asked around with african colleagues- is lobito in Zaire?- then people would mostly speak lingala???
my african colleagues tell me people would probably not have a word but probably use avion- the French word-
but I am not giving up as yet!(unless it is Moz or Angola- since you are translating from Port..)

Hi Sandra,

the following are the entries I found :

aeroplane, airplane: vliegtuig

Source: Freedict.

Bom trabalho