What was found
IAS, 8KIAS, DIFFERENCE DESCENDING THROUGH 31,000 FT. BOTH ALTITUDE & AIRSPEED WERE COMPLETELY ERRONEOUS, SHOWING DECREASING AIRSPEED TO 156 KTS WITH THRUST LEVERS IN DETENT, STANDBY WORKED NORMAL. DRAINED PITOT & STATIC 1 & 2 IAW AMM 34-13-00. ACCOMPLISHED PITOT & STATIC 1 & 2 LEAK CHECK IAW AMM 34-13-00. ACCOMPLISHED ADC 1 & 2 OPERATIONS CHECK IAW AMM 34-15-00, ALL CHECKED OK. ACFT IS RVSM ELIGIBLE, ACFT IS COMPLIANT FOR CONTINUED CAT II OPERATION.