Pan-Pan is derived from the French word "panne", which means failure or breakdown. Pan-Pan most often refers to a mechanical failure or breakdown of some kind. It is commonly misused as the "mayday" call from an aircraft in distress and is widely accepted as the three-letter acronym, "Possible Assistance Needed." It has been and still is used on aeronautical radios to serve as a means of stating a possible emergency in the future. Believe it or not, there is a hierarchy of words to say in order to inform air-traffic control of dangerous situations while in flight. If there were a very minute possibility of danger during flight, a pilot would notify air-traffic control by saying the word "emergency" three times. Pan-Pan is used when there is imminent danger such as low fuel, the possibility of a fire, or other emergencies that have not yet arisen but will in the near future. Finally, if there is danger present on board like hijackers, fires, engines out, or other emergencies that require immediate assistance, the pilot should say "Mayday" three times.
Due to the confusion of the meaning of Pan-Pan, accidents have occurred over the years. Aircraft accidents, such as Swissair Flight 111 dealing with an electrical fire and Avianca Flight 52 dealing with a fuel emergency, used "Pan-Pan" instead of the term "Mayday" to denote an already existing emergency. However, the term Pan-Pan can be used in an emergency if the correct phraseology is said; "Pan-Pan, Pan-Pan, Pan-Pan," then saying either the station, "Station, Station, Station," or the particular station, "Oceanic Station, Oceanic Station, Oceanic Station," three times afterwards.
After making the appropriate callouts over the frequency, the pilot should then notify air-traffic control or any listeners of the following information: the vessel’s name and description, the number of people on board, the location, the nature of the emergency, and what type of help is requested. Since Pan-Pan is used in the event of an emergency possibly occurring, sufficient time should be available for the pilot to announce all the information.