While God’s plan for your friend’s parents included the fact that they would die in this airline crash, He did not causally predetermine it. His will for their lives was evidently, not that they should die years apart after lingering battles with illness or pain, but that they should be taken together quickly to His side. Their deaths fit into God’s providential plan for human history, which is to establish His Kingdom among men. God has good reasons for permitting them to die in this crash, otherwise He would not have allowed it. But as you know from reading The Only Wise God, God’s sovereign providence over human history does not imply His causally determining everything that happens. This event was the result of an incomprehensible multitude of free human choices which God did not determine. If her parents had decided not to travel on this flight because of a dream, then God’s plan would have taken a different course. His providential planning would have to have taken into account that free choice instead of the choices He did have to work with. God’s providential plan does not override human free choices but rather takes account of them.
That's a strange argument. God cannot prevent a plane crash without overriding our freewill?
Let's grant libertarian freedom for the sake of argument. Let's play along with that assumption. Let's consider some causes of plane crashes:
i) Terrorism would be the most direct example. A passenger smuggles a bomb onboard. A pilot deliberately crashes the plane. A mechanic sabotages the plane. In each case, the agent intends the (dire) outcome. According to the freewill defense, God must respect human choices.
But even on its own grounds, there's a problem with that argument. Take the Air France model of the A1380, which seats 538 passengers. You have one terrorist who wills the plane to crash over against more than 500 passengers and crew who will the opposite. God can't respect everyone's will in the case of conflicting volitions. Why does he side with one terrorist?
ii) A less direct example would be human error (e.g. pilot error, air traffic controller error, a design flaw, faulty maintenance). These involve free choices. However, in this case, the agent doesn't intend the outcome. The plane crash is an unforeseen consequence of human choices If the agent knew in advance the end-result of his action, he'd be appalled. He would avoid that error.
How does it violate human freewill for God to correct a short-sighted or uninformed choice which the agent never intended?
iii) Then there are impersonal causes (e.g. metal fatigue, bird strikes, lightning strikes, downdrafts) that don't involve human choice. Why is God not allowed to override metal fatigue or windshear? He's not overriding the freewill of the weather or machinery, is he?
Sure, Craig can say that if passengers hadn't chosen to board the doomed plane, they would not have died. But if God mustn't override human choices at all, then how can he ever answer prayer? Nearly every answered prayer will intersect with a multitude of human choices at the time or down the line. How can answered prayer be consistent with every human volition that's impacted by answered prayer? Isn't Craig's position Deistic? God flicks the first domino (creation), but after that he can't interrupt the domino effect (i.e. actual human choices). Once he flicks the first domino, his hands are tied thereafter. He just watches them fall.