Sightless Parachuting

A blind man was describing his favorite sport: parachuting.... When the reporter asked how he was able to accomplished such a great feat, he said he couldn't do it without the assistance of others: "I am placed by the open doorway," said the blind man, "and told when to jump. I just put my hand on the release ring and out I go" "But how do you know when you are going to land?" asked the reporter. "I have acquired a very keen sense of smell and I can easily detect the trees and grass when I am 300 feet from the ground" he answered. The reporter then asked: "But how do you know when to lift your legs for the final arrival on the ground?"
The blind man quickly answered "Oh, the dog's leash goes slack."