Narrative:

We departed mkc en route to MO49. Our IFR clearance was 'as filed maintain 3000 ft expect 5000 ft within 10 mins.' our takeoff, climb and vector on course were normal. Sometime after our change to departure control, we were cleared to climb to 5000 ft. As we approached 5000 ft I asked the PNF to request 7000 ft. At that point, ATC said he had cleared us to 4000 ft -- not 5000 ft. I had understood 5000 ft, had written it down and set the altitude alerter to 5000 ft. We told ATC we had understood the clearance to be 5000 ft -- not 4000 ft. The controller then told us to 'just stay at 5000 ft and I'll work on higher.' end of incident. I was distracted during early climb by an avionics problem and had asked PNF to handle ATC communications. It is possible that I misunderstood, set the altitude alert and climbed to 5000 ft when in fact I had been cleared to 4000 ft. Perhaps the fact that I had been expecting 5000 ft within 10 mins, per the ATC clearance received prior to takeoff, lured me into the error. The PNF and the ATC controller were apparently not aware of the problem until I requested the climb to 7000 ft. Looks like triple human failure induced in the cockpit by our avionics difficulty and for unknown reasons in the ATC facility.

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Original NASA ASRS Text

Title: PLT OF A PIPER PA23-250 OVERSHOT CLB ALT ON DEP DUE TO DISTR FROM AN AVIONICS PROB AND MISUNDERSTANDING OF CLRNC ALT. ATC NOTED ERROR UPON RPTR'S REQUEST FOR A HIGHER ALT.

Narrative: WE DEPARTED MKC ENRTE TO MO49. OUR IFR CLRNC WAS 'AS FILED MAINTAIN 3000 FT EXPECT 5000 FT WITHIN 10 MINS.' OUR TKOF, CLB AND VECTOR ON COURSE WERE NORMAL. SOMETIME AFTER OUR CHANGE TO DEP CTL, WE WERE CLRED TO CLB TO 5000 FT. AS WE APCHED 5000 FT I ASKED THE PNF TO REQUEST 7000 FT. AT THAT POINT, ATC SAID HE HAD CLRED US TO 4000 FT -- NOT 5000 FT. I HAD UNDERSTOOD 5000 FT, HAD WRITTEN IT DOWN AND SET THE ALT ALERTER TO 5000 FT. WE TOLD ATC WE HAD UNDERSTOOD THE CLRNC TO BE 5000 FT -- NOT 4000 FT. THE CTLR THEN TOLD US TO 'JUST STAY AT 5000 FT AND I'LL WORK ON HIGHER.' END OF INCIDENT. I WAS DISTRACTED DURING EARLY CLB BY AN AVIONICS PROB AND HAD ASKED PNF TO HANDLE ATC COMS. IT IS POSSIBLE THAT I MISUNDERSTOOD, SET THE ALT ALERT AND CLBED TO 5000 FT WHEN IN FACT I HAD BEEN CLRED TO 4000 FT. PERHAPS THE FACT THAT I HAD BEEN EXPECTING 5000 FT WITHIN 10 MINS, PER THE ATC CLRNC RECEIVED PRIOR TO TKOF, LURED ME INTO THE ERROR. THE PNF AND THE ATC CTLR WERE APPARENTLY NOT AWARE OF THE PROB UNTIL I REQUESTED THE CLB TO 7000 FT. LOOKS LIKE TRIPLE HUMAN FAILURE INDUCED IN THE COCKPIT BY OUR AVIONICS DIFFICULTY AND FOR UNKNOWN REASONS IN THE ATC FACILITY.

Data retrieved from NASA's ASRS site as of July 2007 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.