Non radar approach control air carrier X descent through occupied altitude had less than standard separation from air carrier Y. System error.

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Attributes
ACN	268038
Time
Date	199404
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : bfl
State Reference	CA
Altitude	msl bound lower : 6000 msl bound upper : 6000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bfl
Operator	common carrier : air carrier
Make Model Name	Small Aircraft
Flight Phase	descent other
Route In Use	enroute : direct enroute airway : zla
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Small Aircraft
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller military : 1 controller non radar : 5 controller radar : 1
ASRS Report	268038
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 9000
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Inter Facility Coordination Failure Operational Error

Narrative:

I was working approach control non radar. ZLA sector 3 called an inbound on air carrier X from the northwest. I called ZLA3 to request release for air carrier Y nwbound. ZLA3 advised released, maintain 6000 MSL due to X opposite direction, and that they would hold X at 7000 and cross. I released Y, and passed an estimate for shafter (enf) VOR and requested higher. ZLA3 said no, due to X, as Y clber through 5500. I shipped him to ZLA3. X checked in with the tower controller, not with me as he should have. As soon as I was advised of this, I called ZLA3, simultaneously, with them calling me on the speaker phone, a VFR aircraft was getting some information from me, and about this time I was able to punch into the ZLA line to hear what they were saying. Unbeknownst to me, they were in the middle of a sentence, and I understood them to say the 2 aircraft had passed, when on later review or the tapes, they meant to communication that they had not passed. I cleared Y for visual approach. A couple of mins later ZLA3 called inquiring as to why X had descended.

Original NASA ASRS Text

Title: NON RADAR APCH CTL ACR X DSCNT THROUGH OCCUPIED ALT HAD LTSS FROM ACR Y. SYS ERROR.

Narrative: I WAS WORKING APCH CTL NON RADAR. ZLA SECTOR 3 CALLED AN INBOUND ON ACR X FROM THE NW. I CALLED ZLA3 TO REQUEST RELEASE FOR ACR Y NWBOUND. ZLA3 ADVISED RELEASED, MAINTAIN 6000 MSL DUE TO X OPPOSITE DIRECTION, AND THAT THEY WOULD HOLD X AT 7000 AND CROSS. I RELEASED Y, AND PASSED AN ESTIMATE FOR SHAFTER (ENF) VOR AND REQUESTED HIGHER. ZLA3 SAID NO, DUE TO X, AS Y CLBER THROUGH 5500. I SHIPPED HIM TO ZLA3. X CHKED IN WITH THE TWR CTLR, NOT WITH ME AS HE SHOULD HAVE. AS SOON AS I WAS ADVISED OF THIS, I CALLED ZLA3, SIMULTANEOUSLY, WITH THEM CALLING ME ON THE SPEAKER PHONE, A VFR ACFT WAS GETTING SOME INFO FROM ME, AND ABOUT THIS TIME I WAS ABLE TO PUNCH INTO THE ZLA LINE TO HEAR WHAT THEY WERE SAYING. UNBEKNOWNST TO ME, THEY WERE IN THE MIDDLE OF A SENTENCE, AND I UNDERSTOOD THEM TO SAY THE 2 ACFT HAD PASSED, WHEN ON LATER REVIEW OR THE TAPES, THEY MEANT TO COM THAT THEY HAD NOT PASSED. I CLRED Y FOR VISUAL APCH. A COUPLE OF MINS LATER ZLA3 CALLED INQUIRING AS TO WHY X HAD DSNDED.

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.