While authorities focus on the cause of the US's deadliest aviation disaster since 2001, families are mourning their loved ones. Here's the latest.

In 1949, a passenger plane and a military craft collided near Washington DC, launching a grim recovery effort in the Potomac River.

A major emergency operation is underway in Washington DC after an American Airlines flight collided in mid-air with a military helicopter. BBC Verify's Nick Eardley has been taking a closer look at what we know so far about the circumstances leading up to the collision.