Narrative:

I was assigned a heading and instructed to climb to 4000 ft. As I was in the climb; I received another instruction to go direct to lax. I became distraction with the GPS trying to enter the new fix and noticed that I was at 4400 ft. At that time I started a descent and the controller called and said 'your assigned altitude was 4000 ft; you may now climb and maintain 6000 ft.' I apologized and continued the climb to 6000 ft. The distraction was that the GPS would not accept the direct lax change because the flight plan that I had loaded was V23 to lax. This was with a GNS480. I tried repeated times to get the GPS to take the fix and then reverted back to a VOR to get a heading. By then I had lost awareness of my altitude. I also fly with a garmin GNS430 that does allow the previous change scenario to work and did not remember that the 480 won't allow direct to a fix that has been entered in the flight plan with an airway as the route. The above points out that with a moderate workload and a bit of unfamiliarity with equipment; it is very easy to lose situational awareness. In retrospect; I should have started a turn in the general direction I knew to be to lax and waited until I had leveled off at 4000 ft before trying to resolve the GPS issue.

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Original NASA ASRS Text

Title: AN IFR A36 PLT OVERSHOT HIS ASSIGNED ALT BECAUSE OF THE WORKLOAD AND UNFAMILIARITY WHEN THE GPS WOULD NOT ACCEPT A DIRECT TO A FIX COMMAND.

Narrative: I WAS ASSIGNED A HDG AND INSTRUCTED TO CLB TO 4000 FT. AS I WAS IN THE CLB; I RECEIVED ANOTHER INSTRUCTION TO GO DIRECT TO LAX. I BECAME DISTR WITH THE GPS TRYING TO ENTER THE NEW FIX AND NOTICED THAT I WAS AT 4400 FT. AT THAT TIME I STARTED A DSCNT AND THE CTLR CALLED AND SAID 'YOUR ASSIGNED ALT WAS 4000 FT; YOU MAY NOW CLB AND MAINTAIN 6000 FT.' I APOLOGIZED AND CONTINUED THE CLB TO 6000 FT. THE DISTR WAS THAT THE GPS WOULD NOT ACCEPT THE DIRECT LAX CHANGE BECAUSE THE FLT PLAN THAT I HAD LOADED WAS V23 TO LAX. THIS WAS WITH A GNS480. I TRIED REPEATED TIMES TO GET THE GPS TO TAKE THE FIX AND THEN REVERTED BACK TO A VOR TO GET A HDG. BY THEN I HAD LOST AWARENESS OF MY ALT. I ALSO FLY WITH A GARMIN GNS430 THAT DOES ALLOW THE PREVIOUS CHANGE SCENARIO TO WORK AND DID NOT REMEMBER THAT THE 480 WON'T ALLOW DIRECT TO A FIX THAT HAS BEEN ENTERED IN THE FLT PLAN WITH AN AIRWAY AS THE RTE. THE ABOVE POINTS OUT THAT WITH A MODERATE WORKLOAD AND A BIT OF UNFAMILIARITY WITH EQUIP; IT IS VERY EASY TO LOSE SITUATIONAL AWARENESS. IN RETROSPECT; I SHOULD HAVE STARTED A TURN IN THE GENERAL DIRECTION I KNEW TO BE TO LAX AND WAITED UNTIL I HAD LEVELED OFF AT 4000 FT BEFORE TRYING TO RESOLVE THE GPS ISSUE.

Data retrieved from NASA's ASRS site as of January 2009 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.