"Another glider was further below him, as is normal when you're in close to the hill.
"He didn't have the distance to clear so hit the other glider."
Mr Eller said the pilot who spun deployed his reserve chute. The other either did not have time to or chose not to.
"The reserve was deployed quickly, and opened perfectly. The two of them settled into the pine trees."
The four paragliders were extracted from the trees by members of the Queenstown's Alpine Cliff Rescue Team and other rescue experts.
Mr Eller estimated the paragliders were about 150m to 200m off the ground when they collided.
"It's not a super uncommon thing for paragliders to end up in trees, so it's a case of extracting them with as ... [few] problems as possible."Mr Eller said the pilots each had more than 15 years' experience paragliding in New Zealand and overseas.
An investigation is under way. Both pilots have been stood down temporarily. The company suspended operations yesterday but will operate today, weather permitting.