What happened
On the scheduled flight from Denver to Salt Lake City, the United Airlines Boeing 737 (Flight 227) was cleared for an ILS approach to runway 34L. During the final stages of the descent, the aircraft's rate of descent increased significantly, reaching over 2,000 feet per minute. This speed of descent was roughly triple the manufacturer's recommended limit for such an approach. While the first officer attempted to increase engine power to correct the glide path, the captain prevented the adjustment. Consequently, the engines were not powered up in time to stabilize the aircraft.
The plane struck the runway 335 feet before reaching the threshold of the runway. Upon impact, the left and right main landing gear assemblies began to separate from the airframe. The intense forces exerted on the right gear assembly caused structural damage that ruptured fuel lines and severed generator leads. As the fuselage scraped along the runway surface, sparks ignited the leaking fuel, leading to a significant fire. The accident resulted in 43 fatalities and 35 injuries, while 13 passengers escaped without harm.
Findings
The investigation determined that the aircraft was descending at an excessive rate during the approach phase. A critical factor was the failure of the pilot in command to implement timely power adjustments to stabilize the descent rate, which led to the short touchdown and subsequent mechanical failure and fire.