Narrative:

Crj-200 departed kbur on the tower assigned heading of 210 degrees. On initial contact; I radar identified the crj-200 and climbed him to 14;000 feet. The crj-200 read back the assigned altitude. A cessna 172 was VFR at 5;500 feet eastbound landing ksmo; requesting an IFR clearance. The C172 advised he could no longer maintain VFR at 5;500 [feet] and either needed an IFR clearance or a climb to 6;000 feet. Once the C172 entered the lateral confines of my airspace; I issued an IFR clearance to ksmo with a descent to 5;000 feet. After verifying the C172's correct read back; I noticed that the crj-200 had turned direct kvny VOR without a clearance which had placed him on a collision course with the C172. I turned the crj-200 to the southwest; away from the C172. I then issued an immediate left turn to the C172; and went back to the crj-200 and issued an immediate left turn. The closest proximity was 1.62 miles and 200 feet or 1.8 miles and 0 feet. Every once in a while an aircraft turns on their own. Apparently there is some confusion on the VNY9 SID or something. Someone needs to investigate why certain pilots believe they can turn off the tower assigned heading when the SID is a radar vector SID. Common ARTS; without fusion; contributed to the time it took to recognize the aircraft had turned without clearance. Had fusion radar been in use; I may have recognized it sooner. Fortunately; we had the staffing to have sectors split.

Related reports:

Google
 

Original NASA ASRS Text

Title: SCT Controller described a conflict event involving a BUR IFR departure and a VFR aircraft given an IFR clearance to SMO; noting the BUR departure failed to comply with the Tower issued departure heading.

Narrative: CRJ-200 departed KBUR on the Tower assigned heading of 210 degrees. On initial contact; I RADAR identified the CRJ-200 and climbed him to 14;000 feet. The CRJ-200 read back the assigned altitude. A Cessna 172 was VFR at 5;500 feet Eastbound landing KSMO; requesting an IFR clearance. The C172 advised he could no longer maintain VFR at 5;500 [feet] and either needed an IFR clearance or a climb to 6;000 feet. Once the C172 entered the lateral confines of my airspace; I issued an IFR clearance to KSMO with a descent to 5;000 feet. After verifying the C172's correct read back; I noticed that the CRJ-200 had turned direct KVNY VOR without a clearance which had placed him on a collision course with the C172. I turned the CRJ-200 to the Southwest; away from the C172. I then issued an immediate left turn to the C172; and went back to the CRJ-200 and issued an immediate left turn. The closest proximity was 1.62 miles and 200 feet or 1.8 miles and 0 feet. Every once in a while an aircraft turns on their own. Apparently there is some confusion on the VNY9 SID or something. Someone needs to investigate why certain pilots believe they can turn off the Tower assigned heading when the SID is a RADAR vector SID. Common ARTS; without fusion; contributed to the time it took to recognize the aircraft had turned without clearance. Had fusion RADAR been in use; I may have recognized it sooner. Fortunately; we had the staffing to have sectors split.

Data retrieved from NASA's ASRS site as of July 2013 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.