<< >> NASA ASRS Report 531168, November 2001

ZAU trainee controller allowed opposite direction traffic, wbound climbing and eastbound descending, to conflict.

Attributes
ACN	531168
Time
Date	200111
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : bae.vortac
State Reference	WI
Altitude	msl bound lower : 19000 msl bound upper : 20000
Environment
Flight Conditions	IMC
Weather Elements	Ice Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau.artcc tower : mia.tower
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	climbout : intermediate altitude
Route In Use	departure : on vectors
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
Navigation In Use	other vortac
Flight Phase	climbout : intermediate altitude descent : approach
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar instruction : instructor
Qualification	controller : radar
Experience	controller limited radar : 15 controller non radar : 16 controller radar : 14 controller time certified in position1 : 14
ASRS Report	531168
Person 2
Affiliation	government : faa
Function	controller : radar instruction : trainee
Qualification	controller : developmental
ASRS Report	531169
Events
Anomaly	altitude deviation : overshoot non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment : conflict alert other controllera other controllerb other flight crewa other flight crewb
Consequence	faa : investigated
Miss Distance	horizontal : 24000 vertical : 400
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X was eastbound climbing to FL230, turning from 090 degrees to direct grr VORTAC. Air carrier Y was wbound, descending to 14000 ft, direct sudds, direct mke. Strong westerly winds probably extended the turn direct grr, and I observed that lateral separation would be lost. I issued FL200 to air carrier Y, as the radar indicated descent through FL208. Air carrier Y leveled at FL200. I issued FL190 to air carrier X, but they were through FL190 already, and had to descend back, resulting in 400 ft vertical, 4.5 NM lateral. I could have maintained separation by stopping air carrier X first, or by telling both aircraft to 'maintain present altitude.' specifically, I underestimated air carrier X climb rate, in addition to initially projecting lateral separation.

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Original NASA ASRS Text

Title: ZAU TRAINEE CTLR ALLOWED OPPOSITE DIRECTION TFC, WBOUND CLBING AND EBOUND DSNDING, TO CONFLICT.

Narrative: ACR X WAS EBOUND CLBING TO FL230, TURNING FROM 090 DEGS TO DIRECT GRR VORTAC. ACR Y WAS WBOUND, DSNDING TO 14000 FT, DIRECT SUDDS, DIRECT MKE. STRONG WESTERLY WINDS PROBABLY EXTENDED THE TURN DIRECT GRR, AND I OBSERVED THAT LATERAL SEPARATION WOULD BE LOST. I ISSUED FL200 TO ACR Y, AS THE RADAR INDICATED DSCNT THROUGH FL208. ACR Y LEVELED AT FL200. I ISSUED FL190 TO ACR X, BUT THEY WERE THROUGH FL190 ALREADY, AND HAD TO DSND BACK, RESULTING IN 400 FT VERT, 4.5 NM LATERAL. I COULD HAVE MAINTAINED SEPARATION BY STOPPING ACR X FIRST, OR BY TELLING BOTH ACFT TO 'MAINTAIN PRESENT ALT.' SPECIFICALLY, I UNDERESTIMATED ACR X CLB RATE, IN ADDITION TO INITIALLY PROJECTING LATERAL SEPARATION.

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.