However, when in normal law, regardless of the pilot's input, the computers will prevent excessive maneuvers and exceedance of the safe envelope in pitch and roll axis.Taken from the flight control section of the 320 FCOM
No Flight Crew Manuals mention all the aerodynamic characteristics of an aircraft. In this instance Airbus elaborated by explaining that the FBW reduced the input due to Longnitudinal Damping (Phugoid). Its a technical way of saying that its easy to overcontrol close to the stall which we all should appreciate especially as the aircraft has a pitch up tendancy close to the stall as highlighted in Safety First which you referenced in another thread.
If you seriously think you can flare an aircraft effectively from 25 odd knots below the manoever speed for the weight and config they were in you are deluded.
Further if you think they would have been better off in Direct Law then you are mistaken. In Direct Law the aircraft is free to stall. At the speed they were at the Stall Warning would have been hammering away for quite some time and there is no AoA gauge and no way of knowing how close to the stall you are. Are you really saying that in Direct Law 25 knots slow on the manoever speed with the stall warning blaring away that the right thing to do is pull.
If it had been a Boeing the stall warning would have been blaring away too, allied to the stick shaker and again no AoA indication so no way to know how close you are to the stall and no feel due to the stick shaker.
Sully did not have to worry about that. He was in an Airbus in normal law, thanks to his actions, that allowed him care free handling and gave him maximum performance. He would emphaticaly have been considerably worse off if he had been in alternate or direct law whatever speed profile he flew.
I am well aware Alpha Max is not Alpha stall. There is a margin for a reason. I am also well aware that there was a gap of 3 AoA to Alpha Max when they impacted due to the FBW mitigating Sully's full aft input. Unlike you I am willing to accept that there was a reason that the FBW mitigated this input. Airbus and the BEA have explained that reason and you still insist you know best. I did not design or certify the aircraft and neither did you. You have no basis in fact for denegrating the design or performance of the aircraft because you do not have the data to base that judgement on. You should take note that the NTSB, who have no axe to grind in Airbus's favour, do not criticise the aircraft or its design.
I am not an aerodynamicist but my practical experience is that it is very very easy to overcontrol close to the stall. It takes finesse and current practise to operate in that regime. Any large aggressive inputs will lead to a stall. Thats why you pull to the buffet then squeeze into it in a Max Rate Turn. At low speed the buffet band is even easier to pull through. So if a pilot makes a full aft stick input in that regime then it is no surprise to me that the aircraft mitigates it. Its exactly what I would have expected.
I've contributed more than enough now so for the time being I'll leave it to others to keep this going if they so desire.
Last edited by Ashling; 6th Oct 2011 at 11:54.