What happened
The flight crew's initial approach briefing was based on an ATIS report suggesting a CAT III ILS approach to runway 16R. However, subsequent descent instructions and a revised ATIS indicated the descent profile was for landings to the north. The captain briefed the first officer for a second time, this time for a CAT III approach to runway 34R. Due to improved RVR, the crew decided to execute a Category I approach.
The captain reported acquiring the approach lights 100 feet above minimums and seeing the threshold and runway at minimums. After disconnecting the autopilot, the captain began the flare; during this maneuver, the first officer noted an increasing sink rate. The captain attempted to increase pitch, and the aircraft touched down with a firm but not hard impact, followed by a normal rollout.
Upon arrival at the gate, the captain notified the control tower that the aircraft may have touched down short of the runway. An airport operations vehicle confirmed observing the MD-90 land prior to the runway numbers, though not in the overrun area.
The investigation
An inspection of runway 34R revealed debris on the pavement. The investigation determined the airplane struck the approach lights approximately 400 feet short of the runway threshold. The impact knocked off two threshold lights and one light each from the 100-foot and 200-foot approach light bars.
The aircraft sustained damage to the left main wheel splash guard and a cut tire. Additionally, a one-inch square piece of metal was found lodged in the left engine noise suppression material, and the left engine's first stage fan section showed damage.
At the time of the incident, weather conditions included freezing fog with visibility less than 1/4-mile, an indefinite ceiling of 100 feet, and winds from 330 degrees at 5 knots.