LATEST AIR ASIA 8501 THEORY PREPOSTEROUS
Aviation Attorney Arthur Wolk says a recent emergency airworthiness directive may explain what could have caused crash of AirAsia Flight QZ8501.
The latest word from the Government of Indonesia is that the cause of the crash was entry into a thunderstorm that resulted in so much ice accumulations that one or more engines failed and the airplane stalled.
Any ice accumulation sufficient to shut down one of these engines would literally have to be so large that it covered the entire engine inlet. The aircraft is equipped with inlet heat to prevent just such an accumulation which has never happened even without inlet heat. The inlet is about 6 feet around.
Large ice accumulations if the heat was off could cause foreign object damage to an engine but it would take far more than one engine being damaged to cause the loss of this airplane.
Loss of an engine simply means the crew must descend to a lower altitude but this crew ascended so power was available and thus the engine didn’t fail.
An aerodynamic stall that apparently is misunderstood by the Government official is also virtually impossible due to a single engine failure.
The remaining engine has more than enough power to maintain flight albeit at a lower altitude.
The Emergency Airworthiness Directive issued December 10th says that ice can prevent angle of attack sensors from operating, pitch the airplane nose down and prevent the sidestick controllers from allowing the crew to pull out of a dive. That scenario is far more likely as is a breakup due to turbulence.
If the pitot tubes used to provide airspeed data to the computers iced up, the aircraft can stall due to misinformation provided to the flight control system.
The current theory appears to be generated from industry representatives attempting to establish pilot error as the cause rather than airplane defect. That undue influence on investigators happens all the time.
If they don’t figure out or disclose or fix how the airplane’s computer architecture contributes to these accidents, they will continue to occur.
The weather was bad, and perhaps the crew should have refused to take the flight but Airbus needs to be transparent about how pilots need to have the last word how the airplane operates not the computers that interface with them.
Arthur Alan Wolk
January 4, 2015