"at a lower altitude, and with the door being disarmed as it was" The second of these two clauses refers to what actually happened; the first is counterfactual

"at a lower altitude, and with the door being disarmed as it was" The second of these two clauses refers to what actually happened; the first is counterfactual. But since they didn't put the facts about altitude in TFA the impression is that both are true.