I saw this plane at the SeaTac Airport and thought it was very unusual. The wings look too small to even be functional to me. What kind of plane is this and what is it used for?
There is a big clue right underneath the "Sea-Tac Airport" decal - it says
It can be seen a little better on this image
It is a rig used for fire and evacuation training.
A unique tool the department uses is an aircraft mock-up designed for aircraft approach, entry and tactics training on the airfield. The smoke generated is not harmful to the environment and provides a realistic challenge. source: https://www.portseattle.org/page/training
The image below appears to show it in use:
According to this forum post about a Funny Looking SEATAC Plane it's a (fake) firefighter training plane.
On 9/30 taxing north from SEA to ORD there was a funny looking tri-jet plane marked with Seattle Tacoma Airport hanging out by the Alaska Airlines cargo area. Wings folded up. Anyone know anything about this plane or its purpose?
Yeah, it's the firefighter training plane . You hear pilots asking ATC what it is occasionally.
Here's a picture I found on flickr. http://www.flickr.com/photos/smartjunco/331183916/