On Commercial Air Planes and Landing?

Tweet

Some of my family members went on a summer vacation and while the air plane, they were decreasing in altitude preparing for landing. They said that the plane suddenly increased in altitude again; a rapid increase! The captain then shortly announced that the elevation from level ground was not appropriate for landing and so he had to go around and re-do it. My question is, is this normal or is this a serious mistake?And why would it happen?