Flight board data, for short (4)

I believe the answer is:
etas
(Other definitions for etas that I've seen before include "Makarios' letters" , "Characters from overseas" , "Foreign characters" , "Greek characters" , "Characters in Greece" .)
I believe the answer is:
etas
(Other definitions for etas that I've seen before include "Makarios' letters" , "Characters from overseas" , "Foreign characters" , "Greek characters" , "Characters in Greece" .)