<< >> NASA ASRS Report 465461, March 2000

ZAU developmental controller overlooks potential opposite direction conflict when descending an air carrier to meet LOA requirements.

Attributes
ACN	465461
Time
Date	200003
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : fwa.vortac
State Reference	IN
Altitude	msl bound lower : 20000 msl bound upper : 21000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zau.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar instruction : trainee
Qualification	controller : developmental
ASRS Report	465461
Person 2
Affiliation	government : faa
Function	controller : radar instruction : instructor
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment : conflict alert other controllera other controllerb
Resolutory Action	controller : issued advisory controller : issued new clearance
Consequence	faa : investigated
Miss Distance	horizontal : 19000 vertical : 100
Supplementary
Problem Areas	Airspace Structure ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Aircraft #2 was wbound at FL200. Aircraft #1 was sebound at FL210. Aircraft #1 needed a descent clearance to FL190 to meet a LOA with ZID and to avoid a conflict with a nebound jet at FL210. In concentrating on these issues, I somehow overlooked the potential conflict with the aircraft #2. By the time I discovered the error, standard separation was lost. Traffic was issued and vector heading was issued to aircraft #1 to maximize the existing separation. Aircraft #1 was also asked to expedite the descent. The error was discovered simultaneously by another controller at an adjacent sector and by 'conflict alert.' at the time of the error, traffic was light but was poised for the afternoon rush which began about 5 mins later. As I recall, there were only 4 or 5 aircraft on the frequency at the time.

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Original NASA ASRS Text

Title: ZAU DEVELOPMENTAL CTLR OVERLOOKS POTENTIAL OPPOSITE DIRECTION CONFLICT WHEN DSNDING AN ACR TO MEET LOA REQUIREMENTS.

Narrative: ACFT #2 WAS WBOUND AT FL200. ACFT #1 WAS SEBOUND AT FL210. ACFT #1 NEEDED A DSCNT CLRNC TO FL190 TO MEET A LOA WITH ZID AND TO AVOID A CONFLICT WITH A NEBOUND JET AT FL210. IN CONCENTRATING ON THESE ISSUES, I SOMEHOW OVERLOOKED THE POTENTIAL CONFLICT WITH THE ACFT #2. BY THE TIME I DISCOVERED THE ERROR, STANDARD SEPARATION WAS LOST. TFC WAS ISSUED AND VECTOR HDG WAS ISSUED TO ACFT #1 TO MAXIMIZE THE EXISTING SEPARATION. ACFT #1 WAS ALSO ASKED TO EXPEDITE THE DSCNT. THE ERROR WAS DISCOVERED SIMULTANEOUSLY BY ANOTHER CTLR AT AN ADJACENT SECTOR AND BY 'CONFLICT ALERT.' AT THE TIME OF THE ERROR, TFC WAS LIGHT BUT WAS POISED FOR THE AFTERNOON RUSH WHICH BEGAN ABOUT 5 MINS LATER. AS I RECALL, THERE WERE ONLY 4 OR 5 ACFT ON THE FREQ AT THE TIME.

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.