Our Work



ACL commenced preparation for the London 2012 Olympics in 2009.

The initial phase included working with Atkins on behalf of the DfT to build a traffic forecast for the event for all traffic types (scheduled, charter and GA/BA) and to evaluate whether the forecast traffic could be accommodated within the existing South East England airport capacity.

Our forecast predicted that there would be 10,251 GA/BA movements, an additional 200 commercial scheduled and charter movements and 238 Head of State Movements. Based on the forecast 3 key areas emerged:

  • The London airports had sufficient capacity for the handling of the aircraft and passenger forecasts.
  • All airports within South East of England should be coordinated for the period of the Olympic Games
  • Flight plans should only be approved if the operator held corresponding airport slots.

Next Steps

Using the reports as its basis, the DFT conducted an industry wide consultation regarding coordination across 40 airports in SE England. Post consultation it was deemed that airports should be fully coordinated and that ACL should be the Coordinator. In August 2011 legislation via a Statutory Instrument was enacted which instructed the Olympic airports that they would be coordinated for the Olympics period, and that ACL as the coordinator was entitled to charge for any costs incurred. Charges would be based on a simple ‘charge per movement’ formula.

As mentioned above, 10,251 GA/BA movements across 40 airports were forecast to operate during the Olympics. As a result of this forecast, parking was highlighted as being a constraint at some airports.

A number of the smaller airports parking aprons were not marked out with specific stands and parking capacity therefore varied depending on the size of aircraft requesting parking. In the light of this complexity and the volume of bookings anticipated ACL concluded that the only practical booking process was for the airport to take the original enquiry from the operator, check the parking constraints and then book the required slot in the Online Coordination System (OCS).

ACL regularly communicated to both operators and airports in order to:

  • Summarise the volume of traffic forecast and the subsequent need for coordination
  • Describe which flights would be subject to coordination (all IFR but not VFR).
  • Outline how the coordination process would work.
  • Describe the Olympics slot booking process.
  • Highlight that penalties would be incurred if a flight plan was created that did not have a matching slot.

ACL staff attended a number of industry events (IATA conference, UK, and European business aviation meetings, CAA hosted events, NATS conferences, Eurocontrol (Air Navigation Provider)conferences and DFT events) to brief as many flight planners and operators as possible prior to the Olympics.

ACL also published bulletins and instructions describing the Olympics coordination process on industry websites and via industry publications such as NOTAM’s (Notice to Airmen) and AIP’s (Air Information for Pilots).

As part of the coordination process a Single Coordination Committee (SCC) was created chaired by the DfT and advised by ACL.  This met twice prior to the Olympics in order to agree the airports capacity declarations. The overall objective of the SCC was to ensure that the total airspace capacity over SE England was effectively managed, to ensure smooth operations for all operators.

The SCC’s capacity declarations were guided by advice from ACL, the CAA Safety Regulation Group and NATS.  In particular NATS used extensive simulation runs to provide guidance on how each airports capacity declaration would impact the efficient management of the airspace.

A number of system modifications were implemented to ensure robust and effective communications were maintained with operators, airports and industry bodies:

  • A two year (minimum length available) license to use the DFS Stanly slots to flight plan matching system was purchased
  • A dynamic update of ACL slot data into the DFS system for slots to flight plan matching was created
  • A dynamic update of flight plans data from Eurocontrol (Air Navigation Provider)into the DFS system was also created
  • A dynamic update of slot bookings data was supplied to Eurocontrol (Air Navigation Provider)by ACL.
  • Modifications were made to ACL’s coordination software (SCORE) and to the OCS to support GA/BA bookings at four letter code ICAO airports
  • A separate database and servers were created for Olympics bookings data to ensure data integrity was maintained at all times

The ACL Information Systems team implemented all of these changes in advance of the coordination period to ensure sufficient testing time was available. The overall performance of the ACL IT systems across the Olympics was 100% availability.

The majority of airports opened for bookings from 5 September 2011. In reality, the majority of the Olympics bookings were not made until 21 – 7 days prior to their date of operation.  This caused concerns at some airports as it proved hard to plan resources efficiently to meet demand.  ACL distributed latest bookings information on a regular basis during the build up to the Olympics to all airports and CAA, DfT, NATS and Eurocontrol. Below illustrates the bookings as we received them.


ACL thoroughly evaluated two slots to flight plan matching systems, one developed by Eurocontrol (Air Navigation Provider) and one by the German ATC provider DFS. Following this evaluation, the DFS Stanly system was selected as the preferred solution as it had following benefits:

It was available “off the shelf” as a proven system already in use within Europe

It had been used successfully during the 2006 World Cup in Germany.

It monitored both arrivals and departures.

Delivery – How we managed

ACL staff and airports operations staff were well briefed and able to handle the volume of slot requests effectively. The process of smaller airports checking parking capacity first, before making a booking on behalf of the operator in OCS, worked smoothly and there were no major issues.  OCS proved itself to be able to handle the extra volume of airports and bookings and there were no systems issues.

Total GA/BA bookings received over the period were 9,759, very close to the forecast of 10,251.

The movements were spread over the period in a similar pattern to that forecast, with peak demand days occurring around the opening ceremony, closing ceremony and 100m’s final.

Prior to the Olympics there was a great deal of focus on the expected high volume of HoS flights. In particular DfT were concerned there would not be sufficient parking in the South East to accommodate the expected volume of large aircraft. Heathrow airport had agreed with the DfT that it would not accept any HoS flights and Gatwick airport had restricted the parking capacity available for all ad hoc operations.

Prior to the Olympics, ACL worked closely with the airports, DfT and FCO to agree a robust and effective communications process for coordinating all HoS flights. ACL agreed individual constraints and approval processes with each major airports. Also, as mentioned previously, a dedicated HoS person was appointed for each day shift to provide DfT and FCO with a single point of contact, and to coordinate the flights across the Olympics airports.

The processes developed jointly with the airports, FCO and DfT worked well.

The DFS system was used intensively to ensure that operators obtained slots to match their flight plans. The DFS system generated 2,099 warnings of potential no slot or significantly off slot operations and ACL sent 835 warning messages.

The difference between DFS warnings generated and the actual number sent was driven by:

  • DFS generating a warning message which on investigation did not require action (e.g. DFS highlighted bmi coded flight plans as not having a matching slot as the slot was held under a BA code)
  • ACL staff proactively calling operators to alert them that an issue needed to be addressed, which resulted in less written warnings.

Of the 835 warning messages sent, 53% were for significantly off slot operations and 47% for operations without a slot. As can be seen from the table below, the majority of warning messages were generated at airports with a high number of GA/BA operations including Luton, Stansted and Farnborough.

Number of DFS warning messages sent by airport


Most operators responded quickly to the warnings and corrected the problem highlighted. However 353 flight plan suspension requests were made to Eurocontrol (Air Navigation Provider) (approximately 13 suspensions per day). Eurocontrol (Air Navigation Provider) was able to confirm back to ACL that a flight plan had been suspended within five minutes of receiving the request. Of those suspensions requested the majority were reinstated after the operator corrected the problem, with only eight operations not resolved before the flight operated.

The DFS system was in use on a 24hr basis, although experience soon showed that between 1800 and 0100 local time there were very few warnings to be processed. However, the number of warning never quite dropped to zero.  

Feedback Received

The following feedback has been received from the Olympics airports:

Thanks for all the help over this period (and the build-up to it!) Particularly those in the ACL call centre, who have always been helpful and able to answer all of our weird and wonderful questions.

Best regards Everyone from Biggin Hill Flight Operations

Not having used the ACL system before I did have a few problems.  A quick telephone call to your office and all of your staff were more than helpful and were always pleased to assist.

Thank you very much. Best regards  Jo Bampton Operations Cranfield Handling

Gatwick did not turn out to be so busy for the Olympics, but I think this was in part due to the 10 day slot ruling.  I worked very closely with both Robert and Fernando in the build up to the Olympics to ensure that GA did not break out of the allocated parking area that GAL had put into place.

I would like to thank both Robert and Fernando for all their help and assistance in the build up to and during the Olympics.  They made the whole event more manageable.

Kind regards, Jonna Mercercox Station Manager LGW  Signature Flight Support

We were pleased with the way things went even though it was not as busy as we expected. With regard to using OCS on a more permanent basis, we did look at it several years ago. The unscheduled nature of our business does not necessarily lend itself well to the system unless we had definitive number of restrictions per hour, which is something we do not yet require. However, as our business grows, this may be a way that we move towards. Certainly, we now have a better understanding of how OCS works and what benefits it could bring us, so will keep you in mind for a future strategy.

Roger Walker, Director Airport Operations, TAG Farnborough

Goodwood had limited movements through slot allocation but there were no issues with those that we handled.   Traffic throughput for people arriving for the actual Olympics was far lower than anticipated; instead our movement growth was from aircraft relocating to Goodwood from the ‘airspace constrained’ London catchment aerodromes. In terms of feedback about the ACL staff / processes, I think it worth mentioning my appreciation for members of your team who had time and patience in explaining the slot allocation process to some of the staff at Goodwood, many of whom had never worked in a slot controlled environment.

Kind regards,
Mark Gibb
Aviation Operations Manager
Goodwood Aerodrome

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