Narrative:

Aircraft X departed northwest bound; IFR; and was instructed to climb and maintain 3000 feet. I issued traffic to aircraft X on aircraft Y; southwest bound level at 4000 feet; IFR; 6 miles northeast. I observed aircraft X altitude climb to 3300 feet. I instructed aircraft X to maintain 3000 feet and issued traffic again on the aircraft Y; who was still level at 4000 feet southwest bound. When aircraft X replied; and advised he was correcting; the altitude indicated 3400 feet. Aircraft Y passed behind aircraft X; and as I advised aircraft X that traffic was no longer a factor; I observed aircraft X in a decent back to 3000 feet.

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Original NASA ASRS Text

Title: TRACON Controller described an altitude excursion causing an loss of separation; the aircraft in questions reported equipment problems as the primary contributing factor.

Narrative: Aircraft X departed Northwest bound; IFR; and was instructed to climb and maintain 3000 feet. I issued traffic to Aircraft X on Aircraft Y; Southwest bound level at 4000 feet; IFR; 6 miles Northeast. I observed Aircraft X altitude climb to 3300 feet. I instructed Aircraft X to maintain 3000 feet and issued traffic again on the Aircraft Y; who was still level at 4000 feet Southwest bound. When Aircraft X replied; and advised he was correcting; the altitude indicated 3400 feet. Aircraft Y passed behind Aircraft X; and as I advised Aircraft X that traffic was no longer a factor; I observed Aircraft X in a decent back to 3000 feet.

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.