Complex sentence: Four passengers survived the crash, all of whom were seated in the same row and in close proximity to the overwing emergency exits, a structurally reinforced part of the aircraft cabin due the wing spars.
Split into simpler sentences: Four passengers survived the crash, all of whom were seated in the same row. The survivors were seated in close proximity to the overwing emergency exits, a structurally reinforced part of the aircraft cabin due the wing spars.