Incident Overview
On an ILS approach to runway 35L, the first officer was hand-flying the aircraft. The crew received a special weather observation reporting ceilings of 300 feet and 1,000 feet broken, with 1/2 mile visibility and fog. The approach was briefed for runway 35L. When approach control (TRACON) cleared the aircraft for the approach, it was at 9,000 feet.
Crew Actions and Communications
During the descent, the captain reported that the glide slope indicator "came up and actually went below us," and that the aircraft had not yet intercepted the localizer. The captain requested a lower altitude from TRACON; TRACON apologized and cleared the aircraft to 7,000 feet, asking if the crew would still be able to complete the approach. The crew confirmed they would. The captain stated the aircraft was configured and approaching the glide slope from above while intercepting the localizer, and that the first officer was on the localizer and glide slope.
At 100 feet, the captain called out approach lights in sight, and the first officer acknowledged. When the captain announced reaching the decision altitude, the first officer called for landing. The captain then saw threshold lights and heard the "glide slope" GPWS (Ground Proximity Warning System) warning. The captain called "pull up" to the first officer. Upon touchdown, the captain thought he could see some approach light bars below the nose, but did not feel or hear anything unusual. The landing rollout was normal.
Post-Flight Damage
After parking, the crew discovered damage to the left main brake line and loss of hydraulic fluid from the right system. Additional damage was observed on the left main tires, bottom left aft portion of the fuselage, and the left engine and its cowling.
Runway Examination
Inspection of the runway revealed one approach light, located 19 feet from the beginning of the paved overrun, broken forward at its base. Approximately 49 feet from the start of the paved overrun surface, the beginning of two pairs of parallel tire marks was observed. The left pair of tire marks ran through three sets of center approach lights in the overrun, two runway threshold lights, a distance of 354 feet, and continued down runway 35L for approximately 700 feet. Light stanchions, broken lens pieces, and bulb debris were found extending down the runway along the tire marks.
Flight Data Recorder Information
The FDR showed that the aircraft captured the ILS glide slope 38 seconds prior to touchdown at a radio altitude of 734 feet. FDR pitch data, recorded 4 seconds later, indicated the aircraft was tracking the glide slope at a radio altitude of 617 feet. At 5 seconds prior to touchdown, the glide slope displayed a 2-dot fly-up deviation, and the aircraft was at a radio altitude of 114 feet; the glide slope warning was active. The glide slope deviation increased to 4.3 dots fly-up at touchdown. Airspeed at touchdown was 133.5 knots. Vertical acceleration was 1.7 g followed by 0.7 g approximately 0.5 second later. Lateral acceleration was -0.15 g. The right outboard spoiler began to deploy at touchdown plus 2.5 seconds. The hydraulic pressure low lights (left and right) remained in an "off" state throughout the incident sequence.
Maintenance and Training Background
Examination of the aircraft's avionics equipment and the airport's ILS approach showed no anomalies. Flight crews are administered a simulator check every 9 months, either by the company or the FAA, and crews do not fly practice approaches in the airplane. The first officer's last simulator checkride was 14 months prior to the incident. The first officer stated he could not recall the last time he flew an instrument approach in actual weather conditions.