As the Air Asia Indonesia accident investigators confirm the crash was caused by loss of control following an electrical snag, the tally of people who have died unnecessarily on commercial airliners has taken another step up.
There have now been 18 loss of control accidents since the year 2000, and 1,886 people have died in them because the pilots failed to maintain control of aeroplanes that were completely flyable, and most of which had nothing wrong with them.
The Air Asia accident involved an Airbus A320 at 32,000ft in the cruise over the Java Sea last year on 28 December 2014. The report says an electrical fault – known to the airline and the captain but not resolved – caused an alert to be repeated three times before the captain attempted to resolve the issue by tripping and resetting the circuit breakers for the flight augmentation computers.
The autopilot had been coping with the control effects of the electrical fault, but when the FACs were switched off the autopilot tripped out and left the pilots to fly the aircraft, and they clearly were not ready for that.
The electrical fault was caused by a crack in the solder on a printed circuit board associated with the rudder travel limiter, which prevents the rudder being deflected too far at high speeds. As soon as the autopilot was disconnected, the effect of the fault was to offset the rudder by 2deg, which is not much, but enough to cause the aircraft to roll left to a bank angle of 54deg. Most airliners bank about 20deg (maximum 30deg) for ordinary manoeuvres on commercial flights.
The copilot was flying, and he failed to take action immediately to roll the wings level, so the nose dropped. Some 9sec later when he did roll the wings almost level he also pulled the nose up. Then the bank angle returned to 53deg left, and the pull-up demand on the copilot’s sidestick moved to maximum, actions that suggest the copilot was already seriously disorientated. The aircraft climbed to a maximum height of 38,500ft, stalling on the way.
Once stalled, it descended at a rate of 20,000ft/min into the sea.
The pilots never recovered from the stalled condition. As in the AF447 tragedy the copilot’s nose-up demand – the opposite of what was required to regain control – continued.
There is some evidence that the captain may have left his seat to trip the FAC circuit breakers. At one point in this upset he gave the copilot the confusing instruction to “pull nose-down” (the pilots were different nationalities and neither was a native English speaker), but he then failed to act correctly to take override control with his sidestick.
The industry knows it has this huge weakness in its pilot workforce. The death of 1,886 people since 2000 testifies to it.
There are various components to the problem:
- highly reliable and accurate automated systems in today’s aircraft mean pilots almost never get the physical or mental exercise of controlling the aircraft and its flight path, so many are not ready when they have to take control;
- statutory recurrent training requirements are out of date and do not relate to the task of today’s pilots in modern cockpits;
- most pilots now have no training for recovering aircraft from upsets involving significant attitude deviations from straight and level;
- most have never handled an aircraft at high level and therefore are not familiar with how small the flight envelope is in thin air, and what to do if the aircraft goes outside the flight envelope (like entering a full stall).
Some airlines, in countries where the aviation authorities allow advanced airlines to vary their training according to evidence of need, the carriers are dealing with this weakness.
But in others where the old recurrent training requirements still dictate training minimums, airlines are still working to the minimums.
And there are even questions about whether, under the stress of aircraft malfunctions or upsets, some pilots’ brains just go all funny and there’s nothing training can do about it. In Toulouse, France, the ISAE is researching this.
Meanwhile, it is a tragedy that, in an industry that is very safe and getting safer, there will inevitably be more of these unnecessary fatal accidents. It only takes the smallest snag to trigger one.