Check-in for air travel differs depending on your starting destination, your final destination, the airline you are flying and your travel day and time.
Boys continue growing until age 17 or 18. Boys and girls grow about two inches per year until they reach puberty. Then they each have a growth spurt that lasts a year or two. During the growth spurts, boys grow a little faster than girls. Girls reach puberty (on average) about a year before boys do. Girls also end puberty earlier than boys.
The reason for this is that during a growth spurt a girl only grows about 3 inches a year while a boy grows almost 4 inches. As the teenagers approach puberty, their growth usually stops. Boys tend to reach puberty by the time they turn 17 while girls do the same when they are around 15 to 17 years old.