There's no major reason to turn off the landing protection or downward sensors, but if you do, then hand catching is easier as it doesn't worry about an 'unsuitable landing site' and just merrily descends into your hand, without any rising or revving of the props.I have yet to find a reason to turn off the sensors or landing protection. I rises slightly as it first detects my hand under it and then settles gently down into my hand. What problem is turning off sensor supposed to fix?
Ian