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With the flight data recorder found, avoid the rush to premature conclusions in Lion Air crash

written by John Walton | November 2, 2018

Lion Air had 11 737 MAX 8s in its fleet before Monday’s accident.

With divers raising the flight data recorder from the Boeing 737 MAX on Thursday, premature conclusions are already being drawn about the cause of the crash of flight JT610 into the Java Sea shortly after departure from Jakarta this Monday.

Strong currents are reported to have complicated the efforts by divers and remotely operated submersible vehicles to retrieve the recorders.

Pictures from the scene appear to show the cylindrical section of the flight data recorder mostly intact but having detached from the flat horizontal section that links it to the rectangular part. While the section displayed by search and rescue officials appears to have jagged edges, it is unclear as to whether the recorder was recovered intact and then separated during the raising process, or whether it came apart in the crash.

It is also unclear why, contrary to standard protocols, the recorder seems to have been brandished about in the open air by officials rather than being kept underwater. Per the United States National Transportation Safety Board Flight Data Recorder Handbook for Aviation Accident Investigations, paragraph 3.9:

“If the FDR is recovered in water, it shall immediately be packed in water (fresh, if possible) and not be allowed to dry out. Packaging may be accomplished by sealing the recorder (in water) inside a plastic beverage container with silicon adhesive or a similar sealant.”

The US NTSB is assisting in the investigation as the relevant authority from the Boeing jet’s country of manufacture.

The airline also said in a statement that it has followed the direction of Indonesia’s transport ministry and suspended its maintenance and engineering director. Lion Air is also reported to have suspended two further staff members: the fleet maintenance manager and the engineer releasing the 737 MAX this past Monday. Lion Air will also be subject to between three to four times more on-ramp inspections, according to transport minister Budi Karya Sumadi.

The ministry also required both Indonesian Boeing 737 MAX operators, Lion Air and Garuda Indonesia, to perform what it called “special” airworthiness inspections on their MAX fleets.

Australia’s government, meanwhile, has maintained its interdiction on staff and contractors using Lion Air, and has expanded its ban to Lion Air’s international subsidiaries, with the Department of Foreign Affairs and trade noting on its Smartraveller website:

“Following the fatal crash of a Lion Air plane on 29 October 2018, Australian Government officials and contractors in Indonesia have been instructed not to fly on Lion Air or its subsidiary airlines that operate outside of Australia. This decision was made in light of responsibilities for the work health and safety of staff. This decision will be reviewed when the findings of the crash investigation are clear. Australian travellers should make their own decisions on which airlines to travel with.”

The remains of one female passenger, Jannatun Shintya Dewi, have been identified by the Disaster Victim Identification team of the Indonesian police force and released to family members by authorities, Lion Air said in a statement on Thursday. Dozens of bags of further remains have been passed to a police hospital in East Jakarta.

Premature conclusions are being drawn from the ADS-B data

With the pressure of the 24-hour news cycle, the usual round of experts — self-acknowledged or otherwise — claiming to have figured out what happened to flight JT610 have been doing the rounds.

Many premature conclusions have been drawn from the speed and altitude data transmitted from the aircraft via its ADS-B transponder. Those data were then collected and processed by companies including FlightRadar24 and Plane Finder. These systems and datasets come — or should come — with substantial accuracy warnings, and in fairness the more reputable providers, often used by airline operations centres and for other industry functions, are very clear about this.

First, the data sets transmitted reflect the information from the aircraft’s systems, which may or may not have been an accurate reflection of the actual situation. To perhaps oversimplify, if an aircraft’s sensor was reporting X, but the reality was Y, X would have been broadcast via ADS-B.

The amount of data and indeed the amount of sources of data transmitted via ADS-B are also substantially smaller when compared with that contained within the flight data recorder. Further data will also come from other sources, including ground-based radar, and hopefully in due course from the cockpit voice recorder.

“ADS-B stands for Automatic Dependent Surveillance – Broadcast. Automatic because it requires no input from the flight crew; Dependent as it depends on the aircraft’s navigation system for data. ADS-B is a standard for broadcasting flight parameters via an aircraft’s transponder that will be augmenting or replacing secondary surveillance radar in the coming years,” FlightRadar24 told Australian Aviation in a statement.

“ADS-B data is incredibly useful as it can tell us many things about a flight. In this case, the location data combined with the last reported altitude provides a narrow search area. The altitude changes over time give us an indication of steep descent. But the data that is part of ADS-B is not inclusive of all parameters recorded by an aircraft’s flight data and cockpit voice recorders and, importantly, the data cannot tell us why an event occurred. There may be multiple explanations for any given set of data and it is the task of investigators to determine what the totality of evidence – including ADS-B, data recorders, and physical evidence – says is the cause of the accident,” said FlightRadar24.

In this case, the company explained, “Flightradar24 received ADS-B signals from the aircraft’s transponder that included the aircraft’s Mode S address (sometimes referred to its hex address), the callsign (LNI610), latitude and longitude per report, calibrated altitude in feet above mean sea level, the aircraft’s ATC assigned squawk code, ground speed (in knots), track (the direction of travel), and vertical speed (in feet per minute).”

Yet headlines such as “Did a Small Metal Tube Bring Down an Indonesian Airliner?” (The New York Times) and “Doomed Lion Air Boeing Jet Had Airspeed Failure on Prior Flight” (The Japan Times) jump to conclusions that the aircraft’s pitot tubes may be a contributing factor.

The 737 MAX’s pitot tubes, which are understood to be manufactured by UTC Aerospace Systems, part of mega-supplier United Technologies Corporation, do not seem markedly different from those used on the 737 NG. UTC did not respond to requests for confirmation and details on the matter, stating “We are deferring all media inquiries to Boeing at this time.” Boeing did not respond to requests.

In any case, issues with pitot tubes generating inaccurate data are not new. A spate of issues in the early part of this decade caused Boeing to implement a wiring change in early 2014, and experienced pilots – Lion Air stated its captain had more than 6,000 flying hours and its first officer more than 5,000 – are not unfamiliar with the problems and resulting issues such as airspeed disagree notifications.

Malindo Air first Boeing 737 MAX 8, 9M-LRC. (Boeing)
Lion Air subsidiary Malindo Air was the first airline to take delivery of a 737 MAX. (Boeing)

Air crashes in our modern era are unprecedentedly few and far between, and the aviation industry’s ongoing focus on safety, especially learning from every incident, requires professional investigators who are free from any pressure to produce quick answers in impracticably short timeframes.


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