Generally speaking, no we don't split our family up during trips "to be safe". Nor to "continue a family or lineage". I think that air travel has fewer accidents per thousand people traveling, but that in the cases where there is a serious accident, the percentage of fatalities is probably higher (haven't researched it, but just a guess).
If I were the only one to survive a fatal car accident that took my entire family, I would be horribly torn apart and probably go through all phases of mourning, including survivor's guilt. But I would hope that God would sustain me and help me through it. I don't think my family would want me to live the rest of my days wishing I, too, were dead along with them. But, having never been in that situation, that too is only a guess.
Not really thought of the consequences of the "whole family" dying.... except maybe who would come let our dog out and adopt her? I mean... we'd be gone..so what's to ponder? Right?
ETA: I also think that consideration needs to be made as to what KIND of air travel you are referring to. Private planes seem riskier than commercial airliners. My husband is an air traffic controller and has been for 20 years. He has never worked a plane that crashed. And many of his co-workers can say the exact same thing. Never even a plane in distress. But many small planes fly by visual flight rules below altitude and do not use en route ATC, only the local airport controller--if there is one. Many small airports don't have one, unless I am mistaken. Individuals who are flying their own planes take a lot more risks, in my opinion. Much can go wrong, with very little in the way of alternatives to resolve any given situation. Yes, we read about pilots who have had a few drinks on their layover before reporting for duty for the return leg or some such. But how many private pilots have no one monitoring them at all? By no means am I suggesting that the pilot you are referring to, or others like him, took unnecessary risks. But it is more likely to think "oh, I can manage it" I would think. Look at JFK Jr's fatal flight. There are up and down sides to smaller private planes, like anything else. I just think you have to categorize them separately from commercial flight in the question you pose, personally.