"I was too nonchalant and there is no room for mistakes in this sport," Lange, 44, told The Associated Press on Thursday.
The accident happened Aug. 23, as the experienced BASE jumper leapt off the 1,600-meter- (5,250-foot-) high Bjoerketind peak.
Lange said he was flying down the mountainside at nearly 180 kph (110 mph) when he realized he was too close to the wall.
He deployed his chute and tried to steer away from the wall, but it was too late. The video showed Lange crying out in pain as he bumped into the rock repeatedly while trying to untangle the cords.
The fall came to an abrupt end when he slammed into a tree about 100 meters (330 feet) above the planned landing site.
After overcoming the initial shock, Lange turned to the camera and said: "What a bummer ... Oh well, I'm alive."
He was rescued by a helicopter 45 minutes later.
Lange told AP by telephone he was lucky to be alive but wasn't about to give up the thrill of BASE jumping.
"When I have recovered I will jump again," he said. "It all comes down to better planning. It's a fantastic feeling to fly along a mountainside."
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