Skydiving While Taking Time-Dilation Drug

Short story about skydiving while on a time dilation drug

Back in the 1970s when I was still in high school I had a subscription to the Science Fiction Book Club. I’m trying now to locate a short story from that time.

The story tells of a group of people who take a drug (I think it was called Skyy) that would make time seem to pass extremely slowly. They would then skydive together, experiencing it as a gentle weightless floating instead of a free fall.

The story ends in tragedy as they become so used to the slowness that they neglect to deploy their parachutes.

via stackexchange, click below for answer and discussion
https://scifi.stackexchange.com/questions/269126/short-story-about-skydiving-while-on-a-time-dilation-drug