Shaykh Bin Baz was asked:
“A question remains [to answer] about a woman uncovering her face when being checked at the passport counter [, so may you answer it]?”
“If this is for the necessity of the travel, then she is pardoned for it. If it is not a necessity, then she does not uncover her face. However, if it is a necessity for the travel and the travel cannot be completed except by it so that they can take a picture [for example], then I do not know of any preventative for that in the necessity for travel. If it is not a necessity, then she does not uncover”. End translation.
Faisal Ibn Abdul Qaadir Ibn Hassan