So. Inevitably after a plane crash a discussion comes up where someone may say that they're worried about flying now, and someone else pulls out the statistic that driving to the airport is more dangerous than flying. I think this reasoning is basically correct on the long-term, but not appropriate in the short-term.
Suppose it's the day after flight MH370 mysteriously disappeared. Information is extremely sketchy. You're about to get on a similar plane, operated by the same airliner, taking off from the same airport flying the same route. Should you get on the plane? That is, are you wrong to worry more than usual when we have no idea what happened to MH370? I would say no. The complete disappearance of flight MH370 without warning and without a trace the day before says **update your priors** at least for the short-term.
I'd say that a single event like that should not affect your priors much, not enough to reconsider your travel plans. Just like you don't reconsider your driving plans after hearing about yet another car accident on the radio (unless its aftermath directly impedes your trip). However, if you learn about two or more accidents in close succession, this should give you a pause, since it challenges the model of random uncorrelated events.
Not by much, though, since there's Poisson clumping (do planes crash 2 at a time?).
That's the problem with OP: yes, in some strict sense, there will be an epsilon increase after a plane disappearing. But is this increase remotely relevant to any decision? I strongly suspect that if one attempted to formalize it, the contribution of one MH370 incident out of a century of aviation is so small it's overriden by small details of the prior or model or approximations.