Investigators examining the black box data from the recently crashed aircraft have discovered a major discrepancy that could offer critical insight into the cause of the tragic collision.Preliminary findings from the investigation into the fatal crash involving an American Airlines CRJ-700 jet and a U.S. Army Black Hawk helicopter near Washington, D.C., which resulted in the loss of 67 lives, point to a significant altitude discrepancy at the time of the incident, according to DailyMail.com.