<< >> NASA ASRS Report 188394, September 1991

Controller missed wrong readback of an inbound air carrier resulting in less than standard separation with an outbound air carrier.

Attributes
ACN	188394
Time
Date	199109
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : pmm
State Reference	MI
Altitude	msl bound lower : 12300 msl bound upper : 13000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau tower : ord
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Route In Use	departure other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Route In Use	departure other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 4
ASRS Report	188394
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : developmental
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : published procedure non adherence : required legal separation other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	faa : investigated
Miss Distance	horizontal : 23400 vertical : 700
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was conducting OJT at sparta/squib sector. Air carrier X checked on frequency, ord direct grr at 12000. Air carrier X was cleared to 13000. Air carrier Y checked on frequency grr MMM V84 pappi ord level at 8000. Air carrier Y was cleared to 12000. Readback sounded correct. Traffic was issued to both aircraft. When air carrier Y was asked about his altitude, he said he was out of 13000 for 16000. Air carrier Y was turned to 180 degree heading and air carrier X was turned to 360 degree heading.

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Original NASA ASRS Text

Title: CTLR MISSED WRONG READBACK OF AN INBOUND ACR RESULTING IN LTSS WITH AN OUTBOUND ACR.

Narrative: I WAS CONDUCTING OJT AT SPARTA/SQUIB SECTOR. ACR X CHKED ON FREQ, ORD DIRECT GRR AT 12000. ACR X WAS CLRED TO 13000. ACR Y CHKED ON FREQ GRR MMM V84 PAPPI ORD LEVEL AT 8000. ACR Y WAS CLRED TO 12000. READBACK SOUNDED CORRECT. TFC WAS ISSUED TO BOTH ACFT. WHEN ACR Y WAS ASKED ABOUT HIS ALT, HE SAID HE WAS OUT OF 13000 FOR 16000. ACR Y WAS TURNED TO 180 DEG HDG AND ACR X WAS TURNED TO 360 DEG HDG.

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.