Lego pieces of all varieties constitute a universal system. Despite variation in the design and the purposes of individual pieces over the years, each piece remains compatible in some way with existing pieces. Lego bricks from 1958 still interlock with those made in the current time, and Lego sets for young children are compatible with those made for teenagers. Six bricks of 2 × 4 studs[28] can be combined in 915,103,765 ways.[29]

Thanks for the great review and comparison. I've thought about getting the Friends Airport for my daughter, as we both like the amount of detail inside the plane. Why would Lego think that boys don't care as much about detail? I love the wider body planes, but it's a shame they're not producing the runway plates, or including them in the airport sets, anymore. I agree with ZeeBricks that if they're not going to include everything an airport needs (although as expensive as price/piece these sets are getting it would cost a fortune) they should sell smaller sets that can be added together. Now that I'm feeling nostalgic for classic airport I might rebuild my 6392 and dust off my 6396 and set them up tonight, it's time for some serious swooshing :)
This is a good set if you want an airport. The set includes a big plain and a terminal. The terminal has a control tower, check-in, luggage handler, fuel tank, ... I expanded my terminal and built it on a 32x32 baseplate and used the 2 grey 16x16 plates for the roof. The backside is not completely closed. Otherwise is the luggage belt is not accessible with my hand. I added 2 extra seats in the plane. Normally you have 6 seats in the plane, but I raised it to 8. I wanted more than 8 but that is almost not possible. The plane is brought with a big brick which includes the middle of the plane and the 2 wings and that one limits the possibilities. The toilet in the plane is still on the backside.
Pack your bags and get ready to go on vacation! Head to the airport and check in at the terminal. Put your luggage on the conveyor belt and watch it get loaded onto the passenger airplane. Go through security and then head out the revolving doors to the loading area. Climb the stairs and get buckled in, your trip is about to start! This creative play building toy includes 6 minifigures.
LEGO CITY has some recurring themes that can get old after a while and obviously are meant for younger LEGO fans.  The Fire and Police themes within CITY quickly come to mind as it seems like they have a new run each year.  The Airport theme is one of those that doesn't quite occur every year.  The last airport set was released in 2010 and was set #3182.  This year (2016) another airport was released.  #60104, Airport Passenger Terminal, was released on 1 August 2016 in the US.  It costs $99.99 in the US and contains 694 pieces or $0.144 per piece.  I picked the set up from Amazon at 20% off or $80 ($0.115 per piece).  Yay sales!  Onto the review...
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!
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.
Agent 13 has a pretty plain appearance, with caramel-coloured wavy hair, and a black, spy-like top. Her torso has some nice details, with sharp, angular lines that all combine to form a rough outline of an upside down star. She has plain sand blue pants and rocks a sub-machine gun accessory. I like regular LEGO firearms, so it’s very nice to get one in this set as they’re fairly uncommon.
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