A man is in hospital recovering from non-life threatening injuries, the day after he leapt off the roof of a 40-storey downtown Calgary building.

Police say a 41-year-old man wearing a parachute jumped from the roof of the TD Canada Trust building shortly after 11 p.m. Thursday night.

Partway through his descent, at the building's 24th floor to be precise, he smashed into a window.

"He was then out of control coming down to the ground and landed on the atrium on the fifth floor smashing out the window on the fifth floor," police Sgt. Mike Lomore told CTV's Calgary affiliate, CFCN News.

"All the glass on the 24th floor came down and broke a lot of windows in the atrium as well."

The man's girlfriend, who was waiting on the ground to assist in a planned getaway, instead called emergency services.

A helicopter was called in to first locate and then rescue the man from the top of a pedestrian walkway.

One paramedic told CFCN that the man was alert when they arrived.

"He was conscious, he was talking and he was obviously in a lot of pain," the paramedic said. "One of the things he did relay to the paramedics was there was obviously a miscalculation."

He was taken to Foothill Hospital for treatment of pelvic and back injuries.

Investigators believe the man was trying to BASE jump from the building when he was pushed back towards it by a wind current.

An acronym for buildings, antennae, spans and earth, BASE jumping is a so-called extreme sport that has seen people leap from some of the world's tallest landmarks.

There was no word how the man managed to gain access to the roof of the Calgary tower.

Charges are pending.