Narrative:

While departing sjc via the sjc 8, moony SID, departure control gave us an early turn (prior to the sjc 1.8 DME point) to 110 degrees to reintercept the oak 121 degree radial. Passing through approximately 3600 ft, bay departure issued us an amended clearance altitude of 4000 ft (the SID initial clearance limit altitude is 5000 ft). The aircraft performance/energy level and climb rate was too high to capture 4000 ft and protect its '1G' performance parameter in autoflt. Autoplt was disconnected and aircraft reached 4400 ft before ascent was arrested and aircraft returned to 4000 ft. We told bay departure that the clearance to 4000 ft came too late and informed him of our altitude (4400 ft) and our return to 4000 ft. About this same time we got a TA on the TCASII for traffic about our 10 O'clock position at 6-7 mi, approximately 1000 ft higher, closing to within 600 ft higher than we were. As the TA ended (no RA) bay departure responded with words to the effect of 'it doesn't matter anyway' and reclred us to climb and maintain 15000 ft. At no time was the traffic called out to us or a reason given for the amended clearance to 4000 ft. It just came too late for us to capture 4000 ft before passing slightly above.

Related reports:

Google
 

Original NASA ASRS Text

Title: A CLBING A320 OVERSHOOTS HIS AMENDED ALT DURING THE DEP PROC AT SJC, CA.

Narrative: WHILE DEPARTING SJC VIA THE SJC 8, MOONY SID, DEP CTL GAVE US AN EARLY TURN (PRIOR TO THE SJC 1.8 DME POINT) TO 110 DEGS TO REINTERCEPT THE OAK 121 DEG RADIAL. PASSING THROUGH APPROX 3600 FT, BAY DEP ISSUED US AN AMENDED CLRNC ALT OF 4000 FT (THE SID INITIAL CLRNC LIMIT ALT IS 5000 FT). THE ACFT PERFORMANCE/ENERGY LEVEL AND CLB RATE WAS TOO HIGH TO CAPTURE 4000 FT AND PROTECT ITS '1G' PERFORMANCE PARAMETER IN AUTOFLT. AUTOPLT WAS DISCONNECTED AND ACFT REACHED 4400 FT BEFORE ASCENT WAS ARRESTED AND ACFT RETURNED TO 4000 FT. WE TOLD BAY DEP THAT THE CLRNC TO 4000 FT CAME TOO LATE AND INFORMED HIM OF OUR ALT (4400 FT) AND OUR RETURN TO 4000 FT. ABOUT THIS SAME TIME WE GOT A TA ON THE TCASII FOR TFC ABOUT OUR 10 O'CLOCK POS AT 6-7 MI, APPROX 1000 FT HIGHER, CLOSING TO WITHIN 600 FT HIGHER THAN WE WERE. AS THE TA ENDED (NO RA) BAY DEP RESPONDED WITH WORDS TO THE EFFECT OF 'IT DOESN'T MATTER ANYWAY' AND RECLRED US TO CLB AND MAINTAIN 15000 FT. AT NO TIME WAS THE TFC CALLED OUT TO US OR A REASON GIVEN FOR THE AMENDED CLRNC TO 4000 FT. IT JUST CAME TOO LATE FOR US TO CAPTURE 4000 FT BEFORE PASSING SLIGHTLY ABOVE.

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.