Investigators have recovered the black boxes from both aircraft involved in the deadly midair collision near Washington, D.C., and are working to determine the cause.

Airline pilots flying into Washington, D.C., have reported nearly a dozen near misses that were scarily similar to this week’s midair collision that killed 67 people.

Less snow generally means less salt, but there’s more to it than that. Melting and refreezing also necessitate treatment, and that Arctic blast played a part too.