  The vitality of an edge in a graph with respect to the maximum flow between
two fixed vertices $s$ and $t$ is defined as the reduction of the maximum flow
value caused by the removal of that edge.
  The max-flow vitality problem has already been efficiently solved for
$st$-planar graphs but has remained open for general planar graphs. For the
first time our result provides an optimal solution for general planar graphs
although restricted to the case of unweighted planar graphs.
