Day 7: 9:00 AM - 10:00 AM - S7-E2
Factual error: Tony Almeida takes control of 2 planes to create a near miss. In reality all aircraft use a commonly available AM voice radio and pilots can hear each other's radio communications. It would be straightforward to contact the planes and warn them.
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.