According to the timeline I saw they were cleared before declaring an emergency. This means at the time of emergency the standard checklist required their gear had been locked and flaps set. Either they were not operating within regulation before they declared emergency, or they raised gear and retracted flaps below 900 AGL and decided to make an impossible turn instead of stabilizing their flight.

I don't know what happened in this event, but the concrete box is painfully uninteresting compared to basically anything that happened before it.