Published on October 8th, 2018 | by Mark Dwyer


Software Issue caused Problem at Shannon ACC

The result of an investigation into a systems failure at the Shannon Area Control Centre (ACC) at Ballycasey has found “an irregular software occurrence” was to blame. The event happened on the evening of 2nd October which lead to air traffic controllers losing many systems. Despite many media reports, the radar continued to function at all times and controllers were able to switch immediately to the backup system to control traffic. The backup system is primarily used to get existing aircraft under radar control on the ground, or out of Irish airspace and as a result, the decision was made to go to a zero flow rate in the Shannon FIR (excluding the Dublin area) until the problem was resolved.

In a statement the IAA said “When the technical issue occurred on Tuesday evening, we are satisfied that the back-up system and contingency planning worked as required.  This ensured that we restored full service in a safe and timely manner and disruption to aircraft was minimal. The IAA continues to invest in its state-of-the-art air traffic management system and in the development of our staff, to deliver a world-class service to our airline customers.”

The zero flow rate luckily happened at a relatively quiet time when there was little Transatlantic traffic although some restrictions were put in place. For North Atlantic westbound oceanic traffic arriving at KORD/Chicago, KDTW/Detroit, KBOS/Boston and Canadian airports on Wednesday between 10-20 UTC, Boston ACC requested that aircraft file on Oceanic Track GOLF or north of Track GOLF. There were a number of cancellations in and out of Cork and Shannon however some flights diverted to Dublin before continuing on to Shannon after the restrictions were lifted.

The IAA also went on to clarify some statements that were published by some media outlets:

  • The technical issue which occurred was not a radar issue. Full radar coverage was maintained at all times.
  • The technical issue involved a module on our ATC system which affected the performance of this system. The IAA took the decision to move to its back-up systems in order to maintain a full and safe service to aircraft.
  • The IAA must follow a regulatory procedure when transferring to the back-up system. This procedure ensures safety of operations; however it necessitated the restrictions on traffic flow which occurred on Tuesday evening.
  • The back-up system is a full replica of the IAA’s main ATC system. This allowed the IAA to provide a full and normal, safe ATC service once transfer to this system was completed.

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About the Author

Mark is an airline pilot flying the Boeing 737 for a major European airline. In addition he is also a Type Rating Instructor, Type Rating Examiner and Base Training Captain on the B737. Outside of commercial flying Mark enjoys flying light aircraft from the smallest 3 Axis microlights up to heavier singles. He is also an instructor and EASA Examiner on single engines and a UK CAA Examiner. He flies the Chipmunk for the Irish Historic Flight Foundation (IHFF). Mark became the Chairman of the National Microlight Association of Ireland (NMAI) in 2013 and has overseen a massive growth in the organisation. In this role he has worked at local and national levels. In 2015, Mark won ‘Upcoming Aviation Professional Award’ at the Aviation Industry Awards sponsored by the IAA. Mark launched this website back in 2002 while always managing the website, he has also been Editor and Deputy Editor of FlyingInIreland Magazine from 2005 to 2015.

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