ZOB controller experienced operational error at approximately FL230 when air carrier was descended through occupied altitude; WX deviations listed as contributory.

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Attributes
ACN	737230
Time
Date	200705
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : crl.vortac
State Reference	MI
Altitude	msl bound lower : 23000 msl bound upper : 23700
Environment
Flight Conditions	IMC
Weather Elements	Thunderstorm
Aircraft 1
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air taxi
Make Model Name	Beech 1900
Operating Under FAR Part	Part 135
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 16
ASRS Report	737230
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller time certified in position2 : 4
ASRS Report	737231
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment : conflict alert aircraft equipment : tcas other controllera other controllerb other flight crewa
Resolutory Action	controller : issued alert controller : issued new clearance flight crew : took evasive action
Consequence	faa : investigated
Miss Distance	horizontal : 17500 vertical : 700
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Very complex with WX and deviations. Air carrier X and air carrier Y were landing cle. Got busy with deviations. Air carrier X checked on for 3RD or 4TH time and I descended him; then noticed not clear of air carrier Y and stopped him; 3.71 mi 700 ft clear of air carrier X at FL240; air carrier Y at FL230. Supplemental information from acn 737231: due to WX deviations and tmu re-routing extra aircraft into WX; a complex sector was occurring. Cleveland approach put us into the hold with short notice and there was WX over our holding fix. The radar control overlooking the traffic and descended the B737 into the B1900's altitude. Then climbed the B737 back up while separation was lost.

Original NASA ASRS Text

Title: ZOB CTLR EXPERIENCED OPERROR AT APPROX FL230 WHEN ACR WAS DESCENDED THROUGH OCCUPIED ALT; WX DEVIATIONS LISTED AS CONTRIBUTORY.

Narrative: VERY COMPLEX WITH WX AND DEVS. ACR X AND ACR Y WERE LNDG CLE. GOT BUSY WITH DEVS. ACR X CHKED ON FOR 3RD OR 4TH TIME AND I DSNDED HIM; THEN NOTICED NOT CLR OF ACR Y AND STOPPED HIM; 3.71 MI 700 FT CLR OF ACR X AT FL240; ACR Y AT FL230. SUPPLEMENTAL INFO FROM ACN 737231: DUE TO WX DEVS AND TMU RE-ROUTING EXTRA ACFT INTO WX; A COMPLEX SECTOR WAS OCCURRING. CLEVELAND APCH PUT US INTO THE HOLD WITH SHORT NOTICE AND THERE WAS WX OVER OUR HOLDING FIX. THE RADAR CTL OVERLOOKING THE TFC AND DSNDED THE B737 INTO THE B1900'S ALT. THEN CLBED THE B737 BACK UP WHILE SEPARATION WAS LOST.

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.