The unit was equiped with three frequencies, 135.85 and 126.85 that were Scottish ATCC Sector 24 & 25 (high level) and 132.9, a discrete frequency for the Irish Sea. The frequencies 135.85 and 126.85 had a direct intercom link between the Scottish proceedural controllers and the Ulster Radar controllers. The 132.9 frequency was exclusive to Ulster Radar. In addition there were direct phone links to Scottish Controllers and Assistants along with direct lines to adjacent units also covering both controllers and assistants positions. Communications maintainence was carried out by NATS engineers who traveled from Belfast Aldergrove.
Flight data was received at the unit by Electrowriter from Scottish, London and formerly Preston ATCCs. A transmitter unit at these centres was used by assistants at the centres to write the the flight data (aircraft type, callsign, speed, level, estimate for the boundary reporting point etc) and when the pen was mover to the top right of the page the hand written data would be transmitted down a direct phone line to Ulster and a receiver unit would begin to write the data there and then move the paper out of the machine to be torn off. Data was then transferred by an assistant to a perspex flight progress strip using a coloued chinagraph pencil (red for eastbound and white for westbound) and placed in in the appropiate pending slot. All data received was regarding live aircraft, ie. aircraft in flight. This estimated time and any level change for the boundry point was then updated by phone before the aircraft came on frequency.
Unlike the ATCCs where the flight progress strips were positioned on the ops board at the last reporting point the aircraft checked, Ulster ran a system of moving these strips to the next estimated reporting point. As an example if an aircraft reported passing Wallasey (WAL) at 09 and estimating IOM at 19 the ATCC strip would be positioned in the WAL bay on the board but Ulster would position the strip in the IOM bay. This made potential conflicts easier to spot and resolve.
Those who have seen the modern day radars at ATCCs will know that each blip is followed by data for that aircraft (flight level, SSR code, etc) on the display. The SSR at Ulster was not that technically advanced. The radar display showed the aircraft as a blip and the fact that it was using a SSR asigned code was indicated by the blip being followed by a slash. Two slashes meant the aircraft was "Squawking" ident and if three or four slashes appeared behind the blip the aircraft had some form of emergerncy. Various SSR codes, such as those for the units civil and military sections along with adjacent civil and military units codes and including the emergency codes, were selected on a box on top of the radar consol. If the radar controller wished to interrogate the radar return to check what flight level the aircraft was a special light pen had to be placed on the blip. When the radar beam passed the selected aircraft the aircraft's assigned code and flight level were displayed on the SSR code box above the radar consol. All assigned SSR codes consisted of 4 digits and the first two digits indicated the unit handling the aircraft while the remaining to digits refered to the aircraft. At that time the SSR codes or Squawks as they were called for Ulster and neighbouring radar units were as follows:
Ulster Civil 23##; Ulster Military 74##; Lindholme Civil 27##; Lindholme Military 46##; Border Civil 70##; and Border Military 61##.
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