he completed the X-15's first powered flight with the XLR-99 engine. Two flights later, on December 6, he brought North American's demonstration program to a successful conclusion as he completed his final flight in the X-15. Although it had been his hope to eventually pilot one of the craft into space, the USAF would not allow it, and gave strict orders which basically amounted to "stay in the sky, stay out of space." Altogether, he completed 16 captive flights (mated to the B-52 launch aircraft), one glide flight and 13 powered flights in the X-15. The retirement of the X-15 (due to funding cutbacks) after its record-setting Mach 6.70 (4,520 mph) flight prompted pilot Pete Knight to remark that he would have pushed it to even faster speeds if he knew it was the last flight. In his remarks to a number of aviation groups, Crossfield cited the X-15 as one of few aircraft that caused grown men to cry upon its retirement. He remained at North American as systems director of test and quality assurance in the company's Space and Information Systems Division where he oversaw quality, reliability engineering and systems test activities for such programs as the Apollo command and service modules and the Saturn S-II booster. In 1966, he became the division's technical director for research engineering and test. Civilian career In 1961, Crossfield became division director of test and quality assurance for NAA's Paraglider project. In 1967, Crossfield joined Eastern Air Lines where he served as a division vice president for research and development and, subsequently, as a staff vice president working with U.S. military and civilian agencies on air traffic control technologies. In 1974–1975, he worked for Hawker Siddeley as a senior vice president supporting HS146 activities in the United States. In 1977, he joined the United States House of Representatives Committee on Science and Technology where he served, until his retirement in 1993, as a technical adviser on all aspects of civil aviation research and development and became one of the nation's leading advocates for a reinvigorated research airplane program. In 1986, this House Committee tasked Crossfield to be a member of the task group assigned to investigate the Space Shuttle Challenger disaster. In a 2000 public lecture, Crossfield described how the X-15 aeronautical calculations and design required computing power that filled four 10'x12' rooms. He went on to say that these very same