What happened
On August 11, 2017, a Ryanair Boeing 737-800 (B738) was operating a flight from Dublin (EIDW) to Bydgoszcz (EPBY). While approaching Bydgoszcz, the aircraft entered a holding pattern because the prevailing weather conditions were below the required landing minimums. Due to the inability to land at the original destination, the captain decided to divert the flight to Poznań (EPPO).
Air Traffic Services in both Bydgoszcz and Poznań coordinated the flight plan modification to facilitate the diversion. The aircraft landed at Poznań at 21:10 UTC. This arrival occurred during a period of local noise restrictions, which are in effect between 21:00 and 05:00 UTC.
The investigation
The investigation examined the coordination between airport operational services and air traffic control. The Airport Duty Manager (DOPL) at Poznań notified the Tower controller (TWR) that the airport had reached its capacity for night-time operations, as the 13th operation was scheduled for a window that only allowed for 12 operations between 22:00 and 06:00 local time.
To manage the arrival, the Tower controller contacted the Approach controller (APP) to inquire about the aircraft's fuel status. The crew reported having 4 tonnes of fuel remaining, which provided approximately 20 minutes of additional flight time, with a maximum endurance of 1 hour and 50 minutes. Based on this information, the decision was made to proceed with the landing at Poznań.