The CN Tower commemorated its 50th anniversary this week, marking five decades since its exterior was completed in April 1975 and the observation decks opened to the public in June 1976.
One of the most dramatic moments in the tower’s construction occurred when engineers lifted the final 102‑metre steel broadcasting antenna into place, a task that required a novel solution beyond conventional crane work.
Initially, the project team explored the use of a giant balloon to hoist the antenna mast, studying similar balloon operations on the West Coast. The concept was abandoned after engineers concluded that balloon technology was insufficiently mature, prompting the decision to employ a helicopter instead.
A 10‑ton Sikorsky S‑64E sky crane, nicknamed “Olga,” was flown from the United States at a cost of US$230,000. The helicopter’s involvement shaved an estimated five months from the construction schedule.
The operation began by attaching a harness to the crane’s 80‑foot front boom and extracting pins that secured the boom to the aircraft. When the south‑side pins were removed, the boom lurched due to an unbalanced harness, and the north‑side pins were found twisted and jammed.
To free the jammed pins, workers positioned torches and carefully burned them out, a slow but effective method that allowed the boom to swing loose. Once released, the sky crane gently lowered the antenna boom to the ground.
Conducting such precise lifts at the tower’s height presented unique challenges, including limited fuel—only about 50 minutes for an operation expected to last ten minutes—and unpredictable wind patterns created by the tower’s own structure.
Despite these obstacles, the successful installation of the antenna solidified the tower’s status as an engineering landmark and remains a celebrated episode in the city’s architectural history.
