How do fat people fly in an airplane?

the same as everybody else.

They book two seats with extra large seat belts....

In 1 1/2 seats.

The same way skinny people do, They flap their arms. MOST do not fly very well.

Are you trying to say fat people need some special thing in order to walk on to a plane.

Most use their feet and legs like skinny passengers.

Booking a seat is similar to how a tall skinny person does it.

Are you thinking fat people need some special Aircraft engine or trained pilot for the plane to depart?

As the average plane is well over 100,000 pounds the specific weight of each passenger does not matter that much.. In a small plane it does and is taken into account by the pilot in their calculations for fuel needs.

If you are large and need the space of two seats then you use two seats. Airline can charge for the extra seat space needed.

I doubt you would want rows and seats made smaller so that us tiny people can travel at a lower cost, Us small ones can fit in the large seat if all the small ones are booked.

Skinny people may not need the entire seat may not need as much fuel to haul their body.

If the public wants Airlines can easily set up large scales and charge each passenger individually on the amount of luggage and individual passenger weight for a price per pound.

Of course when returning home after the Thanksgiving feast expect to pay a premium price for having that extra desert before returning home.

If you want all those FREE things your parents used to get when flying then just pay the same prices adjusted for inflation they did.The seat was expensive the rest was FREE.

The same way your mother does.

Some airline seats are configured with a removable armrest, so a obese passenger can sit across two seats; using a special seat-belt extender.

same way you do nitwit

First class, because coach seats are too narrow

If you can fit in a seat with the arm rests down, you are fine. If you must raise the arm rests to fit and so spill into the next seat you are supposed to pay for two seats but many airlines don't enforce it. As a consequence if the flight is full, whoever is allocated a seat next to a fat person gets half a seat. One man was forced to stand for seven hours on a flight from Anchorage to Philadelphia because his seat was occupied by the fat man in the adjacent seat.

It depends on their size, the seat size, and the airline.