The Wall Street Journal examined flight route and elevation data to show the moments before American Airlines Flight 5342 fatally collided with ​an Army Black Hawk helicopter.

But even before the National Transportation Safety Board completes its investigation—a neurotically thorough process that will probably take about a year, and thus meshes poorly with the news cycle and the conspiracy-theorist cycle—it is easy to see some of the lines of inquiry that crash detectives will pursue.

The F.A.A. restricted helicopter routes nearby in the aftermath of the Wednesday collision. For some officials, the concerns about clogged airspace were a long time coming.