The steps for a safe landing:
a) A stabilized approach, targeting a glideslope of -3 degrees and an indicated airspeed of VREF, should be maintained for a sufficient time prior to reaching a height of 50 feet above the landing surface. During this time, there should be no appreciable change in the power or thrust setting, pitch attitude, or rate of descent. The glideslope should not be steeper than -3 degrees.
b) Below 50 feet, there should be no nose depression by use of the longitudinal control and no change in configuration that requires action by the pilot, except for reduction in power or thrust.
c) The average touchdown rate of sink at TD shall not exceed 3 feet per second and the maximum rate of sink at TD not to exceed 6 ft/s.
So we are looking at a VS of around 180 FPM and everything over 360 FPM is already a hard landing. The 747-400 FCTM also states:
- Do not allow the airplane to float: Fly the airplane onto (not into) the runway
- Do not extend the flare by increasing pitch attitude in an attempt to achieve a perfectly smooth touchdown.
- Landing with extremely low sink rates is more likely to experience a landing gear shimmy event than a firmer landing because the torsion links remain in an extended vertical position where the damper has less mechanical advantage for longer periods of time
Here at 3:17 min you can see what a shimmy event is: