Personally, I try to resist speaking in a foreign lingo (my english is probably bad enough), so as to avoid the problem of a foreign passenger trying to engage me in conversation in their language, where my quizical look and gallic shrug may subsequently offend. Incidentally, BA flight crews are issued with a book of multilingual versions of "Good morning, this is the Captain etc." in languages as diverse as French, Arabic and Japanese.
[This message has been edited by airforcenone (edited 21 January 2001).]