Narrative:

I departed gso with 5 passenger going to lwb. Ceiling was 300', visibility was 1 mi. Right after entering IMC, pilot's airspeed indicated what I perceived to be an erroneous indication. Then, as climb continued, the airspeed indicator went counterclockwise to 0 and below. Because WX was much better in lbw, I decided to go there to land rather than to return to gso and shoot an approach there with current low WX. No altitude deviations were discovered until several mi north of gso. Then the pilot's altimeter was read at 7800' and the copilot's altimeter at 10,400'. The copilot's altimeter actually indicated 20,400', which was our actual altitude. Cabin altimeter now showed maximum differential and about 3000'. Confusion existed at this time because of so much conflicting information that was seemingly unrelated. I was then cleared for an approach to lwb and I decided to at least start the approach in VMC. Because glide slope indications were unreliable, I abandoned the approach and asked for clearance to roa, my alternate. The roa WX required an instrument approach, so I asked for and received a clearance back to gso. I then asked for and received vectors to another airport in the gso area operating in VMC at 8000' to confirm my altitude as being 8000'. As soon as this was done and I then knew the copilot's altimeter was operating correctly, I asked for and received an approach clearance into gso and landed without further incident. Being distracted by my first symptom (bad pilot's airspeed indication) for much longer than necessary caused me to misread copilot's altimeter and therefore caused me to totally disbelieve all other indications that were correctly displayed. These indications were: good copilot's altimeter, cabin altitude and differential pressure gauge, OAT gauge. The problem turned out to be a large static leak through the pilot's airspeed indicator.

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Original NASA ASRS Text

Title: CPR SMT ACFT EQUIPMENT PROBLEM RESULTS IN PIC NOT BELIEVING EITHER HIS OR THE FO'S INSTRUMENTS. REQUESTED VECTORS TO VFR AREA FOR LNDG.

Narrative: I DEPARTED GSO WITH 5 PAX GOING TO LWB. CEILING WAS 300', VISIBILITY WAS 1 MI. RIGHT AFTER ENTERING IMC, PLT'S AIRSPEED INDICATED WHAT I PERCEIVED TO BE AN ERRONEOUS INDICATION. THEN, AS CLIMB CONTINUED, THE AIRSPEED INDICATOR WENT COUNTERCLOCKWISE TO 0 AND BELOW. BECAUSE WX WAS MUCH BETTER IN LBW, I DECIDED TO GO THERE TO LAND RATHER THAN TO RETURN TO GSO AND SHOOT AN APCH THERE WITH CURRENT LOW WX. NO ALT DEVIATIONS WERE DISCOVERED UNTIL SEVERAL MI N OF GSO. THEN THE PLT'S ALTIMETER WAS READ AT 7800' AND THE COPLT'S ALTIMETER AT 10,400'. THE COPLT'S ALTIMETER ACTUALLY INDICATED 20,400', WHICH WAS OUR ACTUAL ALT. CABIN ALTIMETER NOW SHOWED MAX DIFFERENTIAL AND ABOUT 3000'. CONFUSION EXISTED AT THIS TIME BECAUSE OF SO MUCH CONFLICTING INFO THAT WAS SEEMINGLY UNRELATED. I WAS THEN CLRED FOR AN APCH TO LWB AND I DECIDED TO AT LEAST START THE APCH IN VMC. BECAUSE GLIDE SLOPE INDICATIONS WERE UNRELIABLE, I ABANDONED THE APCH AND ASKED FOR CLRNC TO ROA, MY ALTERNATE. THE ROA WX REQUIRED AN INSTRUMENT APCH, SO I ASKED FOR AND RECEIVED A CLRNC BACK TO GSO. I THEN ASKED FOR AND RECEIVED VECTORS TO ANOTHER ARPT IN THE GSO AREA OPERATING IN VMC AT 8000' TO CONFIRM MY ALT AS BEING 8000'. AS SOON AS THIS WAS DONE AND I THEN KNEW THE COPLT'S ALTIMETER WAS OPERATING CORRECTLY, I ASKED FOR AND RECEIVED AN APCH CLRNC INTO GSO AND LANDED WITHOUT FURTHER INCIDENT. BEING DISTRACTED BY MY FIRST SYMPTOM (BAD PLT'S AIRSPEED INDICATION) FOR MUCH LONGER THAN NECESSARY CAUSED ME TO MISREAD COPLT'S ALTIMETER AND THEREFORE CAUSED ME TO TOTALLY DISBELIEVE ALL OTHER INDICATIONS THAT WERE CORRECTLY DISPLAYED. THESE INDICATIONS WERE: GOOD COPLT'S ALTIMETER, CABIN ALT AND DIFFERENTIAL PRESSURE GAUGE, OAT GAUGE. THE PROBLEM TURNED OUT TO BE A LARGE STATIC LEAK THROUGH THE PLT'S AIRSPEED INDICATOR.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.