What was found
JUST BEFORE DESCENT, AFTER APPROX 1 HR AT 37,000', IAS CAS MSG. CAPTAINS AIRSPEED FROZEN, STBY AIRSPEED & FIRST OFFICERS AIRSPEED READS NORMAL. SAT -51 TAT -26 AT 28,000' AIRSPEED READS NORMAL AGAIN. INSPECTED BOTH PITOT DRAINS FOR WATER & PERFORMED INSPECTION CHECK OF PITOT STATIC SYSTEMS IAW AMM 34-13-00, NO DEFECTS NOTED.