Visually concentrate more on the near-field view and periferal vision; you cannot see the far end of the runway in reduced visibility.
There is anecdotal evidence that the 'human' control-law for flaring relates height against height-rate; dependant on aircraft type. This can be seen in the difference between a 3 deg approach and a steeper one - commencing flare at a higher altitude due to the higher vertical speed.
A similar effect might be encountered with sloping runways, but experience suggests that the variation in the quality of landing due to slope is within the variation of normal landings due to a range of airspeeds / ground speeds (changes ht rate and time of flare), and mass - the feel of the aircraft - pitch rate and time.
The basis of control depends on visual assessment of height - akin to 3D triangulation from the close-in visual scene, thence judgement of height rate.
Note the value of height call outs in larger aircraft during the flare.
This judgement, and the pitch rate and time relationship comes with experience on type. Try to capture the overall picture of what is seen, the control input, and progress, for a self debrief, ( experience is like having a large book of pictures )
.
Last edited by safetypee; 25th Jan 2024 at 10:35.
Reason: Clarity, typo