The Story of Plant #1 at Downsview

By David Wencer, originally published November 10, 2011

De Havilland hangar spans our aviation history

Beaver’s First Flight (Canadian Air & Space Museum)

Downsview’s aviation history traces its origins to De Lesseps Field near Jane Street and Trethewey Drive where, in 1928, de Havilland Canada had its first facility. De Havilland was, up until World War II, a relatively small aircraft company in Canada, initially established by the British de Havilland Aircraft Company to construct Moth aircraft out of parts manufactured in England. At the time of de Havilland Canada’s founding, the Moth was standard equipment for most flying clubs.

Factory before the war (Canadian Air & Space Museum)

In October of 1928, after only a few months at Mount Dennis, a new, more spacious site for de Havilland was chosen, that being Downsview. Downsview was flat, rural farmland, convenient to Toronto yet relatively isolated from major development. The acquisition of land at Downsview was described in the December 20, 1928 Toronto Star as “not only [an] important step in the history of aviation but [a] further indication of Toronto’s industrial progress.” Downsview provided ample open space for both test flying and future site expansion; access to the Canadian National Railway along the original western boundary made it easy for the company to receive and ship parts. De Havilland moved to their new location in the first week of September, 1929, having erected new facilities out of steel while also bringing with them a portable wooden hangar from De Lesseps Field.

Administration Offices (Canadian Air & Space Museum)

During the 1930s, de Havilland built, repaired and maintained small aircraft. It should be pointed out that they were not the only aircraft industry in North York at this time. The Downsview episode of Rogers TV’s Structures notes that Canadian Airways, the Toronto Flying Club, and the civilian airfield Barker Field were all in the Downsview area before the war.

In 1937, de Havilland was given a contract by the Department of National Defence (DND) to build 25 Tiger Moths. This contract prompted the first significant wave of expansion on the site, with the original building, sometimes known as Plant #1, receiving the first of four additions; other buildings were also erected on the Downsview site at this time.

The Tiger Moth (Canadian Forces photo)

The next major assembly line order de Havilland received came in 1940 and was considerable: 404 Tiger Moths. This prompted de Havilland to further expand, building a second major plant on their site later that year, along with additional hangars and paved runways, which displaced Dufferin Street. According to a 1990 report on the site prepared by Canada’s Federal Heritage Buildings Review Office (FHBRO), the Downsview plant produced 1,384 Tiger Moths between 1939 and 1945. Due to its relative simplicity to construct, fly, and maintain, the Tiger Moth was ideal for training new pilots during World War II. It was used as the primary training aircraft for all Commonwealth countries under the British Commonwealth Air Training Plan, which was signed into effect on December 17, 1939.

A Mosquito (Canadian Forces photo)

In addition to Tiger Moth production, 1,133 Mosquitos were built at Downsview during the war. The Mosquito was a lightweight nighttime bomber noted for its speed; until 1944, the Mosquito was the fastest plane in World War II. The FHBRO report notes that “its importance to the Allied war effort may be gauged by the fact that a museum has been established in England devoted solely to this aircraft. ‘I turn green with envy when I see the Mosquito,’ commented the German Reichmarshall Hermann Goering.”

Mosquito Servicing and Descriptive Handbook (City of Toronto Archives, Fonds 70, Series 340, Subseries 8, File 11

Also of note was the Avro Anson, an aircraft obsolete for combat by World War II, but useful as a training aircraft. Anson parts, both used and new, were shipped to Downsview from Great Britain for assembly; according to the Canadian Air & Space Museum website, 375 Ansons were assembled at Downsview during the war.


De Havilland had over 7,000 employees at Downsview during the war, about one-third of whom were women. Although much of this labour force was let go immediately after the war, de Havilland remained a major Canadian airplane manufacturer, soon shifting more towards the production of civilian aircraft. Amongst the significant airplanes produced and tested at Downsview in the post-war years were the Chipmunk and the Beaver. The Chipmunk was used as an RCAF training plane for many years after the war, whereas the Beaver was a versatile plane noted for its contribution in helping to open up the Canadian north.

Women building the Mosquito (Library & Archives Canada)

World War II saw Toronto, and indeed much of southern Ontario, grow as an important industrial area. This prompted the need for defence, as Toronto and its environs otherwise represented a vulnerable strategic target. In the spring of 1946, 400 Squadron reformed at Downsview, and until the 1990s, parts of the site were used as a military base. In 1950, 411 Squadron also began using the site and from 1956 until 1964, 436 Transport Squadron was also stationed at Downsview.

In 1954, de Havilland sold their Downsview land to the Canadian government, relocating to a new site a few kilometres to the south, near Wilson Avenue. De Havilland was not entirely done with their old Downsview location, however, leasing some of their old space back from the Canadian government.

In June of 1954, the Department of National Defence opened the new home of the RCAF’s No. 1 Supply Depot at Downsview. According to a 1981 publication specifically about the Depot, its role was “to provide third line (wholesale) supply services to sea, land, and air elements of the Canadian Armed Forces. To accomplish this role, more than two million cubic feet of storage space is provided in addition to adequate adjacent spaces for receiving, shipping, internal handling, packaging and preservation, administration and employee facilities.” Structures indicates that when opened, the main depot building was one of the largest buildings in North America.

CFB Downsview closed in 1996, prompting the process of re-purposing much of Downsview, including the original land and primary building first occupied by de Havilland in 1929.

Since de Havilland commenced operations at Downsview, there have been many changes to the buildings on the site; identifying the precise uses of and alterations to each individual building is difficult, but not entirely impossible.

Downsview Site (Canadian Air & Space Museum)

The Canadian Air & Space Museum has been in a facility often referred to as “Plant #1,” constructed in five different stages between 1929 and 1944. According to the FHBRO report, the initial 1929 section of the building featured several workshops, administrative offices, and a hangar. In his 1983 book,  The de Havilland Canada Story, historian Fred W. Hotson says that this building offered 20,000 square feet of space, and that it initially faced north towards where Sheppard Avenue then was, 50 yards west of where the portable hangar from De Lesseps Field was re-erected. This first section of Plant #1 was one of several buildings on the site designed by noted architects Mathers & Haldenby, whose other contributions to Toronto include dormitories for Upper Canada College, several buildings for the University of Toronto, the U.S. Consulate, and numerous other buildings of industrial, commercial and residential design.

In the late 1930s, a section was added to the east for the assembly of Tiger Moths; the increased contract for Tiger Moths led to a second addition in 1940. The two other substantial additions came later in the war, demonstrative not only of the rapid expansion of the site, but of the rapid growth of the Canadian airplane manufacturing industry.

There have been no known major additions to Plant #1 since 1944, although the building has been re-purposed numerous times. Following the war, Plant #1 remained central to de Havilland’s use of the Downsview site. The Canadian Air & Space Museum’s website indicates that the prototype of the Chipmunk was developed in Plant #1 and first flown at Downsview in 1946; the website also states that in 1947, Plant #1 was where the first Beaver was assembled.

Plant #1 was used in the 1950s and 1960s by de Havilland’s Guided Missile Division (later renamed Special Products Applied Research) where, according to the Canadian Air & Space Museum’s website “secret work was hidden from public view with the new RCAF base.” This work is believed to include the development of Canada’s first spacecraft, the Alouette I, along with the STEM antenna which was used extensively in the U.S. space program.

After this special division left the Downsview site in the 1960s, Plant #1 was used by the Canadian military for a variety of purposes, including as a warehouse and office in connection with the DND’s supply depot. The Canadian Air & Space Museum’s website indicates that Plant #1 was used again for manufacturing as late as the mid-1990s, when it was used by Bombardier Aerospace (who by this time had acquired de Havilland Canada) to construct fuselages for aircraft ordered by the U.S. army.

Until recently, home to the museum (Canadian Air & Space Museum)

Plant #1 is especially rare in that it spans a long period in Canada’s aviation history, from the pioneering days of the late 1920s, through World War II into the era of post-war aircraft production. The FHBRO report says that Plant #1 represents “the early development of the aircraft industry in Canada, this country’s contribution to the Allied war effort, and the impact of war on the Canadian economy… [T]his structure would appear to be more directly implicated in all three of these themes than any other in the [Downsview] complex. No attempt has been made to inventory other sites which might illustrate one or more of these themes but, in the context of existing knowledge regarding aircraft manufacturing sites, it is difficult to conceive how another structure in federal government hands could do so.”

Thank you to Rob Godwin of the Canadian Air & Space Museum

For more information:
Timeline of Plant #1 from the Canadian Air & Space Museum:
Rogers Structures episode on Downsview (airspace history section begins at 14:30):
De Havilland in Canada, by Fred W. Hotson. Toronto: CANAV Books, 1999.
The de Havilland Canada Story, by Fred W. Hotson. Toronto: CANAV Books, 1983.
FHBRO report from 1990.…

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