Originally Posted by
Mad (Flt) Scientist
For those advocating use of AOA for approach instead of airspeed. If the aircraft weight is correctly known, they amount to the same thing. Consider, though, what happens if the weight is wrong.
Assume the aircraft is 5% heavier than calculated (a pretty gross error, but its just a number...)
For an aircraft flying airspeed, it will be flying at a higher AOA than it should (effectively flying at 1.20 Vsr instead of 1.23Vsr) and it will also have 5% more energy/moment to bring to rest - say 5% more landing roll required (though in fact the brakes will work better, so it'll be less in practice)
If instead the aircraft flies AoA, it'll be at the 'correct' 1.23vsr, and consequently 2.5% faster than the book says for the weight. Therefore it'll now have 10% more enegry/moment to bring to a halt.
Flying AoA protects more in terms of stall speed margins, but puts all the error into the landing distance, unless you recalculate based on the actual speed flown (which would seem a bit of an imposition)
I guess it depends on where your priorities lie. Given worst-case scenarios, would you rather stall on final, or overrun the runway? I'm pretty certain of my answer.
Originally Posted by
Mad (Flt) Scientist
Perhaps Cessna are denying you the gauge by default because they WANT you to use the data from the manual, perhaps because it isn't just a simple function of AoA.....
Perhaps. But perhaps not. But pray tell, if it's not a simple function of AoA, then just what exactly
else do you suppose is figured into a climb calculation when you're already at max power?! Last time I checked, there's only 2 things can determine climb performance: pitch and power.