B737 CREW HAD RWY EXCURSION ON ICY AND SNOW COVERED RWY.

Narrative

PERFORMED RECEIVING CHKLIST. PUSHED BACK XA56Z. DEICE BEGAN XB04Z. DEICED ACFT FOR 28 MINS. PERFORMED ENG START; AFTER START; AND TAXI CHKLISTS. ENG ANTI-ICE ON FOR TAXI. CLRED FOR TKOF WHEN TAXIING ONTO RWY 17L. ONLY 50 FT OF RWY CLRED OF SNOW. RWY CONDITIONS: PATCHY SNOW OVER ICE. EACH 50 FT SIDE OF RWY COVERED WITH SNOW. BRAKING RPTS GOOD BY GND CTL ON TAXI OUT. STOPPED ACFT ON CTRLINE. ADVANCED THROTTLE TO 38%. PWR EVEN ON BOTH ENGS. ACFT STARTED SKIDDING TO THE R OF CTRLINE. BROUGHT THROTTLES TO IDLE AND APPLIED FULL BRAKES AND L RUDDER. ACFT SLOWLY SKIDDED TO A STOP WITH R MAIN AND NOSE GEAR OFF THE SIDE OF THE RWY. STOPPED SHORT OF TXWY E2 (APPROX 1000 FT). AIRSPD NOT REGISTERED ON AIRSPD INDICATOR; APPROX 15 KTS. MADE A PA TO REMAIN SEATED. CALLED TWR THAT WE WERE OFF THE SIDE OF THE RWY. CALLED COMPANY. STARTED APU. DID AFTER LNDG CHKLIST. SHUT DOWN BOTH ENGS. COMPANY AND CITY WANTED MAINT INSPECTION BEFORE MOVING ACFT. PAX DEPLANED AND TAKEN BY BUS TO TERMINAL. ALL 5 CREW MEMBERS AND SEVERAL NON REVENUES GOT ON THE LAST BUS AT CD30 LCL. OPS REQUESTED WE DO A TERMINATION CHKLIST AND SHUT DOWN THE APU BUT LEAVE THE BATTERY ON. ALSO REQUESTED MAINT WRITE-UP AND LOGBOOK BE LEFT IN AIRPLANE. NO ACFT DAMAGE; NO INJURIES. ATIS XA55Z 100 DEGS 6 DME. 2 1/2 SCATTERED TO BROKEN; 13 MI OVCST; 18 MI OVCST; - 14/-15; ALTIMETER 29.98. COS ATIS SHOULD HAVE MENTIONED ONLY CTR 50 FT PLOWED. RWY SHOULD HAVE BEEN SANDED.