The Pinetree Line was a series of radar

Radar

Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 stations located across the northern United States and southern Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 at about the 50th parallel north

50th parallel north

The 50th parallel north is a circle of latitude that is 50 degrees north of the Earth's equatorial plane. It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean....

, along with a number of other stations located on the Atlantic and Pacific coasts. Run by NORAD

North American Aerospace Defense Command

North American Aerospace Defense Command is a joint organization of Canada and the United States that provides aerospace warning, air sovereignty, and defense for the two countries. Headquarters NORAD is located at Peterson AFB, Colorado Springs, Colorado...

 (after its creation), over half were manned by United States Air Force

United States Air Force

The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...

 personnel with the balance operated by the Royal Canadian Air Force

Royal Canadian Air Force

The history of the Royal Canadian Air Force begins in 1920, when the air force was created as the Canadian Air Force . In 1924 the CAF was renamed the Royal Canadian Air Force and granted royal sanction by King George V. The RCAF existed as an independent service until 1968...

. The line was the first coordinated system for early detection of a Soviet

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 bomber attack on North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, but the early 1950s radar technology quickly became outdated and the line was in full operation only for a short time.

History

Plans for what would become the Pinetree Line were underway as early as 1946 within the Permanent Joint Board on Defence (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

Ontario

Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

 and Quebec

Quebec

Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....

, 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

Soviet atomic bomb project

The Soviet project to develop an atomic bomb , was a clandestine research and development program began during and post-World War II, in the wake of the Soviet Union's discovery of the United States' nuclear project...

, 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. It was later learned that the original radar systems performed better than expected, and 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

53rd parallel north

The 53rd parallel north is a circle of latitude that is 53 degrees north of the Earth's equatorial plane. It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean....

 in the west (to offer coverage of major Canadian cities) and about the 50th parallel

50th parallel north

The 50th parallel north is a circle of latitude that is 50 degrees north of the Earth's equatorial plane. It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean....

 in the east. A second line ran up the eastern seaboard from the southern tip of Nova Scotia

Nova Scotia

Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...

 to the southern tip of Baffin Island

Baffin Island

Baffin Island in the Canadian territory of Nunavut is the largest island in the Canadian Arctic Archipelago, the largest island in Canada and the fifth largest island in the world. Its area is and its population is about 11,000...

. 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 manned by RCAF personnel. On January 1, 1955, the system was officially handed over to RCAF command, and over time an additional 10 stations were added.

The Pinetree Line had several technical problems that limited its usefulness almost immediately. For one, the system used a "classic" pulsed mode radar, which made it unable to detect targets close to the ground due to "clutter". Another was that its location near population centres meant it offered only a "last minute" warning, and as the USSR moved to jet

Jet engine

A jet engine is a reaction engine that discharges a fast moving jet to generate thrust by jet propulsion and in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets...

-powered bombers the warning time was falling. Studies were already underway in 1951 to build a much smaller series of much more capable Doppler radar

Doppler radar

A Doppler radar is a specialized radar that makes use of the Doppler effect to produce velocity data about objects at a distance. It does this by beaming a microwave signal towards a desired target and listening for its reflection, then analyzing how the frequency of the returned signal has been...

 stations somewhat further north, which would develop into the Mid-Canada Line

Mid-Canada Line

The Mid-Canada Line, also known as the McGill Fence, was a line of radar stations across the "middle" of Canada to provide early warning of a Soviet bomber attack on North America. It was built to supplement the less-advanced Pinetree Line, which was located further south...

, and just over a year after MCL, a more advanced system in the extreme north was built which would be known as the DEW Line.

The Pinetree stations were kept operational during this period, and most underwent modifications as a part of the deployment of SAGE

Semi Automatic Ground Environment

The Semi-Automatic Ground Environment was an automated control system for tracking and intercepting enemy bomber aircraft used by NORAD from the late 1950s into the 1980s...

. 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.

Radar stations

Site Number	Name	Province	Location	Unit	Service	Activated	Inactivated
C-53	CFS Alsask	SK	51°22′00"N 109°58′59"W	44 Aircraft Control and Warning (later Radar) Squadron	CAF	1953	1986
C-15	CFS Armstrong CFS Armstrong Canadian Forces Station Armstrong is a closed General Surveillance Radar station. It is located east of Armstrong, Ontario. It was closed in 1974.It was operated as part of the Pinetree Line network controlled by NORAD.-Origins:...	ON	50°18′19"N 089°00′49"W	914th Aircraft Control and Warning Squadron 914th Aircraft Control and Warning Squadron The 914th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Duluth Air Defense Sector, Air Defense Command, stationed at Armstrong Air Station, Ontario, Canada... 38 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1952	1974
C-20	CFS Baldy Hughes CFS Baldy Hughes Canadian Forces Station Baldy Hughes is a closed General Surveillance Radar station. It is located south-southwest of Prince George, British Columbia...	BC	53°37′06"N 122°56′08"W	918th Aircraft Control and Warning Squadron 918th Aircraft Control and Warning Squadron The 918th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Seattle Air Defense Sector, Air Defense Command, stationed at Baldy Hughes Air Station, British Columbia, Canada... 54 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1953	1988
C-102	CFS Barrington CFS Barrington Canadian Forces Station Barrington, also referred to as CFS Barrington, was a Canadian Forces Station located in the unincorporated community of Baccaro, Nova Scotia at Baccaro Point near the southwestern-most point of the province.-History:...	NS	43°27′06"N 065°28′17"W}	672d Aircraft Control and Warning Squadron 672d Aircraft Control and Warning Squadron The 672d Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Boston Air Defense Sector, Air Defense Command, stationed at Barrington Air Force Station, Nova Scotia... 23 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1957	1990
C-17	CFS Beausejour CFS Beausejour Canadian Forces Station Beausejour is a closed General Surveillance Radar station. It is located east-northeast of Winnipeg, Manitoba...	MB	50°08′53"N 096°13′24"W	916th Aircraft Control and Warning Squadron 916th Aircraft Control and Warning Squadron The 916th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Grand Forks Air Defense Sector, Air Defense Command, stationed at Beausejour Air Station, Manitoba, Canada... 48 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1953	1988
C-11	RCAF Beaverbank	NS	44°55′49"N 063°43′33"W	22 Aircraft Control and Warning (later Radar) Squadron	CAF	1954	1964
C-21	RCAF Saskatoon Mountain CFS Beaverlodge CFS Beaverlodge Canadian Forces Station Beaverlodge is a closed General Surveillance Radar station. It is located east-northeast of Beaverlodge, Alberta...	AB	55°13′51"N 119°18′19"W	919th Aircraft Control and Warning Squadron 919th Aircraft Control and Warning Squadron The 919th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Spokane Air Defense Sector, Air Defense Command, stationed at Saskatoon Mountain Air Station, Alberta, Canada... 57 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1953	1988
N-27	Cartwright AS	NL	53°43′28"N 056°57′51"W	922d Aircraft Control and Warning Squadron	USAF	1953	1968
C-42	CFS Chibougamau	QC	49°56′53"N 074°20′03"W	10 Aircraft Control and Warning (later Radar) Squadron	CAF	1962	1988
C-36	CFS Cold Lake	AB	54°26′05"N 110°10′47"W	42 Aircraft Control and Warning (later Radar) Squadron	CAF	1954	1991
C-35	CFB Comox CFB Comox Canadian Forces Base Comox , commonly referred to as CFB Comox, is a Canadian Forces Base located north northeast of Comox, British Columbia. It is primarily operated as an air force base by the Royal Canadian Air Force and is one of two bases in the country using the CP-140 Aurora...	BC	49°42′39"N 124°53′12"W	51 Aircraft Control and Warning (later Radar) Squadron	CAF	1954	1958
C-52	CFS Dana	SK	52°16′42"N 105°46′09"W	45 Aircraft Control and Warning (later Radar) Squadron	CAF	1964	1987
C-4	CFS Edgar	ON	44°31′47"N 079°39′33"W	31 Aircraft Control and Warning (later Radar) Squadron	CAF	1953	1964
C-9	CFS Falconbridge	ON	46°37′34"N 080°50′36"W	33 Aircraft Control and Warning (later Radar) Squadron	CAF	1952	1986
C-3	CFS Foymount	ON	45°26′01"N 077°18′08"W	32 Aircraft Control and Warning (later Radar) Squadron	CAF	1952	1974
N-31	Frobisher Bay AB	NU	63°45′21"N 068°32′23"W	926th Aircraft Control and Warning Squadron 926th Aircraft Control and Warning Squadron The 926th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Goose Air Defense Sector, Air Defense Command, stationed at Frobisher Bay Air Base, Northwest Territories, Canada...	USAF	1953	1961
N-25	CFB Gander CFB Gander Canadian Forces Base Gander , is a Canadian Forces Base located in Gander, Newfoundland and Labrador. It is operated as an air force base by the Royal Canadian Air Force and is home to air/marine search and rescue operations that cover a vast swath of the western North Atlantic and southern Arctic...	NL	48°56′13"N 054°34′05"W	226 Aircraft Control and Warning (later Radar) Squadron	CAF	1953	1990
N-24 C-24	Melville AS CFB Goose Bay CFB Goose Bay Canadian Forces Base Goose Bay , is a Canadian Forces Base located in the town of Happy Valley-Goose Bay, Newfoundland and Labrador....	NL	53°17′45"N 060°32′24"W	107th Aircraft Control and Warning Squadron 641st Aircraft Control and Warning Squadron 641st Aircraft Control and Warning Squadron The 641st Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the 21st Air Division , Tactical Air Command, stationed at Melville Air Station, Newfoundland and Labrador, Canada... 641 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1953	1988
C-49	CFS Gypsumville	MB	51°39′51"N 098°44′31"W	47 Aircraft Control and Warning (later Radar) Squadron	CAF	1962	1987
C-18	CFS Holberg	BC	50°38′25"N 128°07′48"W	501 Aircraft Control and Warning (later Radar) Squadron 53 Radar Squadron	CAF	1954	1991
N-28	Hopedale AS	NL	55°27′59"N 060°13′47"W}	923d Aircraft Control and Warning Squadron	USAF	1953	1968
C-153	CFS Kamloops CFS Kamloops Canadian Forces Station Kamloops is a closed General Surveillance Radar station. It is located northeast of Kamloops, British Columbia...	BC	50°48′08"N 120°07′36"W	825th Aircraft Control and Warning Squadron 825th Aircraft Control and Warning Squadron The 825th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Spokane Air Defense Sector, Air Defense Command, stationed at Kamloops Air Station, British Columbia, Canada... 56 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1957	1988
C-2	CFS Lac St. Denis CFS Lac St. Denis Canadian Forces Station Lac St. Denis is a former Canadian Forces Station that was located by Lac St. Denis, 60 miles north of Montreal in the Laurentian Mountains.-Construction:...	QC	45°56′15"N 074°18′41"W	11 Aircraft Control and Warning (later Radar) Squadron	CAF	1952	1986
C-119	CFS Lowther CFS Lowther Canadian Forces Station Lowther is a closed General Surveillance Radar station. It is located east-southeast of Mattice-Val Côté, Ontario...	ON	49°33′21"N 082°59′31"W	639th Aircraft Control and Warning Squadron 639th Aircraft Control and Warning Squadron The 639th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Sault Sainte Marie Air Defense Sector, Air Defense Command, stationed at Lowther Air Station, Ontario, Canada... 36 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1957	1987
C-33	CFS Moisie	QC	50°11′39"N 066°05′16"W	211 Aircraft Control and Warning (later Radar) Squadron	CAF	1953	1988
C-1	CFS Mont Apica	QC	47°58′41"N 071°25′51"W	12 Aircraft Control and Warning (later Radar) Squadron	CAF	1952	1990
C-44	CFS Moosonee	ON	51°17′10"N 080°37′23"W	51 Aircraft Control and Warning (later Radar) Squadron	CAF	1961	1975
C-14	RCAF Station Pagwa RCAF Station Pagwa Royal Canadian Air Force Station Pagwa is a General Surveillance Radar station that was closed in 1966. It was located at the unincorporated place and railway point of Pagwa in geographic Bicknell Township, Unorganized North Cochrane District in northeastern Ontario, Canada.It was operated as...	ON	50°01′04"N 085°15′06"W	913th Aircraft Control and Warning Squadron 913th Aircraft Control and Warning Squadron The 913th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Sault Sainte Marie Air Defense Sector, Air Defense Command, stationed at Pagwa Air Station, Ontario, Canada... 37 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1952	1966
C-7	RCAF Parent	QC	47°53′15"N 074°40′09"W	14 Aircraft Control and Warning (later Radar) Squadron	CAF	1954	1964
C-54	CFS Penhold	AB	52°11′16"N 113°34′41"W	43 Aircraft Control and Warning (later Radar) Squadron	CAF	1964	1986
C-19	RCAF Station Puntzi Mountain RCAF Station Puntzi Mountain RCAF Station Puntzi Mountain is a closed General Surveillance Radar station. It is located north-northwest of Vancouver, British Columbia...	BC	52°09′41"N 124°12′22"W	917th Aircraft Control and Warning Squadron 917th Aircraft Control and Warning Squadron The 917th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Seattle Air Defense Sector, Air Defense Command, stationed at Puntzi Mountain Air Force Station, British Columbia... 55 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1952	1966
C-10	CFS Ramore CFS Ramore Canadian Forces Station Ramore is a closed General Surveillance Radar station. It is located east of Ramore, Ontario. It was closed in 1974.It was operated as part of the Pinetree Line network controlled by NORAD.-History:...	ON	48°25′37"N 080°14′30"W	912th Aircraft Control and Warning Squadron 912th Aircraft Control and Warning Squadron The 912th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Sault Sainte Marie Air Defense Sector, Air Defense Command, stationed at Ramore Air Station, Ontario, Canada... 35 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1953	1974
N-30	CFS Resolution Island CFS Resolution Island CFS Resolution Island is a short-range radar site. It is located north-northwest of CFB Goose Bay, Labrador and Newfoundland. It is part of the North Warning System...	NU	61°35′47"N 064°38′18"W	920th Aircraft Control and Warning Squadron 920th Aircraft Control and Warning Squadron The 920th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Goose Air Defense Sector, Air Defense Command, stationed at Resolution Island Air Station, Northern Territories, Canada...	USAF	1951	1961
N-29	Saglek AS	NL	58°29′19"N 062°35′08"W	924th Aircraft Control and Warning Squadron	USAF	1953	1970
C-8	CFS Senneterre	QC	48°21′41"N 077°13′21"W	34 Aircraft Control and Warning (later Radar) Squadron	CAF	1953	1988
C-16	CFS Sioux Lookout CFS Sioux Lookout Canadian Forces Station Sioux Lookout is a closed General Surveillance Radar station. It is located west of Sioux Lookout, Ontario...	ON	50°04′59"N 092°00′08"W	915th Aircraft Control and Warning Squadron 915th Aircraft Control and Warning Squadron The 915th Aircraft Control and Warning Squadron is an inactive United States Air Force unit. It was last assigned to the Duluth Air Defense Sector, Air Defense Command, stationed at Sioux Lookout Air Station, Ontario, Canada... 39 Aircraft Control and Warning (later Radar) Squadron	USAF CAF	1953	1987
N-26	Saint Anthony AS	NL	51°20′57"N 055°36′39"W	921st Aircraft Control and Warning Squadron	USAF	1953	1968
N-22	Red Cliff AS St. Johns AS	NL	47°38′20"N 052°40′02"W	642d Aircraft Control and Warning Squadron	USAF	1953	1961
C-5	CFS St. Margarets RCAF Station St. Margarets RCAF Station St. Margarets is a former Royal Canadian Air Force station and later a Canadian Forces detachment located in the community of St. Margarets, New Brunswick....	NB	46°54′31"N 065°12′31"W	21 Aircraft Control and Warning (later Radar) Squadron	CAF	1953	1988
C-6	RCAF St. Sylvestre	QC	46°22′04"N 071°13′51"W	206 Aircraft Control and Warning (later Radar) Squadron	CAF	1955	1964
N-23	Stephenville AS	NL	48°35′21"N 058°39′51"W	105th Aircraft Control and Warning Squadron 640th Aircraft Control and Warning Squadron	USAF	1952	1971
C-34	CFS Sydney	NS	46°10′03"N 060°09′52"W	221 Aircraft Control and Warning (later Radar) Squadron	CAF	1954	1991
C-36	RCAF Tofino RCAF Station Tofino When Japan entered the Second World War the emphasis shifted from Europe to the Pacific Ocean. On Vancouver Island we had a sea plane base at Patricia Bay. The RCAF, due to the threat of Japanese incendiary balloons established an airfield at Tofino BC. First access was by logging road and water...	BC	49°04′55"N 125°46′51"W	52 Aircraft Control and Warning Squadron	CAF	1955	1957
C-51	CFS Yorkton	SK	51°17′41"N 102°36′21"W	46 Aircraft Control and Warning (later Radar) Squadron	CAF	1963	1986

See also

• List of Royal Canadian Air Force stations
• List of USAF Aerospace Defense Command General Surveillance Radar Stations

External links