This whole 'don't select until landing assured' discussion gets to me. Let me explain using the ubiquitous 172/152/PA28 with two examples.
Firstly a powered approach (I'll not get into the merits of such an approach, let's just take it as read that people fly these). If an aircraft is set up on a powered approach and at a sensible approach speed the landing is never assured. Dropping flap at 300ft or whatever is only going to forshortened the landing point. Agreed, you could drop the last stage 'over the fence' to drag off a few knots but do we really wish to reconfigure at this point?
Similar scenario but a glide approach. In this scenario the flaps are acting as your engine - controlling angle of descent. If your landing is 'assured' with two stages and you then drop the last stage (drag?) your landing s still assured but not at the same location. Again you will drag the landing point closer to you. This is why most sensible instructors teach that a glide should be aimed towards the far end of the landing area and pilots should adjust this point with the application of flap.
So, in summary, the 'landing assured' phrase needs to be understood in its entirety. Drop flap and do nothing else with the aircraft and you have moved your landing point. Your landing is only assured if you understand this and plan your approach accordingly.
Last edited by Cows getting bigger; 8th Feb 2013 at 06:32.