Narrative:

Clearance delivery told me to stay at or below 3500 ft on departure. On climb out from runway 32R I was given 2 vectors -- 300 degrees, then 270 degrees. After the second vector, departure called and said 'traffic in your 2:30 O'clock position, 2-3 mi at 4500 ft, descending to 4000 ft.' I immediately spotted the traffic (embraer turboprop), but was unable to report it because frequency (departure) was busy and congested. Meanwhile, while watching the other aircraft, I accidentally let my altitude go to 3800 ft. As soon as I noticed it, I pushed the nose over to descend. The other aircraft passed over the top of me when I was at 3600 ft. I'm not sure what the altitude of the other aircraft was at the time. Just prior to the other plane crossing, I called departure and said 'traffic in sight, no factor.' it was a mistake, I should have used autoplt and altitude hold.

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Original NASA ASRS Text

Title: C421 CLBS ABOVE ASSIGNED ALT CAP IN CLASS C AIRSPACE AND CONFLICTS WITH INBOUND ACFT AT OMA.

Narrative: CLRNC DELIVERY TOLD ME TO STAY AT OR BELOW 3500 FT ON DEP. ON CLBOUT FROM RWY 32R I WAS GIVEN 2 VECTORS -- 300 DEGS, THEN 270 DEGS. AFTER THE SECOND VECTOR, DEP CALLED AND SAID 'TFC IN YOUR 2:30 O'CLOCK POS, 2-3 MI AT 4500 FT, DSNDING TO 4000 FT.' I IMMEDIATELY SPOTTED THE TFC (EMBRAER TURBOPROP), BUT WAS UNABLE TO RPT IT BECAUSE FREQ (DEP) WAS BUSY AND CONGESTED. MEANWHILE, WHILE WATCHING THE OTHER ACFT, I ACCIDENTALLY LET MY ALT GO TO 3800 FT. AS SOON AS I NOTICED IT, I PUSHED THE NOSE OVER TO DSND. THE OTHER ACFT PASSED OVER THE TOP OF ME WHEN I WAS AT 3600 FT. I'M NOT SURE WHAT THE ALT OF THE OTHER ACFT WAS AT THE TIME. JUST PRIOR TO THE OTHER PLANE XING, I CALLED DEP AND SAID 'TFC IN SIGHT, NO FACTOR.' IT WAS A MISTAKE, I SHOULD HAVE USED AUTOPLT AND ALT HOLD.

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.