PA31 PLT DECLARES EMER WHEN HE EXPERIENCED ERRONEOUS PITOT STATIC INDICATIONS BECAUSE PITOT HEAT SWITCHES WERE OFF.

Narrative

I LEVELED ACFT OFF AT 6000 FT AND SET CRUISE PWR. NOTED LOWER THAN NORMAL AIRSPD. CHKED GEAR AND FLAPS AND FOUND THEM TO BE RETRACTED. AIRSPD DROPPED FURTHER (SLOWLY). I ADDED PWR AND CHKED FOR ICE; SUSPECTING PITOT ICE. NOTED OUTSIDE AIR TEMP WAS -2 DEGS C AND ONLY A TRACE OF ICE ON THE WINGS. ON THIS PARTICULAR ACFT; THE ANTI-ICE SWITCHES ARE ON THE L SIDEWALL NEAR THE CAPT'S KNEES; AND ARE HARD TO SEE IN DIM LIGHTING. I LOOKED AND THOUGHT I SAW PITOT HEAT ON. DURING THIS TIME; EVIDENTLY THE ALTIMETER AND VSI FROZE SOMEHOW. ATC CUED ME IN TO THIS AS THEY SAID FIRST I WAS AT APPROX 7800 FT MSL; THEN A FEW MOMENTS LATER; AT 10700 FT MSL. ALTIMETER READ APPROX 5950 FT; VSI INDICATED ZERO FPM; AND AIRSPD INDICATOR READ ZERO. I WAS ABLE TO LEVEL THE ACFT OFF BRIEFLY AND THEN TURNED ON ALL SWITCHES ON THE L SIDEWALL IN THE ROW WITH THE DEICE EQUIP. A FEW MOMENTS LATER; ALL INDICATIONS CAME BACK TO NORMAL. ALT WOUND UP TO 10300 FT MSL; AIRSPD READ 160 KTS; AND VSI APPROX ZERO. I THINK I MIGHT HAVE FAILED TO TURN ON PITOT HEAT IN THE DIM LIGHT AS THE SWITCHES ARE HARD TO READ. THE EMER WAS DECLARED WHEN ATC INDICATED I WAS AT 10700 FT. AFTER EVERYTHING CAME BACK TO LIFE; THE FLT WAS UNEVENTFUL.