Planes and routing - who decides?

I have always taken an interest in the whereabouts of the different aircraft in the fleet and have always wondered who decides on which one is going where? What criteria do they use? Really interested to know if some lovely bod can enlighten me please!

[preiffer]

Hi laluna,

As you've posted the same question elsewhere, I'll lock this one to prevent duplicate conversations happening on the same topic.

Please only post one topic for each subject - someone WILL respond to you in good time, wherever it is posted.