Originally Posted by gums
I must point out that the accident started when air data sensors went south. So what do we do when that happens?
Use manual control to set and keep five degrees nose up, wings level attitude. Don't think about ergonomics, stick deflections, active control law or whatever else just use whatever control input is necessary to maintain 5° ANU. Set climb power. Ask your assisting pilot to dig out QRH and find attitude and power setting for weight, altitude and phase of the flight. Oh wait... that's exactly what "Unreliable airspeed" drill memory items tell you to do.
Trick is to have each and every airline pilot remember them and perform them flawlessly when his body clock says its 4AM, when he's jet-lagged, when he hasn't handflown the plane above FL100 for ages (if ever), when he does less than half a dozen manual landings per month, when he has never experienced control laws degradation and protection loss in real life and only seldom in simulator, when his knowledge of the principles of flight is lacking as he was only made to memorize the multiple choice answers to pass ATPL exams, etc... Whoever patents practical solution to this problem will quickly become millionaire.
Originally Posted by gums
He was too early for the AA regional ATR accident when the A/P was feeding in control deflection due to ice build up. When all went to hell in a handbasket, Sad sad, and there was also some distractions in the cockpit for ten or fifteen minutes before A/P disconnect.
Simmons Airlines crash at Roselawn is a fantastic example of damage that zealous investigation can do to the efforts of increasing the flight safety. NTSB was after ATR and DGAC, BEA was set to defend them at all costs so went after pilots and in-between, many aerospace professionals who would benefit from understanding what actually happened at Roselawn were hopelessly confused.
A/P wasn't feeding any control deflection as ice was accumulating. Ice accumulation was light to moderate and did not affect the overall aerodynamics or performance of the aeroplane in any significant way. It was ridges of ice that formed on outboard parts of the wings, behind the de-icing boots that doomed the flight. It was result of flying with low speed and low AoA (feat made possible by extending the flaps in holding pattern to reduce pitch and improve passenger comfort) through area of supercooled large droplets - a largely unknown meteorological phenomenon at the time. These ridges destroyed ailerons' aerodynamic balance and caused hinge moment reversal at pretty low AoA - instead of centering under dynamic pressure, ailerons snapped to full right wing down position and that's what tripped the autopilot, surprising the crew and leaving them with roll control that needed very heavy force to move away from extreme position. Control was regained once, sadly lost again and when it was regained second time, there was no room to recover. Stabilizer and outboard portions of wings separated at 375 kts and 4G (IIRC Vmo on 72-200 was 230 kt). What got just cursory mention in NTSB report is that F/O tried to extend the flaps again as the aeroplane rolled, but as the speed was above limiting for flaps 15, flap extension was inhibited. Quite a reasonable feature that prevents blowing the flaps away now prevented recovery. Take note those of you seeking solution in more technology.
NTSB claimed that ATR and DGAC were aware of possible roll anomalies with ATR, yet they designed, certified and produced aeroplane as it was. Of course they knew about aileron hinge moment reversal, wind tunnel tests found it at 26° AoA, so far outside flight envelope that they never mentioned it to pilots. Bear in mind that ATR has very malign natural stall tendencies, it needs to be fitted with stickpusher to get certified and if you ever actually stall her, only luck can prevent your last flight from becoming hot topic on PPRuNe. During icing testing, no untoward effects of ice on controls were observed as there wasn't the method, and still there is none, for icing tankers to create SLDs so I really don't think there was conspiracy on ATRs and DGAC part to hide the dangerous side of ATR from her operators.
However, BEA played dirty. It tried to shift the focus from aeroplane to pilots and accused the crew of virtual dereliction of duty in critical phase of flight. That's where "distraction in cockpit" and "severe icing" myths mainly came from. Yes, there was cockpit banter but it was not out of ordinary and did not distract the crew from flying. The crew noticed ice accumulation and turned on de-icers. Their decision to hold with flaps was slightly unusual but not unreasonable as no one at the time knew that it could turn lethal. Our unlucky colleagues were test pilots without them ever realizing they were so. As Peter Garrison brilliantly summed up:
Airplanes were picking up the ice since there were first airplanes. They get heavier and draggier, they propellers vibrate and engines overheat but pilots don't expected their controls to slam to stops without warning.
All you BEA bashers, please take no comfort or support to your fancy theories from my opinion on BEA's handling of Roselawn crash. IMHO, BEA is doing terrific job with AF447 investigation and there's quite easy to see whether report gets excessively biased: just check factual information against analysis, conclusions and recommendations to see if there's large discrepancy, which is good indication of foul play. One just needs a bit of aeronautical salt to do it.