Hey Folks:
All the answers here are quite correct -- but before I disregarded one or the other I'd make sure what the rules are -- and the rules do differ slightly from country to country. For example the Operating Rules in the US require that, "An airplane approaching to land on a runway served by an instrument landing system (ILS), if the airplane is ILS equipped, must fly that airplane at an altitude at or above the glide slope between the outer marker and the middle marker; and an airplane approaching to land on a runway served by a visual approach slope indicator must maintain an altitude at or above the glide slope until a lower altitude is necessary for a safe landing." Now, admittedly, this is for large airplanes -- but its a pretty good safety practice, and if both are available, its a pretty sure bet that anyone who sticks it in short of the threshold is going to have a lot of questions to answer.
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AirRabbit