5.200 in the Radio Frequency Table Allocation of Ireland.

Content Type: ITU FOOTNOTE
Title: 5.200
Description: In the frequency band 117.975-137 MHz, the frequency 121.5 MHz is the aeronautical
emergency frequency and, where required, the frequency 123.1 MHz is the aeronautical frequency auxiliary to 121.5 MHz. Mobile stations of the maritime mobile service may communicate on these frequencies under the conditions laid down in Article 31 for distress and safety purposes with stations of the aeronautical mobile service and the aeronautical mobile-satellite service. (WRC-23)
Source: https://search.itu.int/history/HistoryDigitalCollectionDocLibrary/1.43.48.en.101.pdf