What was found
AT FL 370 IN ICING CONDITIONS, RECEIVED A IAS FLAG. HAD AUTOPILOTS DISCONNECT CAPTAINS & FOS AIRSPEEDS SPLIT SIGNIFICANTLY. DECIDED TO DESCEND IN VFR CONDITIONS WHILE RUNNING AIRSPEED UNRELIABLE CHECKLIST. WHILE RUNNING CHECKLIST, CAPTAIN LOOKED LIKE IT WAS THE ONE THAT WAS FAULTY. BEFORE FINISHING CHECKLIST, AIRSPEEDS THEN ALIGNED & OPS NORMAL. COMPLETION OF CHECKLIST HAD AIRPLANE SWITCHED & INDICATIONS BACK TO NORMAL FLT EMERGENCY WAS DECLARED. INSPECTED PITOT TUBES IAW MM 34-11-01-6, ALL FOUND CLEAR. BLOWED PITOT LINES, ALSO CHECKED FOR HEATING. ALL OK. FOUND MSC FAULTING FOR THE 9 PREVIOUS LEGS, R &R MSC IAW MM 31-42-00-0, NO FAULTS FOR MSC. PITOT HEAT NORMAL.