Investigators have said the helicopter crew was wearing night-vision goggles that would have limited their peripheral vision. PHOTOS: What we know about the deadly air crash between a passenger ...

Investigators previously said the helicopter may have had inaccurate altitude readings in the moments before the crash, and the crew may not have heard key instructions from air traffic controllers.

Cockpit conversations a few minutes before the crash indicate that the crew may not have had accurate altitude readings, with the helicopter’s pilot calling out that they were at 300 feet (91 ...