Narrative:

Student and instructor were coming back from the practice area. A discussion about runway conditions; the type of landing; and what would be different (application of brakes; letting the airplane coast more than normal on the contaminated runway; what will happen in the event of slippage/stuck brake) on this particular full stop landing took place in the downwind leg of pattern. The student took the landing with the instructor shadowing on the controls. Approach; flare; and touchdown were stable and controlled. The aircraft maintained a straight roll out path on runway centerline for about 2-3 seconds before the nose slowly drifted to the left. The student applied light braking to the right with little success. Instructor took control and applied rudder deflection and greater brake pressure to the right. The aircraft initially responded by correcting to a straight roll out path; then veered left again and departed the runway regardless of rudder/brake pressure applied to the right. Crew notified tower and performed shutdown. No injuries noted.a thorough weather briefing; indicating runway mu values in the mid-high 20s was obtained prior to launching. ATIS was obtained prior to entering btl airspace. At the time; runway conditions were thin dry snow over ice with mu values in the mid 20s. The mu values below 40 indicated less than ideal braking; but not impossible landing conditions. The crew believed the contaminated runway to be an acceptable risk. A better understanding of braking action reports; aircraft landing performance on; and different landing procedures for contaminated runways could be gathered and applied to conditions such as these to help determine the likelihood of conducting a safe flight.

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Original NASA ASRS Text

Title: A Cirrus pilot and instructor reported a loss of control and runway excursion at BTL due to field conditions.

Narrative: Student and instructor were coming back from the practice area. A discussion about runway conditions; the type of landing; and what would be different (application of brakes; letting the airplane coast more than normal on the contaminated runway; what will happen in the event of slippage/stuck brake) on this particular full stop landing took place in the downwind leg of pattern. The student took the landing with the instructor shadowing on the controls. Approach; flare; and touchdown were stable and controlled. The aircraft maintained a straight roll out path on runway centerline for about 2-3 seconds before the nose slowly drifted to the left. The student applied light braking to the right with little success. Instructor took control and applied rudder deflection and greater brake pressure to the right. The aircraft initially responded by correcting to a straight roll out path; then veered left again and departed the runway regardless of rudder/brake pressure applied to the right. Crew notified Tower and performed shutdown. No injuries noted.A thorough weather briefing; indicating runway MU values in the mid-high 20s was obtained prior to launching. ATIS was obtained prior to entering BTL airspace. At the time; runway conditions were thin dry snow over ice with MU values in the mid 20s. The MU values below 40 indicated less than ideal braking; but not impossible landing conditions. The crew believed the contaminated runway to be an acceptable risk. A better understanding of braking action reports; aircraft landing performance on; and different landing procedures for contaminated runways could be gathered and applied to conditions such as these to help determine the likelihood of conducting a safe flight.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.