In the era of deep fakes, hacked and forged documents, impersonations and phishing attacks, an eye of skepticism is an essential digital tool in the modern media era.
Lion Air 610’s crash off the coast near Jakarta on Monday morning (local time) has sparked the requisite investigation to find the cause of the first accident involving a recently-delivered Boeing 737 Max 8. Almost immediately, documents began circulating in the aviation community that appeared to be a page from the airline’s Aircraft Flight & Maintenance Log from the flight that immediately preceded JT610.
The first version document that shared with The Air Current appears to detail the trip from Denpasar to Jakarta aboard the three-month old PK-LQP. The image’s annotations point to an altitude disagreement seen by the crew just after takeoff, but the hand drawn blue circles obscure key parts of the document. Simply put, an inadvertently redacted document doesn’t give the full picture of the aircraft’s most recent maintenance.
A second version of the same image was reviewed by The Air Current several hours after the crash. This one lacks the annotations, providing a clearer view of the “discrepancies/malfunctions” column of the page. JT43 experienced both and airspeed and and altitude disagreement after it left Denpasar and the crew witnessed the illumination of the “FEEL DIFF PRESS LIGHT” indication, which lights up if it senses a difference in pressure from A and B system to the Elevator Feel and Centering Unit and can reflect a change in the normal controllability of the aircraft. According to Flightradar24 tracking, JT43 made the trip at 28,000 feet.
NOTE: Explanation of FEEL DIFF PRESS has been updated.
Now, a third version of the log has surfaced. This one includes all the elements of the second, but the document was photographed displayed on another screen, a curved-edge mobile phone. UPDATE: A higher-resolution version of the third version of the log document has been uploaded here and reflected in the description below.
The handwriting and signatures match the first two documents, but it now includes a filled out corrective action section and an attached narrative of JT43 appended to the shared image. STS system identified here is the Speed Trim System.1According to the 737’s documentation, the STS is “An electrical stabilizer trim input automatically controls certain aircraft attitude conditions when undergoing large thrust changes in the lower speed region, such as takeoff and go-around. These conditions require high thrust settings and are especially present with a low weight aircraft and a relatively aft center of gravity where the aircraft wants to “nose up”. The STS supports the crew during these conditions when manually controlling the aircraft without the use of an autopilot by an opposite stabilizer trim, commanding a nose down force by use of the autopilot trim.
A: PK LQP, B737 Max 8
O: Airspeed unreliable and altitude 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 Non normal checklist of Airspeed Unreliable and Altitude disagree. Decide to continue flying to CGK at FL280, landed safely rwy 25L
R: DPS CGK LNI 043
This narrative from JT43 isn’t actually written on the document, which appears to detail what maintenance actions were performed on the LH pitot and static air data modules. A higher-resolution version of the document circulating lists the corrective action taken on the air data module (ADM), which was flushed and was tested “on ground found satisfied.” A second test of the elevator feel computer was tested and “found ok.” as well.
The air data system will no doubt be a focus of the crash, but social media has presented users with three versions of the same document at three different states of modification. As the investigation gets rolling in Indonesia and the aircraft maintenance logs from JT43 and other earlier flights are scrutinized, there is a real peril of drawing speculative conclusions or forming narratives with leaked documents that appear to change with every additional round of sharing.
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