AIR TRAFFIC CONTROL CENTRE OPERATIONS
By mid 1931, the control tower at Cleveland had established a set of procedures which required aircraft to advise arrival and departure times of aircraft from various departure points and to report over intermediate points. A map of the section under monitor by the tower was kept on a table in the tower. It was covered with heavy plastic in which were holes at cities representing the usual reporting points and the arrivals and departures were pegged in these holes according to reports received via telephone or airline office reports.
As the Cleveland orders read:
"...When the aircraft was expected within 3 to 5 miles of the tower, then the controller would transmit the ceiling, visibility, wind direction and velocity and number of aircraft expected to arrive at airport within the next ten minutes and the number in the air around the airport...."
This was the beginning of a crude form of en route control. Later, the controller used a blackboard to post the expected fix crossings and keep track of the aircraft in his area. To avoid the need to erase and rewrite (and sometimes smudge) the sequence someone got the bright idea of sawing the blackboard into slats that could be arranged as required to show the air traffic picture.
In 1938 a Mr. John Huber of Washington Centre designed the first Flight Progress Board using paper strips. He brought it into Washington Centre in 1938 and said, "I have built this holder. You guys figure out how to use it!" Up until that time, all efforts had been aimed at improving the blackboard, which had not really improved the system or made it easier to keep track of aircraft expeditiously nor speedily. That same year, Washington Centre devised a standard Centre layout with flight progress boards, paper strips, a horizontal map display with shrimp boats and the "A" and "B" working positions. Radio communication with aircraft was by Aeradio Stations and Airline companies who maintained radio contact with their aircraft. This was the standard centre layout for Canadian and United States Centres until the 1950s.
In this book "BONFIRES TO BEACONS," Harry Komons describes the Air Traffic Control Centre operations:
"Each station was manned by a crew of five - a manager, assistant manager, and three controllers. The Centres operated 16 hours a day, from 0800 until 2359, but the availability of the air traffic control services generated more need (and traffic) and the centres eventually went to a 24-hour schedule. The crews worked overlapping shifts with the largest on-duty controller contingent being, three, during periods of heaviest traffic and the smallest, one, during midnight of holiday hours.
Each station was equipped with a large blackboard, a large table map-covered with plastic, a teletype machine, and a telephone. Flights were posted on the blackboard, which detailed their progress and their estimated time of arrival and altitude over designated geographical fixes. Basic information from the board was transferred to the map, on which all airways were plainly marked. Small brass markers shaped like shrimp boats, one for each flight in the control area, dotted the map. Each marker was equipped with a clip, to which could be attached a slip of paper. The controller noted on the paper the airline, the flight number, the flight's time of departure and cruising altitude. Placed in positions on the map corresponding to their flight progress, these markers showed by their pointed ends the direction of flight and gave a reasonably clear picture of what would probably take place as incoming aircraft converged around the airport. Each marker was moved every 15 minutes to conform to the actual or estimated progress made by the aircraft.
When the controllers were on duty, each performed a distinct function. The "A" controller issued instructions to aircraft, including all clearances and maintained the dispatch board as well as the inbound flight log. The "B" controller or coordinator, handled the weather sequences, maintained two other logs and positioned the shrimp boats as necessary to update the map. The "C" controller or calculator, calculated the speed of incoming aircraft, estimated times that they would arrive at fixes, and entered these times on the blackboard. During periods of low traffic volume, one man fulfilled all three functions. When two men were on duty, the functions of the coordinator were split.
Only passive control was exercised in good weather. Nevertheless, their progress was followed as if they were under active control and information passed to other flights within 15 minutes of the final approach fix. Aircraft came under active control only during instrument flight. ATC's function was seen as keeping en route airline traffic separated and flowing in such a manner that the flights arrived at destination in an orderly sequence. The government realized that not only transport flights needed air traffic control but safety required that all instrument flights proceed from origin to destination in a prescribed manner."
In 1939, Washington Centre experimented with an automated flight data posting board, which was based on the Teleregister Company's automated displays in stock broker's offices. A prototype was installed in the Centre and a long-term evaluation began. Since there was little technology available during the war years and few, if any, spare parts, the "automatic white elephant" faded into obscurity. During the war years, landline capability expanded, but no effort was aimed at direct pilot-controller communications even though some Centre staff were calling for this innovation.
CANADIAN AIRPORT CONTROL OPERATIONS
Canadian Air Traffic Control operations followed the lead of the United States. In 1939, the first Department of Transport Tower was opened at St. Hubert. This was followed by the opening of towers at Toronto, Ottawa and Vancouver in 1940. The Secretary of State for Air Sent a memorandum to DOT pointing out the need for a system of control for these four airports and authorizing DOT to start action to recruit controllers. The first ten ab initio controllers were trained at St. Hubert through on-the-job operations. (See Appendix E)
CANADIAN AREA CONTROL CENTRES
The Department of Transport (DOT) opened the first Canadian Area Control Centre in Toronto in late 1940. Operations were conducted in a similar manner to that of the United States Control Centres. By 1942, Area control Centres were also opened in Montreal and Edmonton under DOT control. In 1943, the RCAF, due to heavy United States Army Air Force flights along the North West Staging Route, took over the Edmonton Centre and also established centres in Vancouver and St. Jean P.Q. This was to provide air traffic control service to the airports of the War Home Establishment and ensure that Canadian operational aircraft on actual operational missions would receive war-level air traffic support by military controllers rather than civil controllers. In 1944, DOT completed cross-Canada ATC coverage by opening the Centre in Winnipeg.
Updated: November 28, 2004