A320 initiates wrong STAR for oak at FL190.

Attributes
ACN	599231
Time
Date	200311
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : pxn.vortac
State Reference	CA
Altitude	msl single value : 19000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla.artcc artcc : zoa.artcc
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	descent : intermediate altitude descent : approach
Route In Use	arrival star : marun
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 215 flight time total : 13600 flight time type : 2300
ASRS Report	599231
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

While descending through FL190 to 13000 ft on the marvn one (pxn.MARVN1) arrival into oak, the ZOA controller asked us if we were flying the marvn one arrival to which we replied in the affirmative. He then cleared us direct to the bored intersection on the panoche two (pxn.PXN2) arrival. We think the previous controller from ZLA, before the handoff to ZOA, may have possibly reclred us to oak via the panoche two arrival, a change from our original marvn one STAR. We may have not caught the change due to a possible ambiguity in the lax controller's clearance phraseology which, to the best of my first officer's and my recollection, sounded like: 'you are cleared to oak via panoche and the arrival' which was read back by us and interpreted as just a reconfirmation of the original STAR of marvn one. Contributing to the ambiguity is that both stars start at pxn VOR. The marvn one is outbound on the 328 degree radial and the panoche two is outbound on the 301 degree radial. There was no apparent issue with the ZOA controller, he just cleared us to bored intersection for the new arrival. We are just expressing doubt over the previous controller's possible ambiguous phraseology. FMS equipped aircraft can sometimes have a navigation interface that is not very transparent to the crew. Combine this with controller phraseology and the expectations of the flight crew to fly a filed STAR that is the norm and 2 different stars that share a common initial fix (pxn), it is easy to see the possible unintended consequences of flying the wrong radial. I recommend that when controllers issue unexpected changes to a STAR in this fast-paced dynamic ATC environment, that they incorporate the word 'now' in the new clearance as a cue to the flight crews that a change is forthcoming in the clearance. They should also adhere to standard phraseology to eliminate ambiguities. An example would be: 'you are now cleared to the abc airport via the xyz arrival.'

Original NASA ASRS Text

Title: A320 INITIATES WRONG STAR FOR OAK AT FL190.

Narrative: WHILE DSNDING THROUGH FL190 TO 13000 FT ON THE MARVN ONE (PXN.MARVN1) ARR INTO OAK, THE ZOA CTLR ASKED US IF WE WERE FLYING THE MARVN ONE ARR TO WHICH WE REPLIED IN THE AFFIRMATIVE. HE THEN CLRED US DIRECT TO THE BORED INTXN ON THE PANOCHE TWO (PXN.PXN2) ARR. WE THINK THE PREVIOUS CTLR FROM ZLA, BEFORE THE HDOF TO ZOA, MAY HAVE POSSIBLY RECLRED US TO OAK VIA THE PANOCHE TWO ARR, A CHANGE FROM OUR ORIGINAL MARVN ONE STAR. WE MAY HAVE NOT CAUGHT THE CHANGE DUE TO A POSSIBLE AMBIGUITY IN THE LAX CTLR'S CLRNC PHRASEOLOGY WHICH, TO THE BEST OF MY FO'S AND MY RECOLLECTION, SOUNDED LIKE: 'YOU ARE CLRED TO OAK VIA PANOCHE AND THE ARR' WHICH WAS READ BACK BY US AND INTERPRETED AS JUST A RECONFIRMATION OF THE ORIGINAL STAR OF MARVN ONE. CONTRIBUTING TO THE AMBIGUITY IS THAT BOTH STARS START AT PXN VOR. THE MARVN ONE IS OUTBOUND ON THE 328 DEG RADIAL AND THE PANOCHE TWO IS OUTBOUND ON THE 301 DEG RADIAL. THERE WAS NO APPARENT ISSUE WITH THE ZOA CTLR, HE JUST CLRED US TO BORED INTXN FOR THE NEW ARR. WE ARE JUST EXPRESSING DOUBT OVER THE PREVIOUS CTLR'S POSSIBLE AMBIGUOUS PHRASEOLOGY. FMS EQUIPPED ACFT CAN SOMETIMES HAVE A NAV INTERFACE THAT IS NOT VERY TRANSPARENT TO THE CREW. COMBINE THIS WITH CTLR PHRASEOLOGY AND THE EXPECTATIONS OF THE FLT CREW TO FLY A FILED STAR THAT IS THE NORM AND 2 DIFFERENT STARS THAT SHARE A COMMON INITIAL FIX (PXN), IT IS EASY TO SEE THE POSSIBLE UNINTENDED CONSEQUENCES OF FLYING THE WRONG RADIAL. I RECOMMEND THAT WHEN CTLRS ISSUE UNEXPECTED CHANGES TO A STAR IN THIS FAST-PACED DYNAMIC ATC ENVIRONMENT, THAT THEY INCORPORATE THE WORD 'NOW' IN THE NEW CLRNC AS A CUE TO THE FLT CREWS THAT A CHANGE IS FORTHCOMING IN THE CLRNC. THEY SHOULD ALSO ADHERE TO STANDARD PHRASEOLOGY TO ELIMINATE AMBIGUITIES. AN EXAMPLE WOULD BE: 'YOU ARE NOW CLRED TO THE ABC ARPT VIA THE XYZ ARR.'

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.