Inbound aircraft to London Heathrow Airport typically follow one of a number of Standard Arrival Routes (STARs). The STARs each terminate at one of four different RNAV waypoints (co-located with VOR navigational aids), and these also define four "stacks" where aircraft can be held, if necessary, until they are cleared to begin their approach to land. Stacks are sections of

airspace Airspace is the portion of the atmosphere controlled by a country above its territory, including its territorial waters or, more generally, any specific three-dimensional portion of the atmosphere. It is not the same as aerospace, which is the ...

where inbound aircraft will normally use the pattern closest to their arrival route. They can be visualised as invisible helter skelters in the sky. Each stack descends in 1000 ft (300 m) intervals from 16,000 ft (4,000m) down to 8000 ft (2,100m). If these holds become full, aircraft are held at more distant points before being cleared onward to one of the four main holds.

The stacks

Bovingdon

The Bovingdon stack (BNN) is for arrivals from the north west. It extends above the village of Bovingdon and the town of Chesham, and uses the RNAV waypoint BNN (co-located with the BNN VOR), which is situated on the former RAF Bovingdon airfield.

Biggin Hill

The

Biggin Hill Biggin Hill is a settlement on the south-eastern outskirts of Greater London, England, within the London Borough of Bromley. Within the boundaries of the historic county of Kent, prior to 1965 it was also in the administrative county of Kent. ...

stack (BIG) on the south east edge of Greater London is for arrivals from the south east. It uses the RNAV waypoint BIG (co-located with the BIG VOR), which is situated on

London Biggin Hill Airport London Biggin Hill Airport is an operational general aviation airport at Biggin Hill in the London Borough of Bromley, located south-southeast of Central London. The airport was formerly a Royal Air Force station RAF Biggin Hill, and a sm ...

Lambourne

The Lambourne stack (LAM) in Essex is for arrivals from the north east. It uses the RNAV waypoint LAM (co-located with the LAM VOR), which is situated adjacent to Stapleford Aerodrome.

Ockham

The Ockham stack (OCK) in Surrey is for arrivals from the south west. It uses the RNAV waypoint OCK (co-located with the OCK VOR), which is situated on the former Wisley Airfield. During typical easterly operations, the proximity of arrival traffic via OCK requires departures from Heathrow's runway 09R towards the Compton VOR (CPT) to follow a non-standard departure procedure.

Developments

The arrival procedures are being revised since 2014 to reduce stacking by introducing variable speed limits and alternative holding procedures.

Incidents

On 1 December 2003 at 6am, a major disaster in the stack was narrowly avoided. An

air traffic controller Air traffic control specialists, abbreviated ATCS, are personnel responsible for the safe, orderly, and expeditious flow of air traffic in the global air traffic control system. Usually stationed in air traffic control centers and control ...

was blamed by a later inquiry for misdirecting traffic when he ordered a

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into a level of the Bovingdon Hold (or stack) already occupied by a similar

British Airways British Airways (BA) is the flag carrier airline of the United Kingdom. It is headquartered in London, England, near its main hub at Heathrow Airport. The airline is the second largest UK-based carrier, based on fleet size and passengers ...

plane. The two planes, carrying 500 passengers, flew within 600 vertical feet (180 m) of each other.

References

External links

*{{cite web, url=http://avsim.com/atco/dayinthelife.htm , title=ATCO: Day in the life (a real life transcript of air traffic control in the area) , accessdate=2004-11-10 , url-status=bot: unknown , archiveurl=https://web.archive.org/web/20080229134124/http://avsim.com/atco/dayinthelife.htm , archivedate=29 February 2008
London 24 - Layers of London air traffic
NATS, 2014 Aviation in London Aviation in England Heathrow Airport