Flight 227, operated by a Boeing 727-22, departed LaGuardia Airport at 08:35
MST (10:35
EST) for San Francisco, California, with scheduled stops in
Cleveland,
Chicago,
Denver, and
Salt Lake City. The flight to Denver was routine. In Denver, a new
flight crew took control of the plane:
Captain Gale C. Kehmeier,
First Officer Philip E. Spicer, and
Second Officer Ronald R. Christensen. The flight took off from Denver at 16:54 MST, a few minutes after sunset. During the flight, the first officer was flying the aircraft under the direction of the captain. At 17:35, it was cleared to descend to by the Salt Lake City
Air Route Traffic Control Center. At 17:47, now under the direction of
terminal control, the plane was cleared to approach. At 17:48, in response to the controller's request for the plane's altitude, the pilot replied, "Okay, we've slowed to two fifty () and we're at ten (), we have the runway (34L) in sight now, we'll cancel and standby with you for traffic." The plane began to descend, but its rate of descent was approximately per minute, nearly three times the recommended rate of descent. At approximately 17:49:30, the plane passed the
outer marker from the runway threshold at approximately , over above the normal
glideslope. The
elevation of the Salt Lake City airport is above
sea level. At approximately 17:51, one minute prior to impact, the plane passed ; it was still above the normal glideslope, and still descending at per minute. Around this time, the first officer reached forward to advance the
thrust levers to increase thrust, but the captain brushed his hand aside and said, "Not yet." At thirty seconds prior to impact, the plane was above and from the runway. The captain indicated in post-crash interviews that at this point, he moved the thrust levers to the takeoff power position, but the engines failed to respond properly. However, both the testimonies of the other members of the flight crew and the data from the
flight data recorder (FDR) indicate that the attempt to add power occurred only about ten seconds before impact. At 17:52, the plane struck the ground short of the runway, then slid . The separation of the landing gear and the No. 1 engine was the result of impact loading in excess of their design structural strength. The failure of the landing gear caused the rupture of fuel lines in the fuselage. The resulting fire, rather than the impact of the crash, accounted for all 43 fatalities. The incident occurred approximately forty minutes after sunset. The Boeing aircraft had been delivered to United seven months earlier on April 7, 1965, and had less than 1,800 hours of flight time. ==Investigation conclusions==