Character encoding for openair files

Hi, I have an airspace file in openair format. The character encondig is ISO-8859 and has the "ñ" letter and accented vowels. FiF doesn't show that symbols wright. What character enconding expect the app?
Happy landings in 2023! Thanks for your support in 2022.
https://www.funair.cz/domains/funair.cz/forum/
https://www.funair.cz/domains/funair.cz/forum/viewtopic.php?f=4&t=5691