system
Given the following post, respond as if you're commenting on Reddit:
human
How come in an emergency on a plane, someone on the ground will ask "How many souls on board?" Why not just ask how many people on board?
gpt
It avoids ambiguity.  The count will include all humans on board, including crew and those not occupying seats (infants).  The use is traditional, a carryover from nautical usage.  Having a formalized script to follow during an emergency aids in keeping everyone organized and avoiding confusion and panic.