Narrative:

Approximately 25 minutes out from ZZZ; copied ATIS information. Runway xx mu values reported 40/40/40. Heard ramp mu value of 35; but did not write it down. Knew that was at least 'fair' and we would assess on the ground. During the descent; copied updated ATIS information and updated crew on weather. Landed on runway xx and exited at taxiway D4. Secured the #3 engine after 2 minutes. Ground gave clearance to taxi to ramp via taxiway D1. Control and braking action on taxiway D was good. Approaching taxiway D1 to cross runway xx; ground cautioned that it was 'slick' on the west side of taxiway D1. As we crossed runway 31 and onto ramp; we noted that there were some slick spots; but felt we still had control of the aircraft and proceeded with caution. Reported to ground that the braking action was 'poor' but acceptable. Decided to stay to the left of the taxi line on taxiway east (ramp) to make use of the visible pellets on the ground to enhance braking action; and to provide additional room to make the left turn toward our parking spot. After completing the westbound turn on taxiway east; we began to lose braking effectiveness as the grade of the ramp appeared to visibly decline. The captain asked the first officer to assist on the brakes. The first officer suggested possible use of pneumatic brakes; but it was quickly determined that the problem was not lack of brakes; but sliding. As it became apparent that the aircraft would depart the ramp surface; we secured the engines; and the second officer performed the loss of all power on the ground standard procedure. After the aircraft came to a stop; the captain called for APU start to regain power on the aircraft; and we proceeded to a normal APU power configuration. We stayed on board the aircraft during the tow operation to assist the ground crew. As airport authority responded to the ramp; we noted the vehicles were sliding in the area that the aircraft lost braking action. Also during this time; we heard other aircraft experiencing poor braking action on taxiways near the passenger terminal; and subsequent taxiway closures by ATC. Upon exiting the aircraft once towed to the parking spot; ramp personnel stated that they had problems earlier with vehicles sliding on the ramp. Based on the information provided to the crew via ATIS; reported braking action by ATC; and crew assessment of the initial braking action on the ramp; we expected acceptable braking and control.

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Original NASA ASRS Text

Title: Despite acceptable decelerometer reading on icy surfaces; B727-200 slides off ramp. Ultimately towed to gate.

Narrative: Approximately 25 minutes out from ZZZ; copied ATIS information. Runway XX Mu values reported 40/40/40. Heard ramp Mu value of 35; but did not write it down. Knew that was at least 'fair' and we would assess on the ground. During the descent; copied updated ATIS information and updated crew on weather. Landed on Runway XX and exited at Taxiway D4. Secured the #3 engine after 2 minutes. Ground gave clearance to taxi to ramp via Taxiway D1. Control and braking action on Taxiway D was good. Approaching Taxiway D1 to cross Runway XX; Ground cautioned that it was 'slick' on the west side of Taxiway D1. As we crossed Runway 31 and onto ramp; we noted that there were some slick spots; but felt we still had control of the aircraft and proceeded with caution. Reported to Ground that the braking action was 'poor' but acceptable. Decided to stay to the left of the taxi line on Taxiway E (ramp) to make use of the visible pellets on the ground to enhance braking action; and to provide additional room to make the left turn toward our parking spot. After completing the westbound turn on Taxiway E; we began to lose braking effectiveness as the grade of the ramp appeared to visibly decline. The Captain asked the First Officer to assist on the brakes. The First Officer suggested possible use of pneumatic brakes; but it was quickly determined that the problem was not lack of brakes; but sliding. As it became apparent that the aircraft would depart the ramp surface; we secured the engines; and the Second Officer performed the loss of all power on the ground standard procedure. After the aircraft came to a stop; the Captain called for APU start to regain power on the aircraft; and we proceeded to a normal APU power configuration. We stayed on board the aircraft during the tow operation to assist the ground crew. As Airport Authority responded to the ramp; we noted the vehicles were sliding in the area that the aircraft lost braking action. Also during this time; we heard other aircraft experiencing poor braking action on taxiways near the passenger terminal; and subsequent taxiway closures by ATC. Upon exiting the aircraft once towed to the parking spot; ramp personnel stated that they had problems earlier with vehicles sliding on the ramp. Based on the information provided to the crew via ATIS; reported braking action by ATC; and crew assessment of the initial braking action on the ramp; we expected acceptable braking and control.

Data retrieved from NASA's ASRS site as of April 2012 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.