I'm not a long range flyier, but I was able to push my P3A out to 4,1km (roughly 2,5 miles). I was using windsurfers, because here in europe it's quite difficult to push the craft out more than 2,5 km (1,5 miles) with stock antennas.
Anyway, I wanted to reach that exact point so I went straight there. I had time to do a little hovering and to explore the area a little, then hitted RTH to come back home. On the way back I started getting nervous because of battery time: therefore I pushed on throttle.
I landed with 25% battery left.
I am sure 3 miles are no problem... but mind the wind.