I still don’t get the black hole illusion. The “picture” should be constant all the way down.
No.
Remembering that the concept is mainly an airliner issue not <7500kg GA. However the illusion is the illusion. The documentation details clearly that an actual constant ‘picture’
approach produces a curved In the vertical plane approach from around 15k to around 2-3k when ordinarily the illusion is broken by light pollution locally or improved references. The initial curve means a steeper descent initially and flattening out after it appears to be low by which time it is lower than should be with an increase in CFIT between that point and the threshold. Or in the case of a very slow responding heavy jet a deep undershoot if it is realised but too much energy is required for the recovery.
GA_Pete is right (as is Noe above) and I can attest that it works that way.
You really have to take note if you are used to landing in an area with (even scattered and sparse) ground lights, and then go on to make a dark night landing in an area without any lights in front of the runway, i.e. if the runway is next to the sea or a forest. PAPI is your friend.
For some (different?) reason I have also noticed many pilots (night flying students) going low in the circuit on downwind or base, much more than in daylight. As if they do not fear hitting obstructions below as long as they cannot see what is there.
