Hi guys
A few comments if I may:
Clearly the business of certification in general (not any specific test) is about getting good data about how the aircraft flies. The best (ie repeatable) data comes from measurements taken in as near steady state circumstances as possible. When steady state is not possible then one lets the least important term change – a good example being if you want to plot angle of attack against g at a particular speed. In this case inevitably when tightening the turn you will eventually not have enough thrust available to hold speed and height so you descend as required to hold the speed – in this case letting height change.
When it comes to this topic – involving stalling in some particular configuration of flaps gear etc - then just selecting idle power and holding height (flying club style) the aircraft will decelerate quite rapidly (speed not constant, AoA not constant) and so when the thing eventually ‘stalls’ you will likely overshoot the actual stall AoA and finish up at an even lower speed, an even higher AoA and really in some quite unknown post stall condition where nothing is steady. This can be unpleasant for the inexperienced student and could even become dangerous should a spin result. But the main thing is such an exercise is useless when it comes to getting good (ie repeatable) flight test data.
Hence the slow 1 kt per sec approach to the speed reduction so that the aircraft is in quasi steady state so far as the aerodynamics are concerned with nothing changing rapidly. Of course you have to accept a loss of height to do this. However such a change of height does not really affect the plot you are able to get of IAS vs AoA which is the object of the exercise. Even more importantly (especially with a new type) you are only creeping the AoA up and so if some aerodynamic event occurs (buffet, wing drop, aileron snatch, tendency for the nose to pitch up etc) then you only have to relax the back pressure a tad and you are instantly back to where you were before the event. All nice and safe and leaves you able to record the data as appropriate (well in my day you had to write it down – although today everything will be recorded for you of course).
So far as the 1 kt per sec goes I was always taught that this was a maximum acceptable rate of reduction and the slower the better. So if you took 5 sec to knock another 1 kt off all to the good.
Off topic and speaking personally if ab initio flying instructors taught stalling this way then the student would not get alarmed and actually perhaps enjoy flying slowly rather than being frightened whenever the ASI needle starts to get lower than usual.