Hi Jono,
English only while using checklists/flows/QRH etc. Spanish is the language with ATC in South America except in Brazil, in which case it is english. If you were to join on the Airbus family you would be limited to this operating area. All normal and operational conversations with other crew members, ground staff, airport staff and such would be in spanish.
Saludos and good luck,
SEQU
Last edited by sequ; 18th Aug 2019 at 19:56.