It is the second of three days of witness testimony and public inquiry by the National Transportation Safety Board into the January midair crash over the Potomac River.

The National Transportation Safety Board will wrap up its public testimony on Friday about the fatal midair crash between an Army helicopter and a commercial jet earlier this year

Incorrect altitude readings on the Army helicopter that collided with a passenger plane over Washington, D.C., in January contributed to the aircraft getting too close, but air traffic controllers warned about the hazards helicopter traffic presented years before the crash.

Investigators so far have highlighted several factors that may have contributed to the collision, which left 67 people dead.