A B727 flight crew turned to a heading rather than descending to an altitude issued by ZFW.

Attributes
ACN	443171
Time
Date	199907
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : duc.vor
State Reference	OK
Altitude	msl bound lower : 27000 msl bound upper : 33800
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	Fokker 100
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	cruise : enroute altitude change
Route In Use	enroute airway : ns.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	443171
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : multi engine pilot : commercial
Events
Anomaly	non adherence : clearance
Independent Detector	other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : returned to intended or assigned course
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Air carrier X was cleared by ZFW to descend from FL350 to FL310. We acknowledged and descended. At FL338, ATC issued us 'air carrier X, right 270 degrees.' I started a right turn to 270 degrees. Although this is approximately 90 degrees to our course, I did not think it unusual since ZFW does this to sequence us for arrs. When on heading 270 degrees, my first officer queried the controller as to the heading. Controller replied it was FL270. He then stopped our descent at FL330 and gave us a heading to 160 degrees. There were no other aircraft at our flight level but there was one at 10 mi and FL310 opposite direction. Deviation from course was no more than 3-4 mi. I was certain I heard 'air carrier X, right 270 degrees' but this is a classic readback hearback situation. The nonstandard phraseology of the controller may have been a factor since I did not hear 'FL270.'

Original NASA ASRS Text

Title: A B727 FLC TURNED TO A HDG RATHER THAN DSNDING TO AN ALT ISSUED BY ZFW.

Narrative: ACR X WAS CLRED BY ZFW TO DSND FROM FL350 TO FL310. WE ACKNOWLEDGED AND DSNDED. AT FL338, ATC ISSUED US 'ACR X, R 270 DEGS.' I STARTED A R TURN TO 270 DEGS. ALTHOUGH THIS IS APPROX 90 DEGS TO OUR COURSE, I DID NOT THINK IT UNUSUAL SINCE ZFW DOES THIS TO SEQUENCE US FOR ARRS. WHEN ON HDG 270 DEGS, MY FO QUERIED THE CTLR AS TO THE HDG. CTLR REPLIED IT WAS FL270. HE THEN STOPPED OUR DSCNT AT FL330 AND GAVE US A HDG TO 160 DEGS. THERE WERE NO OTHER ACFT AT OUR FLT LEVEL BUT THERE WAS ONE AT 10 MI AND FL310 OPPOSITE DIRECTION. DEV FROM COURSE WAS NO MORE THAN 3-4 MI. I WAS CERTAIN I HEARD 'ACR X, R 270 DEGS' BUT THIS IS A CLASSIC READBACK HEARBACK SIT. THE NONSTANDARD PHRASEOLOGY OF THE CTLR MAY HAVE BEEN A FACTOR SINCE I DID NOT HEAR 'FL270.'

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.