What was found
MCI - FLT 819 - AIR RETURN NO EMERGENCY DECLARED LANDING UNEVENTFUL. BOTH AIRSPEED INDS HAD FALSE INDICATIONS ON CLIMB-OUT, F/O HIGH, CAPT'S LOW, CAPTS AIRSPEED THEN WENT OT ZERO AND STAYED THERE. CAPT'S LOW, CAPT'S AIRSPEED THEN WENT OT ZERO AND SYATED THERE. CAPTAINS VSI UNRELIABLE IN FLIGHT. SHOWED 500 FT DESCENT IN LEVEL FLIGHT. READ 0 FPM ON FINAL APPROACH. F/O'S VSI SEEMED OK. REPLACED NR 1 CADC PER MM 34-12-11. OPS CHECK AND LEAK CHECK NORMAL. (M)