So I was thinking if you make something that big on the ground, how do you know you've got it right? Do you think someone drew it on a piece of A4, blew it up on a photocopier until it was that big, then laid it on the ground as a template & trampled down the snow / drove a tractor around until they had that "design"
Seriously, this design isn't really that big. At least, "big" in comparison to, say, your average crop circle or something. After all, that runway is, what, 10-15 meters wide? I bet you can simply stand beside it and get a very good feel on whether the proportions are right or not.
Plus, it wasn't done all that neatly. I hate to be known here as a pervert who looks at dirty pictures all day, but look at the right side of the drawing. It would have been very easy to improve on that a bit if they only drew one curve a little differently. Of course, if you remove snow to create a picture, it's pretty hard to undo a mistake. You can shovel snow to cover up your mistake but you will still get a different texture.
What I know about crop circles and similar large scale designs, is that they're highly geometrical in design. You start off by putting a marker pole in the ground somewhere, then use measuring tape to find the location for other marker poles, and use a piece of string to create circles around the marker poles. It requires a few people, if only to hold the measuring tape in place, and a detailed design/plan, but it's basic math, really. Trying to do a Mona Lisa in a crop field would be much, much harder.
So my guess is that this was just a spur-of-the-moment prank, with no real preparation, no serious equipment or a well thought out plan. And it worked, apparently.
