Narrative:

After flying 2 hours at 9500 ft; a descent was made to 3500 ft to cross lax within the 'special flight rules area (sfar)'. The class B 'veil' requires an operating transponder with mode C reporting proper altitude. After departing the sfar and contacting my destination's tower for landing clearance; the tower advised that my transponder mode C was reporting over 10;000 ft when I was descending from 2000 ft to less than 100 ft at the surface. It appears that the blind encoder had stuck at the highest altitude of the flight. The blind encoder is being replaced and the altimeter/encoder/transponder/static system will be re-certified.

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Original NASA ASRS Text

Title: A single engine pilot was told by the Local Controller that his transponder's altitude encoder was stuck at 10;000' after he had already passed through the LAX Special Flight Rules Area at 3;500'.

Narrative: After flying 2 hours at 9500 ft; a descent was made to 3500 ft to cross LAX within the 'special flight rules area (SFAR)'. The Class B 'veil' requires an operating transponder with Mode C reporting proper altitude. After departing the SFAR and contacting my destination's Tower for landing clearance; the Tower advised that my transponder Mode C was reporting over 10;000 ft when I was descending from 2000 ft to less than 100 ft at the surface. It appears that the blind encoder had stuck at the highest altitude of the flight. The blind encoder is being replaced and the altimeter/encoder/transponder/static system will be re-certified.

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.