Qantas has revealed plans for the world’s longest-duration commercial flight by the end of 2025, ferrying passengers between Sydney and London on Airbus A350s in just over 19 hours. Only a handful of airlines fly non-stop over such vast distances, which present a host of challenges including the capability of planes, commercial viability, and even the health of crew and passengers. Here are some of the longest-duration flights in the world today: Singapore to New York: 18 hrs 40 min Singapore Airlines Flight SQ24 to New York’s John F. Kennedy International airport is currently the longest comm…