What happened
The aircraft was cleared for an instrument landing system (ILS) approach under weather conditions featuring a 200-foot overcast ceiling and 1 mile visibility. At the time of the approach, the first officer was acting as the pilot flying; however, company operating procedures typically require a minimum ceiling of 500 feet for the first officer to fly.
Air traffic control radar indicated that for much of the final approach segment below 1,000 feet, the DC-8 was left of the localizer course and/or below the glide path, placing it outside the company's stabilized approach limits. The aircraft broke out of the clouds at approximately 200 feet above touchdown, positioned left of and diverging from the runway centerline.
During the correction, the captain instructed the crew to "push it down" and asked if the first officer could correct the deviation. After the first officer confirmed they could handle it, the aircraft pitched down and banked approximately 14 degrees to return to the runway. A high sink rate occurred in the final seconds before touchdown, with the flight data recorder noting a vertical acceleration of about 1.8 G at impact.
Upon or shortly after touchdown, the number 1 main landing gear wheel separated from the aircraft. The detached wheel traveled into the airport ramp area, where it struck two parked trucks and a baggage cart located in front of the main passenger terminal.
The investigation
Post-incident examination of the number 1 wheel retaining nut revealed that the threads were worn approximately 0.030 inch beyond the limits specified in the engineering drawings.