In Washington, the NTSB is in the middle of a three-day investigative hearing into last January's midair crash between an Army helicopter and an American Airlines regional jet. Investigators revealed the chopper pilots may not have known they were flying too high because a critical piece of equipment was malfunctioning. NBC News' Tom Costello reports. For more context and news coverage of the most important stories of our day, click here: nbcnews.com » Subscribe to NBC News: nbcnews.to/SubscribeToNBC » Watch more NBC video: bit.ly/MoreNBCNews NBC News Digital is a collection of innovative and powerful news brands that deliver compelling, diverse and engaging news stories. NBC News Digital features NBCNews.com, MSNBC.com, TODAY.com, Nightly News, Meet the Press, Dateline, and the existing apps and digital extensions of these respective properties. We deliver the best in breaking news, live video coverage, original journalism and segments from your favorite ...