In aviation, the term "souls on board" is used to refer to every single living person on an aircraft, including passengers, pilots, flight attendants, and even lap infants. This terminology is a direct holdover from ancient maritime tradition, where sea captains used the phrase to account for every human life entrusted to a vessel, distinguishing them from cargo or livestock. In modern air traffic control and emergency response, saying "souls" provides absolute clarity; unlike the word "passengers," which typically refers only to ticketed travelers, "souls" ensures that emergency crews know exactly how many lives need to be accounted for in a rescue operation. It is a precise, inclusive term that cuts through technical jargon to reinforce the human weight of the responsibility held by the crew and controllers during a flight.