Narrative:

Early in the morning ; I was called by my company to fly a lifeguard; part 135 flight for a patient pickup to transport and return to grb. The IFR clearance was climb and maintain 3000 ft to expect 12;000 ft in 10 minutes. Departing grb; I reported to departure out of 1800 ft; climbing to 3000 ft. I was then cleared to 12;000 ft on course. At 12;000 ft indicated altitude; I reported to center to be level at 12;000 ft. After several minutes; center asked to confirm altitude. My reply was; level at 12;000 ft. Center asked to confirm my altitude setting. It was set at 28.96. Center then informed me that the actual setting was 29.96. I immediately reset the correct setting and informed center. I was descended to 12;000 ft. There was not any conflicting traffic and nothing more was said. The flight was continued without further incident. Contributing factors were; I believe; a rush to get going due to being a lifeguard flight. Also the previous few days the altitude setting had been in the 28's; which was still set in the aircraft from a previous flight. I did receive the ATIS which stated the altitude setting at 29.96. The altimeter was reading 700 ft; which is approximately field elevation. In reality; it was reading -700 ft. My mistake was assuming the field elevation and indicated elevation was the same. To prevent this from happening again; I will double check ATIS info and not assume the altimeter is reading the correct field elevation.

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Original NASA ASRS Text

Title: King Air pilot reports mis-setting the altimeter prior to departure to 28.96 when the actual setting is 29.96. Error is noticed by ATC after level off and brought to the reporters attention.

Narrative: Early in the morning ; I was called by my company to fly a Lifeguard; Part 135 flight for a patient pickup to transport and return to GRB. The IFR clearance was climb and maintain 3000 FT to expect 12;000 FT in 10 minutes. Departing GRB; I reported to Departure out of 1800 FT; climbing to 3000 FT. I was then cleared to 12;000 FT on course. At 12;000 FT indicated altitude; I reported to Center to be level at 12;000 FT. After several minutes; Center asked to confirm altitude. My reply was; level at 12;000 FT. Center asked to confirm my altitude setting. It was set at 28.96. Center then informed me that the actual setting was 29.96. I immediately reset the correct setting and informed Center. I was descended to 12;000 FT. There was not any conflicting traffic and nothing more was said. The flight was continued without further incident. Contributing factors were; I believe; a rush to get going due to being a Lifeguard flight. Also the previous few days the altitude setting had been in the 28's; which was still set in the aircraft from a previous flight. I did receive the ATIS which stated the altitude setting at 29.96. The altimeter was reading 700 FT; which is approximately field elevation. In reality; it was reading -700 FT. My mistake was assuming the field elevation and indicated elevation was the same. To prevent this from happening again; I will double check ATIS info and not assume the altimeter is reading the correct field elevation.

Data retrieved from NASA's ASRS site as of April 2012 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.