A United Airlines Boeing 727 crashed into Lake Michigan on its approach to O'Hare International Airport on August 16, 1965. The plane was the first Boeing 727 to ever crash. In the following two months two more like it came down near Cincinnati and in Salt Lake City. Yet the Federal Aviation Administration decided not to ground the 727s. 30 people were killed on board the UAL jet which was not even one third full when it crashed. Many pilots who were accustomed to flying DC-6s and other propeller planes were slow to adjust to the rapid descent rates of the Boeing 727s. This may have been a factor in the plane continuing to descend further than the 6,000 feet that it was supposed to level out at prior to landing.