Re: [thecount] BASE gear from a 182
forward speed will not decrease fast enough for it to matter on a slider down jump.
vertical speed when compared to the ground will increase equally from a low speed airplane and a fixed object.
horizontal speed will dissipate slowly, if the plane is going 60kts when you exit, the horizontal speed will decrease only a few knots in the 3 seconds you freefall before you open a slider down packjob.
basically, if your going 60kts vertical and 55 horizontal [55 after the decay from 60kts horizontal exit speed], you actual airspeed (what matters in a parachute opening) will be about 70-75 kts.