The advent of nuclear-powered submarines in the late 1950s let to the RCN assessing this new threat. While noisier than older submarines and thus detectable at longer ranges, nuclear submarines could also reach while submerged, faster than the RCN's new
destroyer escort's top speed of . There were doubts that destroyers could effectively pursue and destroy such fast vessels, even when operating in pairs. During a 25 February 1959 Naval Board meeting, it was decided to counter the threat by operating helicopters from destroyers. The RCN examined the feasibility of operating ASW helicopters from small escorts, adding a temporary helicopter landing platform to the in mid-1956; successful trials were held in October 1956 using a
Sikorsky HO4S-3. A larger temporary platform was fitted on the destroyer escort ; operational trials used an
RCAF Sikorsky S-58, a much larger and heavier aircraft than the HO4S; these successful tests met with approval. The RCN's then current HO4S-3 utility helicopter could not operate safely in inclement weather with a heavy weapons and sensor load, which would be imperative for the ASW role; hence, a more capable aircraft was needed. Initial 1959 studies identified two helicopters that seemed suitable—the Sikorsky S-61 (HSS-2) and the
Kaman K-20 (HU2K)—but neither aircraft had flown at the time, so no choice was made. After further studies concluded that the smaller Kaman would better satisfy RCN requirements, the
Treasury Board approved an initial procurement of 12 HU2K helicopters for $14.5 million in December 1960. These trials confirmed the calculations of RCN staff members; the HU2K was substantially heavier than promised, hampering performance and rendering it incapable of meeting RCN requirements, even using a proposed upgraded engine. The Sea King was ultimately chosen for production on 20 December 1961. The first of 41 helicopters would be delivered in 1963 carrying the designation
CHSS-2 Sea King. Airframe components were made by
Sikorsky in Connecticut but most CHSS-2s were assembled in
Longueuil, Quebec, by United Aircraft of Canada (now
Pratt & Whitney Canada), a subsidiary of Sikorsky's parent company,
United Aircraft. On 27 November 1963, the new landing platform aboard was used for the first operational destroyer landing of a production CHSS-2. Upon the unification of Canada's military in 1968, the CHSS-2 was re-designated
CH-124. In the 1960s, the RCN developed a technique for landing large helicopters on small ship decks, using a 'hauldown' winch (called a "
Beartrap"), earning aircrews the nickname of "Crazy Canucks". The Beartrap allows recovery of the Sea King in virtually any
sea state. In 1968, the RCN,
Royal Canadian Air Force (RCAF) and
Canadian Army unified to form the Canadian Forces; air units were dispersed throughout the new force structure until
Air Command (AIRCOM) was created in 1975. In August 2011, the Canadian Forces reverted to the former structure of the
Royal Canadian Navy,
Canadian Army and
Royal Canadian Air Force. ==Operational service==