Approach and Deviation
The flight was cleared for an instrument landing system (ILS) approach. The ceiling was 200 feet overcast, visibility was 1 mile, and runway visual range was greater than 6,000 feet. The first officer was the pilot flying; according to company operating procedures, the minimum ceiling for a first officer flying is normally 500 feet. Air traffic control radar indicated that the aircraft was left of the localizer course and/or below the glide path for the majority of the final approach segment below 1,000 feet above touchdown, deviating from the company's stabilized approach limits.
Breakout and Recovery
The aircraft broke out approximately at minimums (200 feet above touchdown), left of and diverging away from the runway centerline. The captain called out, "push it down, push it down, push it down" and asked, "you got it or you want me to get it?" The first officer replied, "I can get it," and the captain said, "OK." Subsequently, the aircraft pitched down and banked up to approximately 14 degrees while correcting back to the runway. A high sink rate existed in the last few seconds before touchdown; the flight data recorder registered a vertical acceleration of about 1.8 G at touchdown.
Wheel Separation and Damage
The aircraft's number 1 main landing gear wheel separated from the aircraft at or shortly after touchdown. The separated wheel entered the airport ramp area and struck two parked trucks and a baggage cart in front of the main passenger terminal.
Post-Incident Examination
Post-incident examinations of the aircraft's number 1 wheel retaining nut disclosed that the nut threads were worn approximately 0.030 inch beyond engineering drawing specifications.
Regulatory Context
FAA guidance directs FAA principal operations inspectors to ensure their operators' operations manuals contain stabilized approach criteria as well as required actions in the event of deviations ("i.e. missed approach or go/around [sic]"). The company's DC-8 operations manual states only that deviations from the stabilized approach profile "are cause for consideration to abandon the approach."