The Radio Range

Communications and Aircraft Navigation

by Jack Chalmers and John Gilbert

Control of civil aviation operations in Canada was taken over in1936 by the Civil Aviation Branch of the newly created Department of Transport. A Radio Division, headed by Walter A. Rush, Controller of Radio was created within the Branch to develop radio navigational aids to serve the emerging needs of aviation across Canada[1].

The future of aviation in Canada at the time was synonymous with the plans of Trans-Canada Airlines. Speaking before The Empire Club of Canada on 27 October 1938 Philip Johnson, Vice-President, TCA recalled that the Trans-Canada Act had been enacted in April of 1937, but as late as July of that year the company existed purely as a corporate entity under a Board of Directors. To define Trans-Canada’s operational requirements an aerial survey was carried out over the route to be flown: from Vancouver, over the Rockies, East to Toronto and Montreal, then to the Maritimes terminating in Moncton. The survey would determine what airway facilities were available. It would propose plans for a radio communication system across Canada and would select the sites for the location of radio navigation stations. Trans-Canada would require fully usable fields, lighted for night flying, equipped with radio ranges, and other facilities necessary for safe navigation of aircraft under the existing techniques of flying.

Three parties played a crucial part in meeting Trans-Canada’s mandate for putting in place a transcontinental air line across Canada. First, the Company, charged with the operation and the organization of the actual flying. Second, the Government, represented by the Post Office Department and the Department of Transport. The Post Office furnished a major part of Trans-Canada’s payload, and the Department of Transport the ground facilities necessary to carry out the work. The third partner was the public – soon to discover the delights of flying.

Trans-Canada’s planes were equipped for radio reception. The pilot would navigate by following the "beam", a signal sent out from the Department of Transport radio range stations to be installed at about one hundred mile intervals across Canada. When on course the pilot heard a monotone but the minute he got off course he received an "A" signal or an "N" signal in Morse code.

The challenge for the Radio Division was to secure the funding (during the Depression), purchase the equipment and build the stations in some of the most inhospitable places in Canada. Initially, in 1936-37, seven old-type radio range stations were taken over from the Department of National Defence. These were partly remodelled until modern stations could be built at more suitable places. The first thirteen stations, completed in 1937-38, were, with the exception of St. Hubert, Quebec, all west of Winnipeg. Work began in that fiscal year on stations east of Winnipeg, many in places, such as Pagwa, Ontario which were remote and difficult to reach. Some of the locations, such as Porquis Junction, Ontario, had no local accommodation for the radio range staff. To meet this need sixteen dwellings, as well as a staff house at Carmi, BC, were built. Many technical problems had to be overcome. For example east of Winnipeg the resistance of conductivity to the ground was said to be about three times as great in the west as in the east. This cut down the effective range of the signal in the latter case and technical means had to be found to overcome the problem.

Despite the depression the Government undertook an aggressive program building airports and installing aids to navigation. By 1937 there were sufficient facilities for Trans-Canada Airlines, as Canada's "chosen instrument" in the field of aviation, to begin operating an intercity airmail and passenger service. By 1940, with the extension of passenger service to Moncton, Canada had a transcontinental day and night, all weather, mail and passenger service connecting its principal cities. The radio ranges, provided by the Department of Transport, were the principal aid to air navigation. The war years brought additional urgency to the establishment of radio ranges. A new circuit, started late in 1941, running from Edmonton to Alaska in conjunction with the construction of the Alaska Highway, was known as the Northwest Staging Route[2]. Radio Ranges were also used in support of the “Crimson Route” to England via Greenland and Iceland.

By the end of WWII Canada held fourth place world-wide in aviation yielding only to the USA, Britain and the USSR. Most Radio Ranges were, by this time, enhanced with two additional features: station location markers which sent an inverted cone straight from the ground which indicated to the pilot, by means of a light on the instrument panel, when the plane was directly above the range; and ranges were equipped to communicate directly with aircraft via radiotelephone. By the mid 50s there were some 94 radio ranges across the country.

While there was some variation in the equipment installed at each station, the basic Low Frequency Radio Range operated in the 200-400KHz band and had four 125-foot towers, set in a square. Diagonally opposite towers were fed with out-of-phase energy in what was known as the Adcock configuration. This produced a figure 8 pattern for each pair. The figure 8s overlapped and had four lobes. The "On Course" signal formed where two lobes overlapped. Each range was keyed in Morse code with its unique identifying letters.

A typical range[3] consisted of two 400 watt Marconi or Radio Receptor transmitters (if one failed the other came on automatically) a gonio unit and a control unit. The four steel 125-foot towers were fed from the transmitters through the gonio unit which produced the four courses. These courses were flyable to a distance of approximately 100 miles under normal conditions. A 10 watt cone of silence transmitter, operating at 75 MHz, informed the pilot when he was directly over the station. Each station was equipped with a power unit - a gasoline powered engine driving a 110 volt generator. A service road had to be built and maintained to access the communication transmitters which were located at a nearby transmitter site. 

Each of the radio range stations had a staff complement of radio operators. Radio schools across the country provided operator training and many experienced operators from Marine Services, the military and provincial services were attracted to the new service. Radio operators maintained a 24-hour vigil by monitoring all aids and notified the proper authorities when something went out of tolerance. The Radio Operator had a number of duties. Taking, and broadcasting, the hourly weather observations; taking pilot balloon or "pibal" observations (measuring wind direction and velocity using a gas-filled ballon tracked with a theodolite); checking the electrical generator; monitoring the signals of adjacent stations hourly, as well as his own radio range 24 hours a day.