All this talk of raising visors is correct but of course if you had a "full helmet" you had to take it off, this is where we get the idea of raising hats from in the first place. The salute purely being the military version of hat raising. As I have stated earlier the Albert raised hats as well. As to the idea of not wearing uniform, I think you might find that the Geneva Convention has somthing to say about that! Though I do Know an old gentleman (RNVR) who flew a Swordfish from MAC ships with the Title "MERCHANT NAVY" painted on the side of his aircraft. He wore dog robbers under his flying clothing on the grounds that if fished out of the oggin by a german he wpould end up in a better class of prison camp. Of course if he had reached enemy held land he would have been shot!