Control instructions were insufficient to prevent a loss of separation between opposite direction tr...

Attributes
ACN	125969
Time
Date	198910
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : lrp airport : lns
State Reference	PA
Altitude	msl bound lower : 4300 msl bound upper : 5000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cxy
Operator	common carrier : air carrier
Make Model Name	Medium Transport, High Wing, 2 Turboprop Eng
Flight Phase	cruise other
Route In Use	arrival other
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 4 flight time total : 85
ASRS Report	125969
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 10500 vertical : 700
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Operational Error

Narrative:

Mdt X level 5000', esebound for ILS approach at lns. Small aircraft Y level 5000', wbound for ILS approach at cxy. Approximately 1 1 /2 mins after assuming the harrisburg arrival/departure sector, I became aware of the conflict, with the aircraft 6-7 mi apart. I issued a turn to mdt X to heading 050 degree, but believing the aircraft was not on my frequency (a handoff had been accomplished), I warned the next sector of the conflict via override, and immediately turned small aircraft Y north and descended him, calling the traffic. During the time I was on landline with other sector, mdt X acknowledged the turn. I did not expect, and did not hear, the response. Believing mdt X to still be heading 120 degree, the turn north for small aircraft Y should have resolved the conflict. Failure to hear mdt X's readback resulted in loss of longitudinal separation prior to the establishment of vertical separation. In retrospect, it was unclear on the briefing whether mdt X was still on the frequency.

Original NASA ASRS Text

Title: CTL INSTRUCTIONS WERE INSUFFICIENT TO PREVENT A LOSS OF SEPARATION BETWEEN OPPOSITE DIRECTION TRAFFIC.

Narrative: MDT X LEVEL 5000', ESEBOUND FOR ILS APCH AT LNS. SMA Y LEVEL 5000', WBOUND FOR ILS APCH AT CXY. APPROX 1 1 /2 MINS AFTER ASSUMING THE HARRISBURG ARR/DEP SECTOR, I BECAME AWARE OF THE CONFLICT, WITH THE ACFT 6-7 MI APART. I ISSUED A TURN TO MDT X TO HDG 050 DEG, BUT BELIEVING THE ACFT WAS NOT ON MY FREQ (A HANDOFF HAD BEEN ACCOMPLISHED), I WARNED THE NEXT SECTOR OF THE CONFLICT VIA OVERRIDE, AND IMMEDIATELY TURNED SMA Y N AND DESCENDED HIM, CALLING THE TFC. DURING THE TIME I WAS ON LANDLINE WITH OTHER SECTOR, MDT X ACKNOWLEDGED THE TURN. I DID NOT EXPECT, AND DID NOT HEAR, THE RESPONSE. BELIEVING MDT X TO STILL BE HDG 120 DEG, THE TURN N FOR SMA Y SHOULD HAVE RESOLVED THE CONFLICT. FAILURE TO HEAR MDT X'S READBACK RESULTED IN LOSS OF LONGITUDINAL SEPARATION PRIOR TO THE ESTABLISHMENT OF VERTICAL SEPARATION. IN RETROSPECT, IT WAS UNCLEAR ON THE BRIEFING WHETHER MDT X WAS STILL ON THE FREQ.

Data retrieved from NASA's ASRS site as of August 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.

Control instructions were insufficient to prevent a loss of separation between opposite direction traffic.