The Ayya Vaikunda Avataram (Tamil: அய்யா வைகுண்ட அவதாரம் - Incarnation of Vaikundar) is a festival celebrated by the followers of Ayyavazhi on the 20th day of the Tamil Month of Masi, the date on which the Ayyavazhi followers believe that Lord Vaikundar arose from the sea at Thiruchendur as the son of Mummorthies to destroy the evil spirit of Kali and transform the Kaliyukam into Dharma Yukam.
This is the only Ayyavazhi festival which is celebrated 'at a time' in all worship centres of Ayyavazhi on 19th Masi (3rd March), the day before the date of incarnation of Vaikundar.
Read more about Ayya Vaikunda Avataram: Processions, Chennai Procession, Celebration in Nagercoil, The Great Masi Procession, Other Processions