Narrative:

Prior to conducting the VFR flight a thorough preflight check was conducted and no discrepancies were noted. The altimeter setting was compared to the field elevation and the altimeter was noted to be approximately 20 ft low but was determined to be within acceptable limits. During takeoff and climb; the airspeed indicator; vertical speed indicator (vsi) and altimeter all appeared to be indicating correctly; although the vsi and altimeter seemed a bit sluggish during the climb. After contacting departure; I noticed that the altimeter froze at 1;500 ft; even though the airplane was still clearly climbing. ATC asked to confirm altitude; which I reported as 1;500 ft. I noted that the backup GPS altimeter was indicating 2;500 ft; and I reported the discrepancy to ATC accordingly. ATC requested me to recycle altitude squawk reporting but the issue persisted. ATC finally requested that I stop squawking mode C altitude reporting. At this point I was about 20 miles from [the destination airport]; so I elected to land as planned; and used the GPS altitude as backup. I completed the flight without incident. After landing I had a mechanic take a look at the pitot-static system. The mechanic removed the airspeed indicator and found that the pitot line and the static line were swapped on the airspeed indicator. The mechanic corrected the issue and reinstalled the airspeed indicator. Although my flight to ultimately completed safely; there are several factors about this situation that I find extremely alarming and worthy of some lessons learned. 1.) this airplane has just completed a pitot-static altimeter inspection several weeks prior with no unusual findings reported by the mechanic. 2.) performing the preflight checks specified by the afm/poh did not reveal anything unusual about the altimeter or pitot-static system. 3.) had this flight been conducted IFR in IMC and had I not had a backup altitude source; this flight could have had a very different outcome. This situation has taught me several lessons that I think every pilot should consider. First is trust; but verify; the work done by your mechanics at each inspection. Second; conduct a thorough ground and flight checkout of your aircraft after any inspection; especially before you plan on flying in hard IMC. And finally; have a backup plan; and backup equipment.

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Original NASA ASRS Text

Title: The pilot of a Beechcraft Bonanza experienced a frozen altimeter and associated transponder readout while conducting a VFR flight. During maintenance troubleshooting it was discovered that the pitot and static lines had been reversed on the altimeter; presumably during the recent pitot/static inspection.

Narrative: Prior to conducting the VFR flight a thorough preflight check was conducted and no discrepancies were noted. The altimeter setting was compared to the field elevation and the altimeter was noted to be approximately 20 FT low but was determined to be within acceptable limits. During takeoff and climb; the airspeed indicator; vertical speed indicator (VSI) and altimeter all appeared to be indicating correctly; although the VSI and altimeter seemed a bit sluggish during the climb. After contacting departure; I noticed that the altimeter froze at 1;500 FT; even though the airplane was still clearly climbing. ATC asked to confirm altitude; which I reported as 1;500 FT. I noted that the backup GPS altimeter was indicating 2;500 FT; and I reported the discrepancy to ATC accordingly. ATC requested me to recycle altitude squawk reporting but the issue persisted. ATC finally requested that I stop squawking mode C altitude reporting. At this point I was about 20 miles from [the destination airport]; so I elected to land as planned; and used the GPS altitude as backup. I completed the flight without incident. After landing I had a Mechanic take a look at the pitot-static system. The Mechanic removed the airspeed indicator and found that the pitot line and the static line were swapped on the airspeed indicator. The Mechanic corrected the issue and reinstalled the airspeed indicator. Although my flight to ultimately completed safely; there are several factors about this situation that I find extremely alarming and worthy of some lessons learned. 1.) This airplane has just completed a pitot-static altimeter inspection several weeks prior with no unusual findings reported by the Mechanic. 2.) Performing the preflight checks specified by the AFM/POH did not reveal anything unusual about the altimeter or pitot-static system. 3.) Had this flight been conducted IFR in IMC and had I not had a backup altitude source; this flight could have had a very different outcome. This situation has taught me several lessons that I think every pilot should consider. First is trust; but verify; the work done by your mechanics at each inspection. Second; conduct a thorough ground and flight checkout of your aircraft after any inspection; especially before you plan on flying in hard IMC. And finally; have a backup plan; and backup equipment.

Data retrieved from NASA's ASRS site as of July 2013 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.