What happened
On a scheduled domestic flight originating from Los Angeles International Airport with stops in Cincinnati and Pittsburgh, the aircraft began its descent into the Cincinnati area later than usual due to traffic conflicts. During this descent, the crew maintained a higher rate of descent than standard procedures suggest. While the crew had corrected an incorrect altimeter setting after hearing it broadcast to another aircraft, they were operating under conditions where the ILS glide slope, middle marker, and approach lights were unavailable.
The flight crew planned to descend to a minimum altitude of 1,290 ft AMSL to account for these equipment outages. As the aircraft passed the outer marker at 2056 hours, the landing gear was extended and flaps were set at 40 degrees. Following the marker, the aircraft established a descent rate of 1,800 ft/min. Shortly before impact, the descent rate increased to approximately 3,000 ft/min as the crew requested 50-degree flaps and reduced thrust. The Boeing 727 (implied by context of flight type/procedure) struck tree limbs at an elevation of 875 ft AMSL, approximately 9,357 feet short of the runway threshold. After multiple impacts with trees and the ground, the aircraft came to rest 6,878 feet from the runway and caught fire. The accident resulted in 70 fatalities and 12 serious injuries.
Findings
Investigation into the crash identified that the crew attempted a night, visual approach without a glide slope during worsening weather conditions. A significant contributing factor was the lack of adequate altimeter cross-reference during the approach. Furthermore, the use of visual references to partially illuminated and irregular terrain likely created an illusion regarding the aircraft's actual clearance from the ground.