My guess is that they only hire brazilian nationals?
Not entirely true, it would depend very much on your specialisation and the availability of suitable Brazilian candidates, but Embraer does employ foreigners when necessary. Assuming equivalent qualifications (often the hardest part, is your degree recognised in Brazil?) their preference is obviously for Brazilians first, Portuguese speakers second and then any other qualified individual.
The more exotic your specialisation, the greater chance you have.
TTFN