I'm studying the transfer function of an aircraft that relates the pitch angle, $\theta$, with the horizontal stabilizer angle, $\delta$. $$ H(s) = \dfrac{\theta (s)}{\delta (s)}$$
I have computed the frequency response by using Matlab, and I plotted the Bode Diagram: amplitude plot and phase plot.
I understand what is the amplitude curve indicating and I'm able to comment the result obtained. But when it comes to studying the phase curve (second figure above) I don't know what is the meaning and how it is related with the other curve.
So, my question is: what can I say from the phase plot by looking at the Bode Diagram of the studied transfer function, $H(s)$?