I think it’s a great idea and I think a shark is a good start.
However, it’s a bit too aggressive for my taste, so here are two of my ideas. Only in text form though, cause I suck at drawing, but maybe it’ll give you some inspiration:

1) Racing Turtle (no, this is not ment as an insult to Xen ):
Basically a turtle, standing and wearing some old fashioned racing or flight googles and running shoes.
2) Flight Traffic Ferret: A ferret in some kind of uniform (not too much uniform though) and with two of those stick-like flight directing lights (don’t know the proper name, hope you understand what i mean) in its hands.

From the general theme, the second one would be my favorite, but ferrets don’t have many distinguishing features that could be drawn in a style like the Linux penguin or the BSD devil for example. Might depend on the artist though.