Incident Overview
A night cargo flight was dispatched from the company's main hub into an area of potentially severe weather, influenced by a stationary front and Tropical Storm Frances. The terminal forecast provided to the flight crew was two days old, and the crew was not properly briefed on the forecasted weather conditions for the destination airport. They were also not provided with all adverse weather information and NOTAMS affecting the route and destination.
Approach and Landing
The flight crew missed the first approach to runway 17R due to strong crosswinds. They were subsequently vectored for a Category I ILS approach to runway 35L. Level 4 to 5 convective activity with tops to 42,000 feet was present over the destination airport at the time of the mishap. The aircraft was configured for an autoland approach with auto-brakes set for maximum braking. A strong crosswind to a quartering tailwind prevailed during final approach and landing.
Runway Conditions
The aircraft touched down 17 feet left of the centerline of the 9,000-foot-long ungrooved concrete runway, which was reported to be partly flooded due to its low crown. The autopilot was never disconnected, and no abort was attempted. The tower had previously reported standing water at the intersection of runway 17R and taxiway Delta during the first approach. The investigation revealed that the runway condition check was conducted by driving a vehicle over the runway centerline for its full length. When another torrential rain shower moved across the airport, the investigation team observed rapid water pooling on the runway, mostly away from the centerline, with a depth measured at least seven inches. The issued "standing water" report failed to indicate the severity of the flooding.
Weather Conditions
Heavy rain showers, sometimes described as torrential, prevailed throughout the area. A weather station 29 miles to the southeast reported 7.64 inches of rain from the tropical storm. Witnesses reported that the airplane produced a heavy rooster tail of water upon touchdown on runway 35L. Airport Rescue and Fire Fighting personnel, whose fire house was approximately one-quarter mile across the ramp from the aircraft's resting place, could not see the aircraft due to the heavy rain, with some first responders describing the rain as "raining sideways."
Aircraft Systems and Tire Marks
Tire marks on the concrete runway, from the touchdown point to where the aircraft exited the left side of the 150-foot-wide runway, were similar to "steam cleaning" and consistent with hydroplaning. Nose wheel steering was operational during the landing sequence. Main tire pressures were within inflation limits (185 to 200 PSI). Two main tires (numbers 3 and 7) were damaged and deflated, with one tire showing bluing (discoloration).
System Examinations
On-board avionics test equipment recorded no faults with the autoland system during the flight. Examination and bench testing of the eight brake assemblies revealed no anomalies. The eight wheel transducers were tested by the manufacturer and found within limits. The anti-skid/auto-brake control unit was also tested and found fully functional.
Flight Data and Navigational Aids
Flight data recorder data, as well as nose wheel tire prints on the runway, indicated that the interconnect between the rudder and nose wheel assembly attempted to steer the aircraft toward the localizer course. All navigational aids associated with the instrument approach were reported as operating normally during both approaches. Sufficient fuel was on board to proceed to the alternate airport.