| Unit Name: | Pinetree Line |
| Dates: | 1951–1991 |
| Country: | Canada |
| Branch: | Royal Canadian Air Force United States Air Force |
| Type: | Early-warning radar |
| Role: | Continental Air Defense |
| Command Structure: | North American Aerospace Defense Command |
The Pinetree Line was a series of radar stations located across southern Canada at about the 50th parallel north, along with a number of other stations located on the Atlantic and Pacific coasts. Run by North American Aerospace Defense Command (NORAD) (after its creation), over half were staffed by United States Air Force personnel with the balance operated by the Royal Canadian Air Force. The line was the first coordinated system for early detection of a Soviet bomber attack on North America, but before the early 1950s radar technology quickly became outdated and the line was in full operation only for a short time.
Plans for what would become the Pinetree Line were underway as early as 1946 within the Permanent Joint Board on Defense (PJBD), a Canadian-U.S. organization. However, the costs of running such a system in the post-war era was too high, and instead Canada concentrated on the areas around Ontario and Quebec, while the United States set up stations in the Midwest and along the eastern seaboard.With the successful test of an atomic bomb in the USSR, plans changed considerably. In 1949 Congress agreed to a $161 million construction program in co-operation with the RCAF, for a continuous line of stations across southern Canada. The USAF's Continental Air Command and the RCAF met in October 1950 to start planning, and in January 1951 the PJBD presented Recommendation 51/1 for the Extension of the Continental Radar Defence System. The USAF later requested an additional set of six (potentially) mobile stations to provide low-level coverage. Later, it was learned the original radar systems performed better than expected, hence a number of the mobile sites were never deployed.
The system was eventually deployed as a series of 33 main stations and 6 smaller "gap fillers". The majority of these ran in a line at about the 53rd parallel in the west (to offer coverage of major Canadian cities) and about the 50th parallel in the east. A second line ran up the eastern seaboard from the southern tip of Nova Scotia to the southern tip of Baffin Island. Of these, 22 of the main stations and all of the gap fillers were paid for by the USAF, leaving 11 to the RCAF. However 16 of the main stations were staffed by RCAF personnel. On 1 January 1955, the system was officially handed over to RCAF command, and over time an additional 10 stations were added. The stations on the east coast used the Pole Vault system for communication.
The Pinetree Line had several technical problems that limited its usefulness almost immediately. For one, the system used a simple pulse radar technique, which made it unable to detect targets close to the ground due to radar clutter as well as being trivially easy to jam using the recently-introduced carcinotron tube. Another was that its location near population centres meant it offered only a last minute warning, and as the USSR moved to jet-powered bombers the warning time was reduced. Studies were already underway in 1951 to build a series of Doppler bistatic radar stations somewhat farther north, which would develop into the Mid-Canada Line. By 1957, just over a year after the Mid-Canada Line was operational, a more advanced long-range search radar, mainly in the Canadian north and Alaska were deployed comprising the Distant Early Warning Line.
The Pinetree stations were kept operational during this period, and most underwent modifications as a part of the deployment of the Semi-Automatic Ground Environment (SAGE). SAGE dramatically reduced the workload at the stations, cutting staff requirements by well over half. By the later 1950s some were being mothballed as newer systems came on line to the north. Nevertheless, many of the Pinetree stations were kept operational into the 1980s, particularly on the Atlantic and Pacific coasts.
Initial sort is based on longitude from east to west.
| Site number | Name | Province | Location | Unit | Service | Activated | Deactivated | |
|---|---|---|---|---|---|---|---|---|
| N-22 | Red Cliff Air Station St. Johns Air Station | NL | 642d Aircraft Control and Warning Squadron | USAF | 1953 | 1961 | ||
| N-22B | Elliston Ridge Air Station | NL | 642d Aircraft Control and Warning Squadron | USAF | 1957 | 1961 | ||
| N-25 | CFB Gander | NL | 226 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1953 | 1990 | ||
| N-26B | La Scie Air Station | NL | 921st Aircraft Control and Warning Squadron | USAF | 1957 | 1961 | ||
| N-26 | Saint Anthony Air Station | NL | 921st Aircraft Control and Warning Squadron | USAF | 1953 | 1968 | ||
| N-27C | Fox Harbour Air Station | NL | 922d Aircraft Control and Warning Squadron | USAF | 1957 | 1961 | ||
| N-27B | Spotted Island Air Station | NL | 922d Aircraft Control and Warning Squadron | USAF | 1957 | 1961 | ||
| N-27 | Cartwright Air Station | NL | 922d Aircraft Control and Warning Squadron | USAF | 1953 | 1968 | ||
| N-27A | Cut Throat Island Air Station | NL | 922d Aircraft Control and Warning Squadron | USAF | 1957 | 1961 | ||
| N-23 | Stephenville Air Station | NL | USAF | 1952 | 1971 | |||
| N-28A | Cape Makkovik Air Station | NL | 923d Aircraft Control and Warning Squadron | USAF | 1957 | 1961 | ||
| C-34 | CFS Sydney | NS | 221 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1954 | 1991 | ||
| N-28 | Hopedale Air Station | NL | 923d Aircraft Control and Warning Squadron | USAF | 1953 | 1968 | ||
| C-24 | Goose Air Force Base | NL | Goose Air Defense Sector 21st Air Division 26th Air Division 37th Air Division 59th Fighter-Interceptor Squadron 64th Air Division 95th Strategic Wing 4082d Strategic Wing 4732d Air Defense Group 6603d Air Base Group | USAF | 1953 | 1971 | ||
| N-24 | Melville Air Station | NL | 107th Aircraft Control and Warning Squadron 641st Aircraft Control and Warning Squadron 641 Aircraft Control and Radar Squadron | USAF RCAF | 1953 | 1988 | ||
| N-29 | CFS Saglek | NL | 924th Aircraft Control and Warning Squadron | USAF | 1953 | 1970 | ||
| C-11 | RCAF Beaverbank | NS | 22 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1954 | 1964 | ||
| N-30 | CFS Resolution Island | NT | USAF | 1951 | 1961 | |||
| C-5 | CFS St. Margarets | NB | 21 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1953 | 1988 | ||
| C-102 | CFS Barrington | NS | 672d Aircraft Control and Warning Squadron 23 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1957 | 1990 | ||
| C-33 | CFS Moisie | QC | 211 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1953 | 1988 | ||
| N-31 | Frobisher Bay Air Base | NT | USAF | 1953 | 1961 | |||
| C-6 | RCAF St. Sylvestre | QC | 13 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1955 | 1964 | ||
| C-1 | CFS Mont Apica | QC | 12 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1952 | 1990 | ||
| C-2 | CFS Lac St. Denis | QC | 11 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1952 | 1986 | ||
| C-42 | CFS Chibougamau | QC | 10 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1962 | 1988 | ||
| C-7 | RCAF Parent | QC | 14 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1954 | 1964 | ||
| C-8 | CFS Senneterre | QC | 34 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1953 | 1988 | ||
| C-3 | CFS Foymount | ON | 32 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1952 | 1974 | ||
| C-4 | CFS Edgar | ON | 31 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1953 | 1964 | ||
| C-10 | CFS Ramore | ON | 912th Aircraft Control and Warning Squadron 35 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1953 | 1974 | ||
| C-44 | CFS Moosonee | ON | 15 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1961 | 1975 | ||
| C-9 | CFS Falconbridge | ON | 33 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1952 | 1986 | ||
| C-119 | CFS Lowther | ON | 639th Aircraft Control and Warning Squadron 36 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1957 | 1987 | ||
| C-14 | RCAF Station Pagwa | ON | 913th Aircraft Control and Warning Squadron 37 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1952 | 1966 | ||
| C-15 | CFS Armstrong | ON | 914th Aircraft Control and Warning Squadron 38 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1952 | 1974 | ||
| C-16 | CFS Sioux Lookout | ON | 915th Aircraft Control and Warning Squadron 39 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1953 | 1987 | ||
| C-17 | CFS Beausejour | MB | 916th Aircraft Control and Warning Squadron 48 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1953 | 1988 | ||
| C-49 | CFS Gypsumville | MB | 47 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1962 | 1987 | ||
| C-51 | CFS Yorkton | SK | 46 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1963 | 1986 | ||
| C-52 | CFS Dana | SK | 45 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1964 | 1987 | ||
| C-53 | CFS Alsask | SK | 44 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1953 | 1986 | ||
| C-36 | CFB Cold Lake | AB | 42 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1954 | 1991 | ||
| C-54 | CFS Penhold | AB | 43 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1964 | 1986 | ||
| C-21 | RCAF Saskatoon Mountain CFS Beaverlodge | AB | 919th Aircraft Control and Warning Squadron 57 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1953 | 1988 | ||
| C-153 | CFS Kamloops | BC | 825th Aircraft Control and Warning Squadron 56 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1957 | 1988 | ||
| C-20 | CFS Baldy Hughes | BC | 918th Aircraft Control and Warning Squadron 54 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1953 | 1988 | ||
| C-19 | RCAF Station Puntzi Mountain | BC | 917th Aircraft Control and Warning Squadron 55 Aircraft Control and Warning (later Radar) Squadron | USAF RCAF | 1952 | 1966 | ||
| C-35 | CFB Comox | BC | 51 Aircraft Control and Warning (later Radar) Squadron | RCAF | 1954 | 1958 | ||
| C-36 | RCAF Tofino | BC | 52 Aircraft Control and Warning Squadron | RCAF | 1955 | 1957 | ||
| C-18 | CFS Holberg | BC | 501 Aircraft Control and Warning (later Radar) Squadron 53 Radar Squadron | RCAF | 1954 | 1991 |