|
All accidents are a chain of events that join together and lead to the unfortunate event. Break any link in that chain and the accident can be averted. Basic Human Factors.
1. The crew was aware of the weather ahead and they knew that they couldn't fly over it due to unusually warm temps making the fully loaded A330 unable to climb higher then 37,000 ft. Also, the crew had the radar settings wrong to accurately see the extent of the weather ahead. (if they had the radar set properly, they would have seen how bad the weather was and possibly diverted around it)
2. The captain left the cockpit and relinquished control of the aircraft to the cruise pilot even though he knew there was weather ahead. At the very least he should have waited until they came to the area of concern and seen that everything was OK before going for his rest.
3. When the auto-pilot first disconnected, the pilots failed to do the number one thing they should have in ANY situation... Fly the Airplane! Pilots get drilled again and again in SIM to take over and fly the airplane when something happens. The PNF (pilot not flying) is then supposed to assess the situation and try and correct it, while the PF flies the airplane in full instrument flight rules mode, crosschecking the instruments constantly.
4. Nobody called for the Captain after the auto-pilot disconnected - WTF?! One really low exp pilot and one so-so exp. pilot in a situation and they don't think to chime the cabin and get the captain back up?
5. The stall warning was ignored, possibly due to sensory overload by the two pilots. I feel Airbus is one of the worst airplane makers in regards to ergonomic design of their cockpits and the way warnings are done. They just feed too many sounds and have too many warning lights and the pilots get overwhelmed. Boeing, on the other hand, believes in a dark cockpit philosophy. When things are normal, their cockpits are almost totally dark and quiet. Warnings are very muted unless it's critical and when you hear a warning, you notice it right away.
6. The FO, who was more experienced then the cruise pilot, should have taken control as soon as they started loosing it. Instead, he waited until way too late to finally take over, even though the cruise pilot was holding the aircraft in a full out high altitude stall. Both pilots completely failed to fall back on training skills by not recognizing what was happening and not reacting to the Stall warning by lowering the nose of the aircraft. Why did they keep pulling back? They were at 37000'... they had lots of altitude to play with. It's not like they were at low altitude and had to be concerned about terrain. Also, jetliners at that altitude are super sensitive to airspeed. They really are flying at the bleeding edge of performance and at cruise altitude, the margin for error is very narrow and the speed that they can stall is actually much greater at 40,000 feet then when they are down low. Don't ask me why... school was a long time ago and mach theory gives me a headache, lol. But suffice to say that even letting your speed drop a little at such a high altitude can risk a high speed stall very easily. One can only speculate on why these pilots forgot that simple rule. Altitude is controlled by engine power and airspeed is controlled by aircraft attitude. That's a universal theory that applies to all aircraft, big or small.
7. As the plane fell, the ambient air temperature increased and the pitot tubes finally cleared and the airspeed started to work again. The crew could have re-engaged the autopilot at this time and that might have just saved them.
8. They lost both primary airspeeds and yet neither pilot mentions cross-checking with other instruments to try and determine their speed. There should have been an emergency airspeed indication somewhere (usually a multi-purpose display that has a back up horizon, altimeter and airspeed tape all on one instrument and is completely self contained) Also, they would have had true airspeed indication from their FMS system. That's the computer that controls their flight planned route. Unlike the pilot's main instruments, which use various external sensors, the FMS mainly uses what's called an IRS to navigate with. The IRS is a black box full of laser gyros and accelerometers and it is a totally self contained navigation system. If you lost everything, these boxes would still allow an aircraft to fly around the world and be accurate to within about 1/2 mile after getting there. On the FMS displays there is ground speed and True Air Speed which these pilots could have referenced when the lost the primary instruments. Also, they had another option of calling ATC and asking for their airspeed from the controller since that is data that ATC has from the aircraft's transponder return.
All in all, this was a disaster that never should have happened and I can only imagine the law suits that will come. Months ago, I was upset when I saw the pilot's unions trying to blame the pitot tube manufacturers. I was very happy that the black boxes were finally recovered because they showed just what a goat Phuck the crew response was to what should have been a minor system malfunction. You fly an aircraft into heavy icing conditions at 37,000 feet when there's an abnormal temperature inversion and you'll ice things up... heaters or no heaters. I've seen 2 inches of ice form on engine fan blades after only 15 minutes of flight through weather like that.
I also experienced a loss of both airspeed indicators just a few months ago in one of our planes. I suspected that either a static discharge or maybe a lightening strike caused a power surge that scrambled the data bus on the aircraft and the computer lost the airspeed display on both EFIS's (the main screens that each pilot has). It was a non event. The pilots pulled out their QRH (quick reference handbook) followed the check lists and continued flying for another 3 hours to our mtce base. There was nothing I could do while we were flying except do some research in the manuals. Once on the ground, it was just a matter of resetting the computers to get it back working.
|
Login
Register
FAQ
Search
Calendar
