Change voting system from FPTP to Runoff (AV or Alternative Vote) to eliminate the Spoiler Effect

We need to change our voting system from First Pass The Post (FPTP) to Alternative Vote (AV, or Runoff). The FPTP system has The Spoiler Effect, which makes it so people can't vote for a smaller party and having there vote count, so people HAVE to vote for a big party (even though they might not like them.) In the AV system, you vote for candidates with numbers of most favorite to least favorite, and if the first vote is at the least, the second vote is counted instead of the first, and so on until one candidate has greater that 50% of the vote, then he/she wins. This eliminates the spoiler effect by allowing people to vote for who they want without the risk of their vote not mattering in the final polls.