  A reduced two dimensional model is used to study Ketene isomerization
reaction. In light of recent results by Ulusoy \textit{et al.} [J.\ Phys.\
Chem.\ A {\bf 117}, 7553 (2013)], the present work focuses on the
generalization of the roaming mechanism to the Ketene isomerization reaction by
applying our phase space approach previously used to elucidate the roaming
phenomenon in ion-molecule reactions. Roaming is again found be associated with
the trapping of trajectories in a phase space region between two dividing
surfaces; trajectories are classified as reactive or nonreactive, and are
further naturally classified as direct or non-direct (roaming). The latter
long-lived trajectories are trapped in the region of non-linear mechanical
resonances, which in turn define alternative reaction pathways in phase space.
It is demonstrated that resonances associated with periodic orbits provide a
dynamical explanation of the quantum mechanical resonances found in the
isomerization rate constant calculations by Gezelter and Miller [J.\ Chem.\
Phys.\ {\bf 103}, 7868-7876 (1995)]. Evidence of the trapping of trajectories
by `sticky' resonant periodic orbits is provided by plotting Poincar\'e
surfaces of section, and a gap time analysis is carried out in order to
investigate the statistical assumption inherent in transition state theory for
Ketene isomerization.
