What is HFTA
HFTA stands for High-Frequency Terrain Assessment. Some documentation refers to it as High-Frequency Terrain Analysis.
HFTA is a software tool that generates the vertical radiation pattern of horizontally polarized antennas taking into account the profile of the surrounding terrain. The irregularity of local terrain has a profound effect on vertical radiation patterns. Note that HFTA does not compute radiation patterns for vertically polarized antenna radiation.
More details here: https://www.n1fd.org/2021/11/07/hfta-intro/