ZID controller experienced operational error at FL310 when descending traffic through occupied altit...

Attributes
ACN	734814
Time
Date	200704
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : bkw.vortac
State Reference	WV
Altitude	msl single value : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid.artcc
Operator	general aviation : corporate
Make Model Name	Beechjet 400
Operating Under FAR Part	Part 91
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zid.artcc
Operator	common carrier : air carrier
Make Model Name	EMB ERJ 145 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 12 controller radar : 1.2 controller time certified in position1 : 1 controller time certified in position2 : 2
ASRS Report	734814
Person 2
Affiliation	government : faa
Function	controller : handoff position
Qualification	controller : radar
Experience	controller military : 3 controller non radar : 5 controller radar : 12 controller time certified in position1 : 2 controller time certified in position2 : 1
ASRS Report	734815
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment : conflict alert other controllera other controllerb
Resolutory Action	controller : issued new clearance controller : issued alert
Consequence	faa : investigated
Miss Distance	horizontal : 27000 vertical : 500
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was working the 2 aircraft (BE40-E145) one was level at FL320 the other level at FL310. I overlooked the FL310 traffic and descended the FL320 traffic through his altitude. I immediately climbed the FL320 traffic back to FL320 and asked for a report to verify him level at FL320. My first attempt was blocked by another aircraft. My second attempt was successful but separation was lost. Supplemental information from acn 734815: for approximately 30-40 mins and traffic was building in volume and complexity. I was doing offline coordination with ZDC and performing uret functions during the time of the incident. I looked at the pud and saw the 2 aircraft involved appeared to be in conflict; but conflict alert had not activated yet. I asked the r-side if he was doing what the data blocks reflected. I believe this drew the attention of the radar controller to that situation.

Original NASA ASRS Text

Title: ZID CTLR EXPERIENCED OPERROR AT FL310 WHEN DESCENDING TFC THROUGH OCCUPIED ALT.

Narrative: I WAS WORKING THE 2 ACFT (BE40-E145) ONE WAS LEVEL AT FL320 THE OTHER LEVEL AT FL310. I OVERLOOKED THE FL310 TFC AND DSNDED THE FL320 TFC THROUGH HIS ALT. I IMMEDIATELY CLBED THE FL320 TFC BACK TO FL320 AND ASKED FOR A RPT TO VERIFY HIM LEVEL AT FL320. MY FIRST ATTEMPT WAS BLOCKED BY ANOTHER ACFT. MY SECOND ATTEMPT WAS SUCCESSFUL BUT SEPARATION WAS LOST. SUPPLEMENTAL INFO FROM ACN 734815: FOR APPROX 30-40 MINS AND TFC WAS BUILDING IN VOLUME AND COMPLEXITY. I WAS DOING OFFLINE COORD WITH ZDC AND PERFORMING URET FUNCTIONS DURING THE TIME OF THE INCIDENT. I LOOKED AT THE PUD AND SAW THE 2 ACFT INVOLVED APPEARED TO BE IN CONFLICT; BUT CONFLICT ALERT HAD NOT ACTIVATED YET. I ASKED THE R-SIDE IF HE WAS DOING WHAT THE DATA BLOCKS REFLECTED. I BELIEVE THIS DREW THE ATTN OF THE RADAR CTLR TO THAT SIT.

Data retrieved from NASA's ASRS site as of January 2009 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.

ZID controller experienced operational error at FL310 when descending traffic through occupied altitude.