Air carrier was descended to an occupied altitude resulting in less than standard separation.

Attributes
ACN	137370
Time
Date	199002
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : sby
State Reference	MD
Altitude	msl bound lower : 31000 msl bound upper : 32500
Environment
Flight Conditions	IMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	137370
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller military : 5 controller non radar : 3 controller radar : 4
ASRS Report	137363
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 15600 vertical : 1500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Operational Error

Narrative:

I was relieving the coyle high radar controller. After a complete checklist briefing, the d-side crd dinger sounded. While I was answering it and updating the related flight progress strip, the controller I was relieving descended air carrier X with a crossing restriction to FL290. He then unplugged. I was unaware of this clearance. 1 min later the C/a engaged. Air carrier X was descending from FL330 to FL290 with head-on traffic southbound at FL310, approximately 7 mi away. I cleared air carrier X to expedite a climb back up to FL330. His mode C showed him leaving FL325 when I climbed him. I also called the traffic to air carrier Y that was southbound at FL310. The 2 aircraft came within 2.6 mi and 1500' of each other. I believe this happened because I was distracted at a critical time while assuming control of a sector and missed the bad clearance issued by other controller. Supplemental information from acn 137363: northbound air carrier X was descended to FL290 in order to get into smooth air. A position relief briefing was in progress or had just ended. There was a southbound air carrier Y large transport at FL310 within 15 mi. During the shuffle neither the relieving controller nor the controller being relieved keyed on the traffic at FL310. The controller being relieved left. The controller assuming the position was signing on when 'boom,' the C/a alerted him to the problem. He resolved it.

Original NASA ASRS Text

Title: ACR WAS DESCENDED TO AN OCCUPIED ALT RESULTING IN LESS THAN STANDARD SEPARATION.

Narrative: I WAS RELIEVING THE COYLE HIGH RADAR CTLR. AFTER A COMPLETE CHKLIST BRIEFING, THE D-SIDE CRD DINGER SOUNDED. WHILE I WAS ANSWERING IT AND UPDATING THE RELATED FLT PROGRESS STRIP, THE CTLR I WAS RELIEVING DSNDED ACR X WITH A XING RESTRICTION TO FL290. HE THEN UNPLUGGED. I WAS UNAWARE OF THIS CLRNC. 1 MIN LATER THE C/A ENGAGED. ACR X WAS DSNDING FROM FL330 TO FL290 WITH HEAD-ON TFC SBND AT FL310, APPROX 7 MI AWAY. I CLRED ACR X TO EXPEDITE A CLB BACK UP TO FL330. HIS MODE C SHOWED HIM LEAVING FL325 WHEN I CLBED HIM. I ALSO CALLED THE TFC TO ACR Y THAT WAS SBND AT FL310. THE 2 ACFT CAME WITHIN 2.6 MI AND 1500' OF EACH OTHER. I BELIEVE THIS HAPPENED BECAUSE I WAS DISTRACTED AT A CRITICAL TIME WHILE ASSUMING CTL OF A SECTOR AND MISSED THE BAD CLRNC ISSUED BY OTHER CTLR. SUPPLEMENTAL INFO FROM ACN 137363: NBOUND ACR X WAS DSNDED TO FL290 IN ORDER TO GET INTO SMOOTH AIR. A POS RELIEF BRIEFING WAS IN PROGRESS OR HAD JUST ENDED. THERE WAS A SBND ACR Y LGT AT FL310 WITHIN 15 MI. DURING THE SHUFFLE NEITHER THE RELIEVING CTLR NOR THE CTLR BEING RELIEVED KEYED ON THE TFC AT FL310. THE CTLR BEING RELIEVED LEFT. THE CTLR ASSUMING THE POS WAS SIGNING ON WHEN 'BOOM,' THE C/A ALERTED HIM TO THE PROB. HE RESOLVED IT.

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.