The man, in his 30s, was not as badly injured as first thought, when he was struck by the falling ice after investigating the inside of a cooling silo at a chicken processing factory on Dellamarta Road about 2pm.
A WorkSafe spokeswoman said the ice would usually dislodge and collect at the bottom of the silo but it hadn’t, which led to the man peering inside to see what was wrong.
The accident was not discovered until a workmate noticed the man missing.
Fire crews were required to cut a hole in the silo to free the man.
The WorkSafe spokeswoman said this was not because he was trapped, but because they needed to ensure the man was lifted safely in case he had suffered spinal injuries.
He was flown to Royal Perth Hospital via helicopter with severe hypothermia, but was discharged without injury.