What happened
A DC-9 was positioned second in sequence for an ILS approach, following a commuter aircraft. Due to the presence of snow and slush on the runway, aircraft were placed in a holding pattern while chemical treatments were applied to the pavement. During this time, the captain requested a braking action report from the tower controller. Although the controller relayed the request to the preceding commuter aircraft, no braking action report was received before the DC-9 commenced its landing.
The captain proceeded with the approach using full auto-land settings despite the contaminated runway conditions, the lack of a braking action report, and a crosswind component of 13 knots. Upon touchdown, the autopilot attempted to maintain the aircraft on the runway centerline. After approximately 18 seconds, the aircraft's nose began drifting to the left. The captain then disengaged the autopilot and applied full right rudder and braking to counteract the drift.
The aircraft eventually departed the left side of the paved runway at a point approximately 5,500 feet down the 8,998-foot runway, coming to rest facing 80 degrees left of the runway heading. There were no injuries reported.
The investigation
A review of the operator's flight manual was conducted during the investigation. It was determined that the manual contained no specific guidance or operational limitations for pilots regarding the use of full auto-land and roll-out procedures when operating on contaminated runways.