Abstract: An employee was designated as a temporary supervisor during a power plant outage. He went into a vent that exhausted into a smokestack to measure the vent's dimensions. Although he was working approximately 21 meters above the bottom of the smokestack, he was not using any form of fall protection. He went too close to the edge, where the vent joined the smokestack, and fell to the bottom of the smokestack. He died of injuries sustained in the accident. The employer had not identified the vent area as a permit-required confined space or performed a hazard assessment of the work area. Additionally, other employees and supervisors had in the past worked in the vent without using fall arrest equipment.