If you hear a certain sound when onboard a plane, it could mean that someone has died. Travel experts at Wander have put together a list of in-flight codes and phrases that passengers may encounter on a flight, but not know what they mean. Whilst most flights go smoothly, on others there can be some issues where flight crews need to communicate with each other secretly, so as not to alert passengers. One such code to listen our for is 'Code 300' or 'Angel', which signals that there is a