Ok,
ui_typerole=Rotorcraft in aircraft.cfg
makes the simboject spawnable on helipads
But there is glitch on the worldmap: clicking on the H (heliport) as departure, using proper Asobo helis, snaps the start location to first helipad for that heliport
Using old non-really-proper-but-still-nice "helicopters like flying stuff" corrected with ui_typerole, clicking in the H in worldmap as departure, the generic "RUNWAY" remains selected, and clicking in fly now the spawn location is gonna be the "H" positioning itself:the center of the airport
Sooo... What .cfg or .flt parameter is the worldmap looking for for correct spawn?
Of course cloning ALL the .flt and .cfg from a proper Asobo helicopter to other helicopter-like simobject fix the issue, so it must be another parameter (not inside the aircraft.cfg)