<< >> NASA ASRS Report 647670, February 2005

ZHU controller experienced operational error at FL280 because of confusion regarding adjacent ZFW controller's assigned altitude.

Attributes
ACN	647670
Time
Date	200502
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : cll.vortac
State Reference	TX
Altitude	msl single value : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu.artcc artcc : zfw.artcc tower : geu.tower
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zhu.artcc artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 15
ASRS Report	647670
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	faa : investigated
Miss Distance	horizontal : 27000 vertical : 600
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Working the bilee high altitude sector during a daily rush. I took the handoff on air carrier X at FL290. I also took a handoff on air carrier Y. The data block indicated air carrier Y was climbing to FL370; about 6 mi behind air carrier X. When air carrier X entered my 'dump box;' I issued a lower altitude of FL240. At that time I realized that ZFW was not climbing air carrier X to FL370; but rather had air carrier Y stopping at FL280. I reissued FL290 to air carrier X. Air carrier X had already began a descent. Separation was lost before air carrier X leveled again at FL290. There was no indication that air carrier Y was assigned anything other than FL370.

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Original NASA ASRS Text

Title: ZHU CTLR EXPERIENCED OPERROR AT FL280 BECAUSE OF CONFUSION REGARDING ADJACENT ZFW CTLR'S ASSIGNED ALT.

Narrative: WORKING THE BILEE HIGH ALT SECTOR DURING A DAILY RUSH. I TOOK THE HDOF ON ACR X AT FL290. I ALSO TOOK A HDOF ON ACR Y. THE DATA BLOCK INDICATED ACR Y WAS CLBING TO FL370; ABOUT 6 MI BEHIND ACR X. WHEN ACR X ENTERED MY 'DUMP BOX;' I ISSUED A LOWER ALT OF FL240. AT THAT TIME I REALIZED THAT ZFW WAS NOT CLBING ACR X TO FL370; BUT RATHER HAD ACR Y STOPPING AT FL280. I REISSUED FL290 TO ACR X. ACR X HAD ALREADY BEGAN A DSCNT. SEPARATION WAS LOST BEFORE ACR X LEVELED AGAIN AT FL290. THERE WAS NO INDICATION THAT ACR Y WAS ASSIGNED ANYTHING OTHER THAN FL370.

Data retrieved from NASA's ASRS site as of January 2009 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.