An investigation into the January 29 collision between a U.S. Army Black Hawk helicopter and an American passenger jet continues. The NTSB has identified potential missed air traffic control communications and altitude discrepancies from the helicopter crew. This incident marks the deadliest U.S. air crash in nearly 25 years, claiming all 67 lives aboard both aircraft. Investigators are examining the possibility of erroneous data and the role of night-vision goggles used by the helicopter crew during their flight assessment, as well as the oversight of air traffic control operations in the busy airspace.