Originally Posted by
redsnail
I am assuming the pax is appropriately ticketed and documented. That is, they are either on the pax manifest (boarding pass) or the gen dec.
Are they crew of the airline concerned and dead heading to crew the return flight?
The person concerned would be travelling as a passenger with a Standby ticket. However, there seems to be a school of thought that the passenger manifest which is sent to CBP once the flight has departed has to have every passenger assigned a seat number and, therefore, if the passenger had to occupy a cabin jump seat due to lack of a normal passenger seat, that this could cause issues.