Airplanes as far as you can see...

at the airport on the observation deck I spot airplanes and a flat caterpillar-like 4-wheel vehicle. Awesome, how small it looks next to the airplane.
I find out from a member of the service staff that it is an aircraft tractor: OK, an aircraft tractor...

what if it should pull an aircraft like this one:


this is what an aircraft tractor looks like:
Pushback tractors use a low profile design to fit under the aircraft nose. To have enough traction, the tractor needs to be heavy, and most models can have extra ballast added. A typical tractor for large aircraft weighs up to 54 metric tons and has a drawbar pull of 334 kN Often, the driver's cabin can be raised for increased visibility when reversing, and lowered to fit under aircraft.

»»» http://en.wikipedia.org/wiki/Pushback