London Terminal Control Centre

The London Terminal Control Centre (LTCC) was an air traffic control centre based in West Drayton, in the London Borough of Hillingdon, England, approximately 2.5 miles (4.0 km) north of London Heathrow airport. Operated by National Air Traffic Services (NATS) it provided air traffic control services to aircraft arriving and departing from six London airports, one Royal Air Force station, plus en-route services to other aircraft that entered its airspace. Internally within NATS it is usually known by the initials TC. The civilian part of the West Drayton site closed in November 2007, when its functions moved to Swanwick, Hampshire. 'TC' and 'AC' (London Area Control Centre) remain separate organisations but now share the same site.

Unlike New York TRACON, LTCC uses Class A airspace. Therefore, VFR operation is prohibited.

History

The centre was opened as RAF West Drayton, a military air traffic control facility, located roughly midway between the then London airport (now London Heathrow) and RAF Northolt. The civilian control function present at this centre in 1971 became the London Air Traffic Control Centre (LATCC), operating alongside the RAF. In the early 1990s the 'Central Control Facility' (CCF) was formed within the centre to provide terminal control services to aircraft arriving at and departing from the main London airports, subsuming the existing terminal sectors in preparation for the arrival of the London area airport approach units. For this, the CCF Display and Information System (CDIS) was developed.

In 1992 the Heathrow and Gatwick approach control units moved to West Drayton to share facilities with the CCF. The CCF and the two approach control units were moved into the new Terminal Control room in 1995, and thus became a separate entity to Area Control. To reflect the fact that there were now two civil control rooms (Area and Terminal) the centre was renamed the London Area and Terminal Control Centre, whilst retaining the same LATCC abbreviation.

RAF West Drayton formally closed in the 1990s, though military personnel remained on site until 2008.

In 1995 Stansted approach control, soon after to be renamed Essex Radar, moved to West Drayton to take their place in the TCR. In 2002 Luton approach control also moved in. In the same year, the Area Control function moved from West Drayton to the new London Area Control Centre (LACC) in Swanwick, Hampshire. The West Drayton facility was renamed the London Terminal Control Centre (LTCC - though still pronounced "latsea") at this time. In 2004, Thames Radar (London City and Biggin Hill radar approach control) moved in from its former home at Heathrow Tower.

Civilian operations at the centre ceased in November 2007, after Terminal Control moved to Swanwick to be reunited with Area Control. Military operations moved to a new control room also at Swanwick in January 2008.

One of the last PDP11 based air traffic control systems from LATCC is now on display at The National Museum of Computing.

TC today at the NATS Swanwick, Hampshire facility

Terminal or TMA sectors

TC-based controllers provide air traffic services within the London Terminal Control Area (TMA). This airspace is split into two groups or banks, TC North and TC South, which not only relates to the position of the airspace sector relative to London Heathrow, but also the direction in the Terminal Control Room in which that sector's controllers face when at their radar consoles. TC North is further split into North East (3 sectors) and North West (2 sectors). TC South is further split into South East (2 sectors) and South West (3 sectors). All sectors have the RT callsign "London Control".

TC North

TC North West
- North West Departures (119.775MHz): Stansted & Luton departures to the west, London City departures to the north-west or rest, and Heathrow departures to the north-west.
- TC Bovingdon (BNN): Heathrow arrivals from the north, north-west, and west, via the Bovingdon (BNN) STAR.
TC North East
- North East Departures (118.825MHz): Stansted & Luton departures to the east, London City departures to the north, and Heathrow departures to the north-east.
- TC Lambourne (LAM): Heathrow arrivals from the north-east, via the Lambourne (LAM) STAR.
- TC LOREL: Stansted and Luton arrivals from the north, south, and west, via the LOREL STAR.

TC South

TC South West
- South West Departures (134.125MHz): Heathrow departures to the west or south-west, Gatwick departures to the west.
- TC Ockham (OCK): Heathrow arrivals from the south and south-west, via the Ockham (OCK) STAR.
- TC WILLO: Gatwick arrivals from the north, west, and Heathrow (joining the STAR at Midhurst (MID)), via the WILLO STAR.
TC South East
- TC Biggin (BIG): Heathrow departures to the south-east, Gatwick departures to the east and Heathrow (joining the STAR at Biggin (BIG)), and Heathrow arrivals from the south-east via the Biggin (BIG) STAR. (This sector can be better understood as a combination of a theoretical South East Departures sector and a theoretical TC Biggin (BIG) sector, similar to the BNN, LAM, and OCK sectors. Due to the more congested and interlaced nature of this sector, such separate departure and arrival sectors would be unfeasible.)
- TC TIMBA: Gatwick arrivals from the south, east, and Essex clutch (Stansted, Luton, Southend, and Cambridge), via the TIMBA STAR.

At its busiest, each sector will have a radar controller. When it is quieter sectors are "bandboxed" with one controller operating multiple sectors, until at night there may only be one controller operating the whole bank. Each bank will also have up to two further supernumerary controllers acting as co-ordinators (to liaise with other sectors and other units, and generally assist the radar controllers), and up to two assistants to prepare flight progress strips, operate computer systems and assist with flight data duties.

Aircraft departing Heathrow, Gatwick, Luton (to the north or west only), and Stansted mostly depart on a free-flow principle: the radar controllers do not release each individual flight for departure, they just receive a pre-note via a computer system that the flight is pending. This cuts down on inter-unit co-ordination and allows the tower controller at the airport to decide the most efficient departure order. In many cases the aircraft's Standard Instrument Departure (SID) routing does not conflict with the approach sequence of aircraft arriving at the airport, so the airport's approach control does not need to handle the aircraft and it is transferred straight to the TMA controller on departure. The TMA controllers then climb the departures through the arrivals to the airports that they are also working.

Arrivals to the London airports are handed over from LACC at Swanwick or the TC en-route sectors, usually following STARs and are descended against the departing traffic, sorted out into different levels, and routed to various holds (generally at the end of STARs), where they will hold until the approach control units are ready to position them into an approach sequence to land.

Approach sectors

The Approach Control units for the five major London airports are also controlled from TC, plus the radar approach services for Biggin Hill. Each approach unit has more than one sector. The majority of the work for the approach units is controlling the sequence of aircraft making an approach at an airport from the holds until established on final approach about four miles away from the airport. The approach units also handle some aircraft departing from the airport, when that aircraft's departure conflicts with the approach sequence.

Slightly unusual to the approach sectors at TC is that some of them can be staffed by two controllers at a time, making transmissions on the same frequency.

LTCC Approach Sectors
Unit	Sector	RT Callsign	Role
Heathrow	Intermediate Director North/TC Heathrow North	Heathrow Director	Initial approach sequencing from the north for Heathrow and RAF Northolt
	Intermediate Director South/TC Heathrow South	Heathrow Director	Initial approach sequencing from the south for Heathrow and RAF Northolt, IFR departures via CPT from 09L/09R
	Final Director	Heathrow Director	Final approach sequencing
Gatwick	Intermediate Director/TC Gatwick	Gatwick Director	Initial approach sequencing
Gatwick	Final Director	Gatwick Director	Final approach sequencing, IFR departures via SFD from 08L/08R & VFR departures
Stansted	Intermediate Radar/TC Essex	Essex Radar	Initial approach sequencing for Stansted and Luton
Stansted	Final Director	Stansted Director	Final approach sequencing, IFR departures via NUGBO, UTAVA, and BKY & VFR Departures
Luton	Intermediate Radar/TC Luton	Luton Radar	Initial approach sequencing, IFR departures via OLNEY & CPT from 08, Non-Airway IFR Departures
Luton	Final Director	Luton Director	Final approach sequencing, VFR Departures
Thames	Intermediate Director/TC Thames	Thames Director	Initial approach sequencing for London City and Biggin Hill, Southend departures, Heathrow VFR helicopters
	Final Director	Thames Director	Final approach sequencing for London City and Biggin Hill
	Special VFR	Heathrow Radar	Low-level VFR and SVFR traffic around London Heathrow

En-route sectors

TC is slightly unusual for a Terminal Control Centre in that it also has a number of en-route sectors responsible for lower levels of airspace on the outside, on top of and in the outer parts the TMA. These sectors not only include Class A airspace in the TMA and surrounding CTAs below FL195, but also Class C airspace above FL195. These are controlled from TC because they mainly feed traffic into and out of the main London airports. They are grouped as TC East (4 sectors), TC Midlands (4 sectors) and TC Capital (2 sectors). TC Midlands is somewhat of a hybrid since it also interacts directly with airports and the aircraft departing from them in the same way as the TMA sectors.

TC East

TC DAGGA: London TMA departures to the east, towards and overflying Europe.
TC REDFA: London TMA departures to, and arrivals from, the east - mostly for Stansted & Luton.
TC SABER: London TMA arrivals from the east.
TC JACKO: Mostly ABBOT (Stansted/Luton) and London City arrivals from the east.

TC Midlands

TC COWLY W: London TMA & Birmingham Arrivals from the North-West (via/near COWLY).
TC COWLY E: London TMA Arrivals from COWLY W.
TC WELIN W: London TMA Departures from WELIN E.
TC WELIN E: London TMA Departures to the North-West and East Midlands (via/near WELIN).

TC Capital

TC Compton (CPT): Traffic passing through the western London TMA travelling North-South or vice-versa (CPT is a major VOR within this area
TC VATON: Traffic passing through eastern London TMA travelling North-South or vice-versa (VATON is an intersection waypoint within this area, now out of use).

All sectors have the RT callsign "London Control". TC East's airspace adjoins the international boundary with Amsterdam and Brussels airspace.

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External links

Our control centres, NATS
"NATS - A Case Study (presentation)" (PDF). British Computer Society. 11 January 2005. Retrieved 14 December 2014.

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