Changing object dimensions along Y axis - scales Z axis I am a bit confused about axis systems in Blender. In the first figure - the green and blue represent the Y and Z axis. When I translate the object in Y,Z directions it moves perfectly. However, when I change the object dimensions in Z direction it causes the object to change in the Y direction.   

Also, in the first figure the dimensions in (Y,Z) are (725,2809) respectively - but obviously the extent of object in Y is much greater than in the Z direction. This makes me suspect that the dimensions are being shown in a coordinate system different from the one displayed on the screen. Any hints on how do I find it? 

For sake of completeness - the airplane shown in the figure was imported as a .obj file. Since, it was composed a number of smaller meshes - I joined all these meshes into a single object and moved the geometry to origin. This is what is shown in figure 1.
This is because the object is rotated 90&deg; around the X axis.

So blender is scaling the object around the local Z, then rotating the object so that the local Z is aligned with the global Y.

To fix this, apply the rotation with &#9096; CtrlA> Rotation.