Most of the manufacturers do not give any real range numbers. I'm sure it is a product liability issue since lots of things can impact the range and giving a number could be a risk.

Some of the Futaba receivers have this in the tech notes:
"Perfect for Park or Slow Flyers. Range of approximately 650 feet (200m)"

If you keep the AR6100 at least that close you are probably fairly safe. With a model airplane you can be beyond 650 feet very quickly.