Day 7: 1:00 PM - 2:00 PM - S7-E6
Factual error: Mid-air collisions are almost always prevented by Airborne Collision Avoidance Systems which have been incorporated in all commercial aircraft since at least 1973. These systems are independent of ground control. These planes would not have collided.
Chosen answer: Nobody knew, not even the writers, until at least halfway through the season when they were writing the end. They wanted to keep all options open.
Nick N.