Originally Posted by Dave Spart
If the speed is low, a hard landing is more likely because of a lack of elevator authority when the pilot flares by pulling back on the control column to cushion the touchdown.
I am not so sure on the 'lack of elevator authority', I thought it was more to do with the lack of lift being generated by the wings to support the weight (very simply put as the vector diagram would have a small component of lift coming from the engine thrust with the nose up). The elevator is still effective, it's just that you are going too slow and in order to balance it out; at a very slow speed you would need too much elevator (leading to the tail being too low and tailstrike) and lots more thrust.....I'm sure one of our techie friends will explain in Mr Boeing's language for those really interested.
PP