En la figura ref{fig:pl} se muestra ...

begin{sidewaysfigure}[h!]

centering

begin{minipage}[c]{.33linewidth}
includegraphics[width=textwidth]{PL-tv.pdf}
label{fig:pl:tv}
subcaption{Velocidad}
end{minipage}

begin{minipage}[c]{.33linewidth}
includegraphics[width=textwidth]{PL-th.pdf}
label{fig:pl:th}
subcaption{Altura}
end{minipage}

begin{minipage}[c]{.33linewidth}
includegraphics[width=textwidth]{PL-xh.pdf}
label{fig:pl:xh}
subcaption{Trayectoria}
end{minipage}

label{fig:pl}
caption{caption1}

end{sidewaysfigure}