Like all "rules of thumb" my above mentioned statement does not have to be right for every situation and every helicopter.
For the last 15 years, i have been flying 205īs and 212īs in various countries-and the military.
After doing all the checks before landing, the "flying over" as described above gives you the last decision check wether to land or not...
I do not apply to be correct for all kinds of operations-but doing "confined area landings" is my daily business......but i have never flown a piston A/C.....so i donīt know about their performance...
Within Bell helicopters, 10% are more than enough to clear a confined area again-if the conditions stay the same for landing AND for take-off....