New York CNN  —  US airlines had gone 16 years without a fatal crash until Wednesday night. But as impressive as that safety record had been, there have been warning signs in recent years of a significant risk of a collision like the one that just killed 67 people. A regional jet from Wichita, Kansas, operated as an American Airlines flight by feeder carrier PSA Airlines, was preparing to land at Ronald Reagan Washington National Airport when it collided with a US Army Black Hawk helicopter