A steward or a stewardess.
soda jerk
That is one of the functions of the stewardess or steward
A "Pilot" is a person who drives a plane.
The person who sells drink is known as sellsmen
Pilot.
pilot
passenger
The navigator.
The Pilot.
That person is a 'flight attendant'
A person who serves of his or her own free will is officially called a volunteer.
Someone who serves food is called a "waiter" or a "waitress" and sometimes called "staff".