I understand all your points made about the VMS - but it still leads me to think about what happened in the lead up to the second event. This isn't the first report by far which had recommended improvements in data acquisition rates for certain aircraft/FDR installations - and this is something in common with other investigative authorities' reports around the world. You're probably familiar with what I think is the best example of the problem concerning low data rates or too few parameters recorded: The "difference in opinion" between the NTSB and Boeing in regard to the investigation of the Colarado Springs accident - and even more demonstrative - comparing how the NTSB REASONABLY interpreted/interpolated the data - and how Boeing did!(in an unashamed attempt to mitigate future potential liability). In this case, any of my criticism is not meant to suggest that I think there was any malice involved or that I think there was a hidden agenda on the boards part.
The data collected by the FDR is certainly not in the same “league” as far as the frequency of data samples taken for things like aircraft
certification is concerned
That is true - but we also know of the additional use of a secondary, non-crash protected/secured system of data acquisition used by some airlines (usually billed as being for better/more cost effective maintenance handling). This system has already provided far superior data than the FDR allowed in the investigation of one particular incident I know of - (uncommanded spoiler movement on a B744).
When problems associated with FDR data have been a feature of so many accident investigations, perhaps the longterm route to solve this problem is a total revamp of the FDR philosophy - and use of current digital recording technology in a total revamp of the system. I think that would be preferable to (what it sometimes seems like to me) continually reading phrases like "Require that within 2 years, all 'brand x' planes be retrofitted with a flight data recorder system capable of...... . Then we would have a dual use system (airline flight
performance/cost/maintenance monitoring and FDR usage) in one system, large sampling rates, a myriad of parameters recorded and a system which actually provides some cost benefit to the operator.
As you suspected, I don't have any issue with simulator fidelity (A previous NTSB recommendation to Boeing about wet/slippery runway sim fidelity and the excursion case accepted). The only relevant issue in my mind concerns the rudder pedal sensitivity used in these tests, which I refer to later. There is one point apparent to me in an incidental way - Airbus, and others, apprehension about the use of the sim for upset training when obviously outside the envelope. While of course I agree with the problems voiced and that training under conditions where the sim is not able or intended to emulate a particular aircraft could lead to potential negative training - when I think that both main OEM's have taken what seems to me the same stance, I wonder how the general aviation body feels about the arguement: for sim training - Upset situations outside the range where sim fidelity cannot be guaranteed versus no sim training at all for those cases (full stall for example)?
To get back to the matter at hand - as far as the simulator tests were concerned - I was deliberately trying to stick to one issue concerning them. That was my point about "most" of the testers using some rudder to recover. One of my reasons for that was that this was the very same simulator set up which was used in the initial, criticised training of AA pilots. Specifically, the deliberate lack of control response when upset scenario is initiated which was reported as a time lag. Also, the second point, which I think limits the strength of arguement comes in
the next section: 1.17.1.2.7 Comparison of Rudder Pedal Responses in the A300-600 Airplane and the American Airlines A310/300 Training Simulator, - this shows that the pedal response in the simulator is considerably less sensitive than that in the aircraft. Far from damaging my point of view - I believe that this is one of it's strong points. Since the board believed, in their opinion of the AA advanced manoevering program, that the pilot was somehow conditioned to inappropriate use of rudder - if for a moment I accept that ascertion to be correct - why did they not apply the same logic to possible conditioning of the pilots expectations of rudder/rudder pedal response from the simulator?
As far the Airbus ground tests were concerned - I believe again that validates my point of view. I agree it's a tough test - but, nevertheless, when they tried the "50% condition" they got reduced aileron - but NOT reduced rudder. When you say "what you believe the test results show", it makes me think that the tests show what the tests show. I'm not trying to be flippant in saying that - but it makes me think that you believe I question the the finding of the board:
"Because of its high sensitivity (that is, light pedal forces and small pedal
displacements), the Airbus A300-600 rudder control system is susceptible to potentially hazardous rudder pedal inputs at higher airspeeds."
I don't disagree - I agree 110%.
The rate of FDR data acquisition is irrelevant unless you believe that the airplane could have been doing something really “screwy” between
FDR captured data points and return to the same state every second or every one-half second.
I'm not saying that - but i'm not quite agreeing either - at least in terms of degree. Of course you're comments concerning momentum of a large transport are true, but I'm not trying to suggest this aircraft was in or heading for an upset - but there's doubt in my mind about pilot perceptions. If I had only read the report and nothing else - I would probably sway more in favour of the second event being nothing unusual. However, I think ALL the evidence given in relation to metrology/wake turbulence effects during the public hearings warrants ,IMO, a bit more balanced/careful consideration than, for example, the casual inclusion of the statement "nothing extraordinary" by the main author of the wake vortex report in the board's final report. Doubt is raised in my mind about the POTENTIAL for something beyond the bounds of the "average" wake encounter in consideration of ALL the evidence which was available to me, and not just the final reports limited (very IMO) summary of the wake vortex data.
None of the pilots used full rudder except when they were asked to – and none of the pilots reversed the control inputs.
But, as I've tried to indicate, they were in a sim which demonstrated, to a reasonable approximation, half the pedal sensitivity that the real aircraft does (section 1.17.1.2.7). Therefore, they had a better chance of getting the amount of rudder they wanted and not ending up in an APC event. On that one statement - I think the benefit of doubt should have been placed with the PF.
But why was he using rudder in the first place?
We already know that most of the board's testers used some rudder when confronted with an upset - and by extension - I believe most line pilots would react in the same way. As for the PF here; Again this comes down to whether he thought he was in, or entering an upset or not. Was he? Almost without doubt/obviously - no. Did he think or perceive he was heading for one? Possibly. Why do I think that? Because, if the second encounter was just the same as the first, and it really was "nothing extraordinary", and he didn't perceive anything unusual - why on earth did he go for rudder in the second - and not the first? When pilots experience wake turbulence every day of the year to some degree or other, when so many consider that it's 'nothing unusual', and if the second event was no different from any other wake encounter - how could the PF in this case of lasted for over 1,800 hours on type?
In my estimation, on the basis of logic, reasonable doubt, the diligent and careful manner in which this particular accident was investigated, and the voluminous amounts of raw and refined data, I think the Board’s report on this one is pretty accurate.
For the most part I agree. As I've tried to say previously - it's only one element of the report that I really disagree with. And even on that one point - its not because I think they didn't demonstrate diligence - but with all the data at their disposal, and that which I have come to know - they and I reach different conclusions as to the role of the PF versus Airbus in the equation.
It's no surprise that this accident has generated disparity among some people - and it's likely it won't be the last. For a good example of that WITHIN a report, check out the report of NZ60's 'erroneous' glideslope capture.
For example: That report states (in part);"The crew were cohesive and had planned carefully for the duty."
while an NTSB submission to the same report states: "This incident approach appears to demonstrate a lack of proper preparation, inappropriate approach procedures, and a breakdown of crew coordination and crew resource management."
AirRabbit, I think at this point we're going to have to agree to disagree, otherwise this is going to go on and on and we'll just end up going around in circles.
