The boxes can withstand intense heat for only relatively short periods, and could have been destroyed in the infernos which followed the crashes.

BBC: Cockpit drama of doomed planes

Of the acres managed by the feds, 190 million are at "unnatural risk" and more than 70 million of those are at "extreme risk" of becoming infernos.

FORBES: Fact and Comment

The plot centers on estranged brothers Kurt Russell (a soon-to-be-legendary firefighter) and William Baldwin (an anxious apprentice), who work out their differences in the midst of mysterious arsons and towering infernos.

NEWYORKER: Backdraft