text: what  is the altitude that  a plane fly?   of course it depends on the type of plane and its capabilities.  but, i suggest you check the faa web site.   i am sure there is leeway, but generally i think altitudes are prescribed depending on the direction you are going.  for ex, planes going in one direction fly at even altitudes, while planes in the opposite direction fly at odd altitudes.  then, i think the airlines have some say depending on wind conditions and weather at those altitudes.  my recent flights were like 37 or 39 thousand feet.  but i was shocked on the flight from houston to honolulu 32 or 33 thousand.  good luck.