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...

Primary concept and development work takes place at the Billund headquarters, where the company employs approximately 120 designers. The company also has smaller design offices in the UK, Spain, Germany, and Japan which are tasked with developing products aimed specifically at these markets. The average development period for a new product is around twelve months, split into three stages. The first stage is to identify market trends and developments, including contact by the designers directly with the market; some are stationed in toy shops close to holidays, while others interview children. The second stage is the design and development of the product based upon the results of the first stage. As of September 2008 the design teams use 3D modelling software to generate CAD drawings from initial design sketches. The designs are then prototyped using an in-house stereolithography machine. These prototypes are presented to the entire project team for comment and for testing by parents and children during the "validation" process. Designs may then be altered in accordance with the results from the focus groups. Virtual models of completed Lego products are built concurrently with the writing of the user instructions. Completed CAD models are also used in the wider organisation, for marketing and packaging.[33]
The two stunt jets included here actually have some similarity in the basic design and colour scheme to the main piece seen in the Marvel Super Heroes Avenjet Space Mission set. With that being said, I loved the Avenjet in that particular set, so any similarity holds no issue with me. The red and white colours work really well together, and it looks like something you would genuinely see flying through the sky at an air show. I really love it when LEGO truly capture the essence of what you are building, and they do that here. The jets themselves, as I said before, are similar to previously-released jets, and therefore the builds won’t come as any main surprise. That shouldn’t detract from the product, however, as it is a prime example of LEGO finding a winning formula and not really needing to change it.
The body of the plane is built with five seats for passengers. The wings are added next with what I think are filler stickers added to the top of the wings. There is a small galley with sink and oven in the front of the plane right behind the cockpit. The cockpit uses only one sticker to show navigation equipment - the other is printed, which is always welcome (though not a new piece). A lavatory is installed in the back, and then the inside is complete. There is an odd choice for the door to the lav - a swinging door. Not much opportunity for privacy!
My six year old grandson loves Lego's. His daddy is a pilot so we got him this Lego City Airport for his birthday. Wow! He couldn't wait to put it together! It was organized in bags (which I didn't know) and this prevents overwhelming a little person. At least that's what my son said! He did indeed help our grandson put it together, but that was expected as a father/son project. It is so realistic! I love the tower especially. It has moving parts and all kinds of nifty little things - like luggage! The plane has a bathroom too! This is a great addition to anyone who loves Lego's!
Bag 4 finishes the fuselage and all that is left are the engines and tail section.  You'll notice that this aircraft has a bathroom on board as well as some storage for a non-existent flight attendant.  I think this is the first time that LEGO has put some additional details into aircraft besides just seats.  Also there is only one pilot for a 2 seat cockpit in the set.  
Billund Airport had its beginning in 1961 when the son of the founder of the Lego Group, Godtfred Kirk Christiansen, established a private 800-meter long runway and hangar north of his factory in Billund. With Christiansen as a key driver, more of the neighbouring municipalities were included in the group of owners, and it was planned that the airport should be expanded to a regular public airport.
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