Narrative:

We were holding at darts intersection as published at 7000 ft when socal approach called out traffic at 11 O'clock position, 4 mi, 7500 ft. Both the captain and I were looking for the traffic. The piper lance descended to 7000 ft, breaking his assigned altitude of 7500 ft. We saw the traffic at 12 O'clock position, horizontally about 200 ft, and we took evasive action by banking sharply to the left to a westerly heading. The pilot of the lance realized his mistake of descending below his altitude and apologized. Socal ensued in giving the pilot a telephone number to call. The problem was the descent of the pilot of the piper lance to our assigned altitude. It could be avoided by maintaining larger separation between private aircraft and acrs. Also, closer monitoring of air traffic in busy airspace areas would be advisory.

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Original NASA ASRS Text

Title: AN EMB120 FO RPT ON AN NMAC WITH A VFR PIPER PA32R-300 WHO HAD DSNDED TOWARDS THE HOLDING ALT ASSIGNED TO THE ACR 35 MI SE OF LHS, CA.

Narrative: WE WERE HOLDING AT DARTS INTXN AS PUBLISHED AT 7000 FT WHEN SOCAL APCH CALLED OUT TFC AT 11 O'CLOCK POS, 4 MI, 7500 FT. BOTH THE CAPT AND I WERE LOOKING FOR THE TFC. THE PIPER LANCE DSNDED TO 7000 FT, BREAKING HIS ASSIGNED ALT OF 7500 FT. WE SAW THE TFC AT 12 O'CLOCK POS, HORIZLY ABOUT 200 FT, AND WE TOOK EVASIVE ACTION BY BANKING SHARPLY TO THE L TO A WESTERLY HDG. THE PLT OF THE LANCE REALIZED HIS MISTAKE OF DSNDING BELOW HIS ALT AND APOLOGIZED. SOCAL ENSUED IN GIVING THE PLT A TELEPHONE NUMBER TO CALL. THE PROB WAS THE DSCNT OF THE PLT OF THE PIPER LANCE TO OUR ASSIGNED ALT. IT COULD BE AVOIDED BY MAINTAINING LARGER SEPARATION BTWN PVT ACFT AND ACRS. ALSO, CLOSER MONITORING OF AIR TFC IN BUSY AIRSPACE AREAS WOULD BE ADVISORY.

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.