B737-500 and MD80 had less than legal separation in ZFW class a airspace.

Attributes
ACN	533121
Time
Date	200112
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zfw.artcc
State Reference	TX
Altitude	msl bound lower : 24000 msl bound upper : 26000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	B737-500
Operating Under FAR Part	Part 121
Flight Phase	cruise : level cruise : enroute altitude change
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Experience	flight time last 90 days : 240 flight time total : 10000
ASRS Report	533121
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne critical non adherence : far non adherence : published procedure non adherence : required legal separation other anomaly other
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : took evasive action none taken : detected after the fact other
Consequence	other
Miss Distance	vertical : 700
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Altitude deviation by ATC. We were cleared to climb by ATC to FL260, and were climbing out of approximately FL240 when both the captain (PF) and I noticed on TCASII display conflicting traffic. Shortly after, we received an RA to descend and we complied. I notified the fort worth controller, 'we are TCASII descending.' the controller told us to maintain FL240. We are both convinced a mistake was made by the controller to issue FL260 in the first place. The conflicting traffic made a comment about 700 ft separation (an air carrier MD80) but the controller said nothing further. The remainder of the flight was uneventful.

Original NASA ASRS Text

Title: B737-500 AND MD80 HAD LESS THAN LEGAL SEPARATION IN ZFW CLASS A AIRSPACE.

Narrative: ALTDEV BY ATC. WE WERE CLRED TO CLB BY ATC TO FL260, AND WERE CLBING OUT OF APPROX FL240 WHEN BOTH THE CAPT (PF) AND I NOTICED ON TCASII DISPLAY CONFLICTING TFC. SHORTLY AFTER, WE RECEIVED AN RA TO DSND AND WE COMPLIED. I NOTIFIED THE FORT WORTH CTLR, 'WE ARE TCASII DSNDING.' THE CTLR TOLD US TO MAINTAIN FL240. WE ARE BOTH CONVINCED A MISTAKE WAS MADE BY THE CTLR TO ISSUE FL260 IN THE FIRST PLACE. THE CONFLICTING TFC MADE A COMMENT ABOUT 700 FT SEPARATION (AN ACR MD80) BUT THE CTLR SAID NOTHING FURTHER. THE REMAINDER OF THE FLT WAS UNEVENTFUL.

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.