Narrative:

An IFR flight was conducted to a general hospital without incident. The patient was delivered and accepted for care at that time. An IFR flight plan was filed for the return flight. Approach was called and I received a clearance to the airport. The IFR departure was flown as depicted with the autopilot armed to maintain 70 KTS airspeed. I broke out on top; clear; at approximately 3;300 ft MSL and completed the departure climb to 4;000 ft as charted. Approach handed me over to center and they were advised of my altitude at that time. Also; a request for direct IAF; for the GPS 30 approach was made. Request was granted and at that time I had 5;000 ft entered into the altitude a. I pushed the altitude a button to activate a level out at 5;000 ft then started to arm the approach in the GPS. Shortly after... Approach requested my altitude. I checked the altimeter as it passed through 6;000 ft MSL. I advised center I was at 6;000 ft; assigned altitude was 5000; and descending to 5;000 now. The autopilot was disengaged and the aircraft was hand flown down to 5;000. The autopilot was reengaged and the flight was terminated at [destination] after completing the GPS approach.event occurred due to failing to unarm the IAS on the autopilot after reaching departure altitude [and] assuming the aircraft would level out at 5;000 ft. Upon return to the base; the training manual was reviewed to determine why the aircraft didn't level off at 5;000 ft. The manual does state that; 'IAS will be held at the cost of holding altitude.' incident occurred as a result of pilot error and I will review the afcs training manual.

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Original NASA ASRS Text

Title: EC135 pilot climbed 1;000 FT above assigned altitude before being alerted by ATC.

Narrative: An IFR flight was conducted to a General Hospital without incident. The patient was delivered and accepted for care at that time. An IFR flight plan was filed for the return flight. Approach was called and I received a clearance to the airport. The IFR departure was flown as depicted with the autopilot armed to maintain 70 KTS airspeed. I broke out on top; clear; at approximately 3;300 FT MSL and completed the departure climb to 4;000 FT as charted. Approach handed me over to Center and they were advised of my altitude at that time. Also; a request for direct IAF; for the GPS 30 approach was made. Request was granted and at that time I had 5;000 FT entered into the ALT A. I pushed the ALT A button to activate a level out at 5;000 FT then started to arm the approach in the GPS. Shortly after... Approach requested my altitude. I checked the altimeter as it passed through 6;000 FT MSL. I advised Center I was at 6;000 FT; assigned altitude was 5000; and descending to 5;000 now. The autopilot was disengaged and the aircraft was hand flown down to 5;000. The autopilot was reengaged and the flight was terminated at [destination] after completing the GPS approach.Event occurred due to failing to unarm the IAS on the autopilot after reaching departure altitude [and] assuming the aircraft would level out at 5;000 FT. Upon return to the base; the Training Manual was reviewed to determine why the aircraft didn't level off at 5;000 FT. The manual does state that; 'IAS will be held at the cost of holding altitude.' Incident occurred as a result of pilot error and I will review the AFCS Training Manual.

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.