Narrative:

Air carrier X was sebound from 12 NM north of the airport. Air carrier Y was inbound from 16 south of phl, and was descended to 20 from 60 and assigned a 020 heading. Air carrier X was descended from 60 to 20 and assigned a 150 heading. Approximately 1 min later I noticed that air carrier X had not left 60 and asked the flight crew if they could expedite the descent. They replied in the affirmative. I then called traffic to air carrier X that they would follow on the approach. They did not understand the transmission and it was repeated with the crew, then advising the aircraft in sight. A visual approach clearance was issued and an altitude restriction of 20 or below 6 east of the airport was also issued. Air carrier Y was advised they would follow inbound from the north. At this point I noticed that instead of turning south onto a base leg, air carrier X was continuing southeast, away from the airport and would be in conflict with air carrier Y. I called traffic and subsequently turned them eastbound. I then stopped air carrier X descent and advised him to turn towards the airport. Air carrier X reported air carrier Y in sight and was instructed to maintain visual separation. While separation was maintained, it was minimal and could have been much worse. My planning was not what it could have been, however I believe that had air carrier X started their descent when first instructed, the occurrence would never have happened. My belief is that the flight crew was not prepared for this phase of their flight, or in other words, they were 'behind the power curve.'

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Original NASA ASRS Text

Title: ACR X NON ADHERENCE TO ATC CLRNC. FAILED TO DSND AS INSTRUCTED. PLTDEV.

Narrative: ACR X WAS SEBOUND FROM 12 NM N OF THE ARPT. ACR Y WAS INBOUND FROM 16 S OF PHL, AND WAS DSNDED TO 20 FROM 60 AND ASSIGNED A 020 HDG. ACR X WAS DSNDED FROM 60 TO 20 AND ASSIGNED A 150 HDG. APPROX 1 MIN LATER I NOTICED THAT ACR X HAD NOT LEFT 60 AND ASKED THE FLC IF THEY COULD EXPEDITE THE DSCNT. THEY REPLIED IN THE AFFIRMATIVE. I THEN CALLED TFC TO ACR X THAT THEY WOULD FOLLOW ON THE APCH. THEY DID NOT UNDERSTAND THE XMISSION AND IT WAS REPEATED WITH THE CREW, THEN ADVISING THE ACFT IN SIGHT. A VISUAL APCH CLRNC WAS ISSUED AND AN ALT RESTRICTION OF 20 OR BELOW 6 E OF THE ARPT WAS ALSO ISSUED. ACR Y WAS ADVISED THEY WOULD FOLLOW INBOUND FROM THE N. AT THIS POINT I NOTICED THAT INSTEAD OF TURNING S ONTO A BASE LEG, ACR X WAS CONTINUING SE, AWAY FROM THE ARPT AND WOULD BE IN CONFLICT WITH ACR Y. I CALLED TFC AND SUBSEQUENTLY TURNED THEM EBOUND. I THEN STOPPED ACR X DSCNT AND ADVISED HIM TO TURN TOWARDS THE ARPT. ACR X RPTED ACR Y IN SIGHT AND WAS INSTRUCTED TO MAINTAIN VISUAL SEPARATION. WHILE SEPARATION WAS MAINTAINED, IT WAS MINIMAL AND COULD HAVE BEEN MUCH WORSE. MY PLANNING WAS NOT WHAT IT COULD HAVE BEEN, HOWEVER I BELIEVE THAT HAD ACR X STARTED THEIR DSCNT WHEN FIRST INSTRUCTED, THE OCCURRENCE WOULD NEVER HAVE HAPPENED. MY BELIEF IS THAT THE FLC WAS NOT PREPARED FOR THIS PHASE OF THEIR FLT, OR IN OTHER WORDS, THEY WERE 'BEHIND THE PWR CURVE.'

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.