ARTCC radar controller descended an air carrier L1011 to 17000 ft. Flight crew read back the wrong altitude and the controller didn't catch the error until the L1011 went through 17000 ft and the conflict alert activated showing less than standard separation occurring with an air carrier L188 at 16000 ft.

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Attributes
ACN	354651
Time
Date	199611
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : shb
State Reference	IN
Altitude	msl bound lower : 16700 msl bound upper : 17000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	L-1011 Tri-Star All Series
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Electra L-188
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 7
ASRS Report	354651
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 10200 vertical : 700
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Pilot Deviation

Narrative:

Air carrier X en route to cvg issued clearance to 17000 ft. Air carrier X read back 16000 ft. Air carrier X was observed going through 16800 ft and control instructions were reissued to maintain 17000 ft, turn 30 degrees right, current altimeter, and then to state altitude. Traffic was issued to the air carrier X and assigned altitude was requested. Air carrier X stated '17000 ft, previously issued 16000 ft.' conflict alert activated only seconds after air carrier X descended through 17000 ft. Not giving any warning of possible resolution to error prior to loss of separation. The air carrier X had already entered the receiving controller's airspace but was not switched so that traffic could be called. At the time the traffic call was to be made, a 'green light coordination' call occurred and therefore the opportunity to alert air carrier X to his traffic was missed.

Original NASA ASRS Text

Title: ARTCC RADAR CTLR DSNDED AN ACR L1011 TO 17000 FT. FLC READ BACK THE WRONG ALT AND THE CTLR DIDN'T CATCH THE ERROR UNTIL THE L1011 WENT THROUGH 17000 FT AND THE CONFLICT ALERT ACTIVATED SHOWING LTSS OCCURRING WITH AN ACR L188 AT 16000 FT.

Narrative: ACR X ENRTE TO CVG ISSUED CLRNC TO 17000 FT. ACR X READ BACK 16000 FT. ACR X WAS OBSERVED GOING THROUGH 16800 FT AND CTL INSTRUCTIONS WERE REISSUED TO MAINTAIN 17000 FT, TURN 30 DEGS R, CURRENT ALTIMETER, AND THEN TO STATE ALT. TFC WAS ISSUED TO THE ACR X AND ASSIGNED ALT WAS REQUESTED. ACR X STATED '17000 FT, PREVIOUSLY ISSUED 16000 FT.' CONFLICT ALERT ACTIVATED ONLY SECONDS AFTER ACR X DSNDED THROUGH 17000 FT. NOT GIVING ANY WARNING OF POSSIBLE RESOLUTION TO ERROR PRIOR TO LOSS OF SEPARATION. THE ACR X HAD ALREADY ENTERED THE RECEIVING CTLR'S AIRSPACE BUT WAS NOT SWITCHED SO THAT TFC COULD BE CALLED. AT THE TIME THE TFC CALL WAS TO BE MADE, A 'GREEN LIGHT COORD' CALL OCCURRED AND THEREFORE THE OPPORTUNITY TO ALERT ACR X TO HIS TFC WAS MISSED.

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.