I'm assuming this question is asked numerous times, but I'm curious. I have a story that involves the sinking a ship on the ocean floor, but with many of the passengers still alive (I won't bog you down with the logistics). The crash will be told from an omniscient narrators POV, examing many areas of the ship and the passengers. However, the later parts are told in 1st person from one of the passengers. Should the initial crash chapter be a prologue? My reasoning is that the POV is radically different and that it's more like background information (although not an infodump, in the true sense of the word).