Bag 6 starts the airport terminal.  Like most CITY builds, they are meant for play so it's really only half a building.  It includes one minifigure and the revolving door entrance.  While the entrance is cool looking, it's about twice the height of a minifigure and there isn't enough physical space for one actually to fit through the door.  I'm not a fan of the design.
This set is designed for children aged 6+, and one of the ways that it is suitable for them is the inclusion of separate instruction booklets and numbered bags for the different parts of the set (see my post about LEGO age range suitability here).  A younger modeller can build the plane or other item of their choice as soon as they open the box. It's not so much one big set as 5 different parts which make a whole scene. My 7 year old son chose to build a jet first of all...
This detailed model features a classic red, black and grey colour scheme, large driver's cab with detailed dashboard, wing mirrors, opening tool storage compartment, 4-cylinder engine with moving pistons, twin-axle steering, double rear axle and chunky tires. Activate the boom to position the water cannon and extinguish the flames! This Power Functions upgradable model can be rebuilt to create an awesome Fire Rescue Vehicle!
The remainder of the build is the control tower and terminal building. First there is a metal detector screener leading to the waiting/secure area of the airport, which seems taller than it needs to be for the minifigures. I think the same effect could have been made with half the height, except that would not allow for an impressive height for the overall tower. However it does seem to be similar to many modern airports with the high ceilings. This area also seems to be someplace to check luggage as evidenced by the rather nifty conveyor belt that comes in a full part. The moving parts of the set include a revolving door (a very tall one, for the first floor) that leads from the secure area of the airport out to the tarmac, and of course the conveyor belt.