What happened
On the morning of the accident, an aircraft departed San Bernardino County Airport (CNO) in Chino, California, bound for Friedman Memorial Airport in Idaho. The flight was operating under instrument flight rules. Radar and air traffic control records indicate the aircraft departed CNO at approximately 0858 and was initially cleared to climb to 29,000 feet MSL.
During the climb, while passing through 26,000 feet, the first officer requested to return to the departure airport. Although the controller inquired if an emergency should be declared, the first officer initially declined. The crew was instructed to maintain 24,000 feet, and the aircraft began a controlled descent to that altitude. However, shortly after this instruction, the aircraft began a rapid descent. By 0911:24, the aircraft was descending at approximately 10,000 feet per minute, at which point the first officer officially declared an emergency. Following this transmission, all communication and radar tracking were lost.
The aircraft subsequently impacted high desert terrain approximately 3 miles southeast of Helendale. The impact resulted in two fatalities, involving both the captain and the first officer, and the total destruction of the aircraft. An eyewitness observed the aircraft flying below an overcast layer before it pitched nose-down and descended straight into the ground. The witness noted that the aircraft appeared intact during its final descent and did not observe smoke or fire prior to the impact, which caused a large explosion.
Findings
Radar data revealed that the aircraft experienced a rapid, uncontrolled descent at rates reaching 10,000 feet per minute prior to impacting the terrain.