Now, I'm not a driver (I hope to be, one day in the distant future
) but I have studied fluid dynamics and I also have an intense interest in the flight controls and laws of all Airbus FBW.
With reference to:
When I said controls were sluggish, I meant the control input didn't give me required increase in the lift.
Do you mean the ROD did not reduce commensurate with what you would expect during the flare, or what you would expect during final approach? Remember, when the aircraft is in Flare mode, at 30' RA the reference attitude is 'washed out' over 8 seconds (Which, I assume means that a nose down trend is introduced) to ensure the PF progressively flares the aircraft. Now, would I be correct in assuming, at this point the control input required to reduce the ROD will be greater than that required during the other flight regimes (Climb/Cruise/Descent/Approach)?
However, if that has been taken into account, and you are very sure you didn't flare late then I would tend to agree with FlightDetent about a low density, high temperature pocket at the threshold. Might seem a real silly question, but are there any watercourses or streams just before the threshold? High localised humidity would decrease the density even further.
Just $0.02.
Tom