There are 3 neccessary elements to a good landing ; 1)a stable approach, 2) Flare and cut thrust at the correct height, 3)nobody really knows what the third one is...
The Jacobsen techique relies on being stable (that is: on speed, on slope and with a constant sink rate) and with flare and power reduction initiated when a fixed point on the RWY disappears under the nose. This fulfills criteria 2). On the B747, this is when the first centerline after the piano keys is lost from view. For the B767, it is when the first center marking before the 300m marker disappears. This can be a bit tricky at night! The actual 'skill' part comes from judging at what rate to flare and pull off power. This depends on the conditions of the day (wind, density alt., AUW).I do not know the flare points for GA aircraft, but someone will. A good landing is a SAFE landing. If the touchdown is smooth and halfway down the runway or off-centerline, than it cannot be seen to be safe, can it? A firm touchdown is desirable if the RWY is contaminated with slush or standing water, so as to break the surface tension and not aqua-plane. Thus, a hard landing is not neccessarily a bad one. The Jacobsen technique is very useful for getting the aircraft to the correct touchdown zone on the RWY, but what happens in the last 3 feet is in the lap of the Gods.
