Hi chewytoffee
In most (if not all) instances nowdays, smaller items such as letters
always travel via air mail. This is because the transportation of such items may only cost a little bit more as compared to surface mail (and get to the destination at a much quicker rate).
I wouldn't worry about your requests too much, they should be fine

As Kelly said, someone will probably write "AIR MAIL" on your envelopes on you ... or else they'll most likely travel via air mail regardless.
nowandagain [rockon]