Narrative:

Small aircraft X departed wjf, cleared pmd-lynxx 6-VNY climbing to 8000'. Small aircraft Y departed wjf 9 mins later, also cleared pmd-lynxx 6-BUR. As small aircraft X passed pmd, instead of joining the lynxx 6, she appeared to turn north, back toward small aircraft Y, who was about 7 mi in trail. As I observed this I issued a left turn heading 240 degrees. Small aircraft X acknowledged. I then descended small aircraft Y to 5000'. He acknowledged. Small aircraft X continued in a right turn and did not appear to be climbing. I then issued expeditious turn and climb to small aircraft X. There was no reply. Then issued traffic alert to small aircraft Y, who had continued climbing, and instructed him to descend immediately to 5000'. There was no reply from either aircraft. Both aircraft passed the pmd 340002 at the same time, both indicating 6600'. 1 min later small aircraft Y reported level at 5000'. When questioned, small aircraft X reported 'returning to heading 240.' phone conversations with both pilots revealed small aircraft X was being flown with a student and instrument. The instrument apparently was 'busy' in the cockpit. Small aircraft Y apparently thought the climb clearance for small aircraft X was for him, and started climbing west/O acknowledging the transmission. The situation was aggravated because traffic vol was moderate to heavy, and traffic complexity was difficult due to IFR WX, and a small aircraft aircraft with engine problems occurring at the same time. Further, the radar position radio control vol setting was at maximum, and still not satisfactorily loud enough.

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Original NASA ASRS Text

Title: 2 ACFT CAME VERY CLOSE WHEN STUDENT PLT FAILED TO TURN ON COURSE CORRECTLY.

Narrative: SMA X DEPARTED WJF, CLRED PMD-LYNXX 6-VNY CLBING TO 8000'. SMA Y DEPARTED WJF 9 MINS LATER, ALSO CLRED PMD-LYNXX 6-BUR. AS SMA X PASSED PMD, INSTEAD OF JOINING THE LYNXX 6, SHE APPEARED TO TURN N, BACK TOWARD SMA Y, WHO WAS ABOUT 7 MI IN TRAIL. AS I OBSERVED THIS I ISSUED A LEFT TURN HDG 240 DEGS. SMA X ACKNOWLEDGED. I THEN DSNDED SMA Y TO 5000'. HE ACKNOWLEDGED. SMA X CONTINUED IN A RIGHT TURN AND DID NOT APPEAR TO BE CLBING. I THEN ISSUED EXPEDITIOUS TURN AND CLB TO SMA X. THERE WAS NO REPLY. THEN ISSUED TFC ALERT TO SMA Y, WHO HAD CONTINUED CLBING, AND INSTRUCTED HIM TO DSND IMMEDIATELY TO 5000'. THERE WAS NO REPLY FROM EITHER ACFT. BOTH ACFT PASSED THE PMD 340002 AT THE SAME TIME, BOTH INDICATING 6600'. 1 MIN LATER SMA Y RPTED LEVEL AT 5000'. WHEN QUESTIONED, SMA X RPTED 'RETURNING TO HDG 240.' PHONE CONVERSATIONS WITH BOTH PLTS REVEALED SMA X WAS BEING FLOWN WITH A STUDENT AND INSTR. THE INSTR APPARENTLY WAS 'BUSY' IN THE COCKPIT. SMA Y APPARENTLY THOUGHT THE CLB CLRNC FOR SMA X WAS FOR HIM, AND STARTED CLBING W/O ACKNOWLEDGING THE XMISSION. THE SITUATION WAS AGGRAVATED BECAUSE TFC VOL WAS MODERATE TO HEAVY, AND TFC COMPLEXITY WAS DIFFICULT DUE TO IFR WX, AND A SMA ACFT WITH ENG PROBS OCCURRING AT THE SAME TIME. FURTHER, THE RADAR POS RADIO CTL VOL SETTING WAS AT MAX, AND STILL NOT SATISFACTORILY LOUD ENOUGH.

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.