October 29, 2019 marks the Lion Air Crash one year later. This is a look back at the disaster and what we have learned since then.
The Boeing 737 Max aircraft operated by Lion Air crashed less than fifteen minutes after takeoff from Soekarno-Hatta International Airport in Jakarta. I previously blogged about the incident at Doctor Aviation.
What Happened That Day
The Business Insider recently released a timeline of event for the crash. I recommend reading through the timeline. What becomes clear is that the pilots were confused by contradictory flight information from their flight instruments and they were fighting against a system that was designed to help them
The system is known as the MCAS (Maneuvering Characteristics Augmentation System). The system is designed to detect a nose up pitch condition that could cause an aircraft to stall. The system them commands the elevator in the back of the aircraft to rotate upwards, causing the nose to pitch downwards. The primary sensor sending signals to the MCAS is the AOA (Angle of Attack) Sensor. This sensor proved to be faulty on the ill-fated flight.
The Accident Report
The Indonesian government released their report on the accident as we approached the one year anniversary. Not surprisingly, the report highlighted the faulty MCAS and the pilot’s confusion. It also critiqued ground maintenance personnel, the FAA for a lack of oversight and Boeing for inadequate documentation and training for the MCAS, which it states led to pilot confusion.
As a pilot myself, I want to be very careful what I say about the deceased pilots. They “had their hands full” as we used to say in the piloting world. They were fighting the aircraft and trying to remedy the situation. The one suggestion I would have for myself or pilot in this situation is to remember the first step in an emergency situation. Maintain Aircraft Control.
I wish the pilots would have used the outside visual references available in order to help them keep the aircraft flying. It appears that they became fixated in trying to determine which of the contradictory readings they were receiving from the instruments was accurate and trustworthy. Certainly the pilots needed to figure out which, if any, instruments they could believe. However, a pilot’s first duty is to fly the aircraft and that can be done without relying on instruments.
The Swiss Cheese Model
I was fortunate to author a book on aviation mishaps. It is entitled: Controlling Pilot Error: Controlled Flight into Terrain. It is from a series by McGraw Hill and edited by my friend and fellow aviator, Tony Kern. In the Series Introduction Tony highlights what is known as the Swiss cheese model. Picture four pieces of Swiss cheese. The pieces are named:
Preconditions for Unsafe Acts
When the holes in these four pieces of cheese align, a mishap occurs. If the chain of events can be stopped anywhere along the pathway, the mishap is avoided. Unfortunately, in the case of the Lion Air, the Swiss cheese aligned.
What is Next?
Boeing continues to work on a fix to the MCAS problem. They hope to have the fix complete by the end of the year. However, they have missed previous deadline goals already. They have much work to do with engineers and aviators before they can hope to restore the public’s confidence. In the meantime we pause to remember the 189 victims of Lion Air.