B727 departure ord with instructions to maintain 6000 ft. However, the pilot had read back maintain 16000 ft which was not noticed by the controller. The flight conflicted with an arriving B737 descending to 8000 ft resulting in an operational error.

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Attributes
ACN	407515
Time
Date	199807
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	msl bound lower : 7800 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : ord tracon : pub
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude climbout : initial
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
Experience	controller radar : 14
ASRS Report	407515
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 : published procedure other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 9000 vertical : 300
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Departing B727 was assigned left turn to heading 190 degrees and 6000 ft MSL. He read back 16000 ft and I missed it. Arriving B73B was direct and descending to 8000 ft MSL. I noticed B727 climbing rapidly through 6600 ft and B73B descend through 8700 ft for 8000 ft. I instructed departure aircraft to descend back to 6000 ft as assigned and climbed arrival to 9000 ft. The departure aircraft was through 7800 ft before descending. Although I recognized conflict potential before separation was lost, due to rapid climb rate of departing B727, separation was lost even after evasive instructions were issued. I immediately advised supervisor of situation and probable deal, ie, operational error.

Original NASA ASRS Text

Title: B727 DEP ORD WITH INSTRUCTIONS TO MAINTAIN 6000 FT. HOWEVER, THE PLT HAD READ BACK MAINTAIN 16000 FT WHICH WAS NOT NOTICED BY THE CTLR. THE FLT CONFLICTED WITH AN ARRIVING B737 DSNDING TO 8000 FT RESULTING IN AN OPERROR.

Narrative: DEPARTING B727 WAS ASSIGNED L TURN TO HDG 190 DEGS AND 6000 FT MSL. HE READ BACK 16000 FT AND I MISSED IT. ARRIVING B73B WAS DIRECT AND DSNDING TO 8000 FT MSL. I NOTICED B727 CLBING RAPIDLY THROUGH 6600 FT AND B73B DSND THROUGH 8700 FT FOR 8000 FT. I INSTRUCTED DEP ACFT TO DSND BACK TO 6000 FT AS ASSIGNED AND CLBED ARR TO 9000 FT. THE DEP ACFT WAS THROUGH 7800 FT BEFORE DSNDING. ALTHOUGH I RECOGNIZED CONFLICT POTENTIAL BEFORE SEPARATION WAS LOST, DUE TO RAPID CLB RATE OF DEPARTING B727, SEPARATION WAS LOST EVEN AFTER EVASIVE INSTRUCTIONS WERE ISSUED. I IMMEDIATELY ADVISED SUPVR OF SIT AND PROBABLE DEAL, IE, OPERROR.

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.