But in the circumstance of AirAsia 8501, there is more to the story that led to the crash into the Java Sea, killing all 162 people on board in December 2014.
First, it is important to understand the sequence of events that led to the accident.
1. A mechanical failure involved with limiting deflection of the rudder (the vertical flight control on the tail of the airplane that assists in turning the airplane) occurred.
2. This mechanical failure had occurred on the ground and in-flight on previous occasions at least 23 times. Although maintenance complied with the troubleshooting process with resets and a replacement part, the faulty component, a crack in the electrical soldering, was never repaired.
3. The crew initially responded to the failure with the appropriate actions commanded by the electronic checklist.
4. The indication of this failure happened numerous times with the crew repeating the same checklist items until the captain reset a circuit breaker, an action that was not part of the authorized procedure.
5. Pulling the circuit breaker disconnected the autopilot and induced the failure of a portion of the rudder control system, causing the airplane to bank to the left.
6. The co-pilot who was flying the airplane did not immediately correct the bank to the left.
7. With the airplane in manual control, the co-pilot applied numerous inputs (actions) at the control stick, the worst of which put the nose of the airplane in a very high attitude, causing an aerodynamic stall.
8. Recognizing the seriousness of the situation, the captain applied his own control inputs, which were sometimes opposite that of the co-pilot's. In the heat of the battle, the captain made nonstandard reactionary commands, potentially causing additional confusion.
9. The Airbus A-320 never recovered from the stall and crashed into the Java Sea.
As with all aviation accidents, many factors contribute to crash.
In the case of AirAsia 8501, the mechanical failure of the portion of the rudder system that limits its deflection at higher air speeds was one of the culprits. , Despite the frequent history of this problem on the same airplane, the system unfortunately was not classified as a repetitive item. If it had been classified as a repetitive item, the source of the malfunction might have been repaired.
That being said, the malfunction should not have been serious enough to cause a tragedy, but merely a temporary distraction followed by a slight alteration to the pilot's procedures for the arrival.
Instead, the co-pilot became focused on the problem and was justifiably surprised by the airplane banking on its own after the circuit breaker was pulled; he had a delayed response. The co-pilot probably overreacted to the situation and overcontrolled his manual inputs. If either pilot had known the potential effects of pulling the circuit breaker, certainly they would not have done so.
But why did the captain pull the circuit breaker?
Having experienced the same problem only three days earlier on the ground, a mechanic had performed this action in the process of fixing the problem. Unfortunately, in flight, the airplane reacted differently.
With the airplane disconnected from the autopilot and improper control inputs being applied by the co-pilot, the airplane entered an aerodynamic stall.
Although the captain recognized the situation, it appears that he did not take full control of the airplane away from the co-pilot. Why?
In the stress of the situation, he might have forgotten that the Airbus flight control sidesticks are not mechanically connected. Pilots have no visual or tactile sense of what input the other pilot is applying. A button on the sidestick has to be pressed and held for 40 seconds to take control from one side or the other. This was not done.
In addition, the captain vocalized untypical commands to the co-pilot in an attempt to assist in the stall recovery. The commands were contradictory and confusing. And the stall recovery was not performed as trained, with critical recovery procedures omitted.
All airlines in the U.S. practice recovery techniques from unusual attitudes, commonly referred to as upset recoveries.
AirAsia's attitude was that this type of training was unnecessary because Airbus engineering designs electronic protections to prevent such unusual attitude upsets. But these protections degrade if mechanical malfunctions cause the airplane to enter what Airbus calls "Alternate Law," which is the circumstance faced by the pilots of AirAsia 8501.
At the end of the day, this was a preventable crash. Blaming this accident completely on the pilots will not solve the problem. What will solve the problem are the numerous recommendations given to the airline. Many of these recommendations have already been implemented.
This is an accident from which the entire industry can learn. Let's hope that we in the business heed its warning.