The downing of Malaysia Airlines Flight 17 in Ukraine on Thursday, following the disappearance of its Flight 370 in March, is the second mysterious incident involving the airline this year. The incidents don’t appear to be related, but that isn’t preventing people from insisting that they’ll never fly Malaysia Airlines again. Some of them will follow through — academic studies have found that high-profile crashes can shift passenger demand away from the airlines involved in the disasters.Is this behavior rational? Should we really be less inclined to fly airlines that have had fatal crashes in the past — even when the crashes don’t appear to be their fault? Or are crashes essentially random events that occur at about the same rate on all airlines over the long run? (The two fatal accidents involving Malaysia Airlines this year were the first for the carrier since 1995.)