Occurrence
On 20 October 2023, a Ryanair Sun S.A. Boeing 737-800, registration SP-RKI, was operating a scheduled flight from Gothenburg Landvetter Airport (ESGG) to Gdańsk Lech Wałęsa Airport (EPGD) in Poland. At 09:43 UTC, immediately after takeoff, the aircraft collided with a medium-sized bird, identified as a kestrel. The bird was ingested into engine number 1. The flight crew felt airframe vibrations, but both engines continued to operate normally. The crew decided to continue the flight to the destination.
During the climb, vibration of engine number 1 increased to a value exceeding 4.0 units. The climb was halted at flight level FL150. The crew performed the Quick Reference Handbook (QRH) procedure for "High Engine Vibrations – Non-Icing Conditions." The procedure did not require an immediate landing at the nearest suitable airport. The climb was resumed, and the aircraft reached cruising altitude FL300.
While at FL300, the crew assessed the meteorological conditions at the destination. The forecast for the planned landing time indicated wind gusts up to 25 knots (EPGD 201100Z 08015G25KT 6000 - RADZ BKN005 04/03 Q1000). The crew considered these conditions unsuitable and decided to divert to the alternate airport, Olsztyn-Mazury Airport (EPMO).
Investigation Findings
The entity investigating the incident concluded that the diversion decision was unjustified and lacked operational justification. The investigation noted that the diversion extended the flight time by 20 minutes relative to the planned flight time for the ESGG–EPGD route, which exposed engine number 1 to potential damage. The aircraft landed at EPMO without further incident.
Post-flight inspection of the aircraft confirmed a bird strike and revealed deformation of several fan blades of engine number 1.
Cause
The cause of the incident was the bird strike, which resulted in deformation of the fan blades of engine number 1.
Safety Actions
The operator’s chief pilot conducted a debriefing with the flight crew regarding the in-flight decision-making process.