT-43 from Denpasar (Indonesia) to Jakarta, the last flight the aircraft completed: "Airspeed unreliable and alt disagree shown after take off. STS was also running to the wrong direction, suspected because of speed difference. Identified that CAPT instrument was unreliable and handover control to FO. Continue NNC of Airspeed Unreliable and ALT disagree." (Editorial Notes: STS: speed trim system. As far as is known so far the accident crew managed to control the aircraft for 12 minutes from takeoff to maintaining 5000 feet at about 290-310 knots over ground between 5000 and 5400 feet, which suggests they were flying on pitch and power for that time, it thus appears something beyond unreliable airspeed and altitude must have contributed to the loss of control in minute 13.) In addition three different versions of a maintenance logbook were leaked to the Internet, after a closer look they all appeared to show the same log book at different point in time. Apart from the remark of unreliable airspeed and altitude, which prompted the flushing of the captain's static ports, an entry for elevator feel computer light illuminated was written down by the flight crew of JT-93 (presumably a typo and believed to be JT-43), maintenance opened and cleaned a cannon plug connector for the elevator feel computer, checks by the Aviation Herald with AMEs and related Maintenance Manuals confirmed the log book appeared authentic, the maintenance activity concerning that plug however could not have changed the forces on the pitch control of the yoke, only the status and error messages concerning the system could have been affected by the maintenance activity. The elevator feel computer has its own static and dynamic ports positioned at the tail of the aircraft, is purely mechanical with no electronic components except for some status monitoring, depends on hydraulic systems A and B available and does not depend on the instrumentation/Air Data References used for pilot instrumentation.
According to ADS-B data transmitted by the aircraft's transponder the aircraft departed Jakarta's runway 25L at 06:21L (23:21Z Oct 28th), never climbed above 5400 feet remaining between 5200 and 5400 feet for about 6 minutes before losing altitude and disappearing from radar about 12 minutes after departure at about 06:33L (23:33Z) about 35nm northeast of Jakarta's International Airport.