B737 encounters confusion with ATC descent clearance into oak.

Attributes
ACN	578542
Time
Date	200304
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	intersection : catty
State Reference	CA
Altitude	msl bound lower : 9600 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : nct.tracon
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 230 flight time total : 6195 flight time type : 2756
ASRS Report	578542
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 141 flight time total : 22000 flight time type : 17000
ASRS Report	578543
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : returned to assigned altitude
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance

Narrative:

During the marvn 1 arrival into oak we had clearance to cross volta at 13000 ft. Before crossing volta norcal approach cleared us 'after volta direct catty, cross 28 mi east of catty at 8000 ft.' I loaded the clearance into the FMC to determine our descent profile. We needed to hurry down as we only had 12 mi to lose 5000 ft. At that point, the captain went off communication #1 to tell the flight attendants to secure the cabin. I was slowing to 250 KTS and began descending through 10000 ft. At around 9600 ft, the controller casually stated 'company number, I need you at 10000 ft.' I responded 'roger, 10000 ft, company number.' I then asked 'is that a new clearance rather than the 28 mi east of catty at 8000 ft?' the controller responded 'my apologies if that's what I gave you earlier. I need you at 10000 ft.' later, the controller said 'my apologies company, now cross catty at 8000 ft and contact norcal on XXX.X.' the rest of the flight was uneventful. The captain and I both believe this to be a simple case of an ATC misspoken clearance and was resolved without any conflicts or problems.

Original NASA ASRS Text

Title: B737 ENCOUNTERS CONFUSION WITH ATC DSCNT CLRNC INTO OAK.

Narrative: DURING THE MARVN 1 ARR INTO OAK WE HAD CLRNC TO CROSS VOLTA AT 13000 FT. BEFORE XING VOLTA NORCAL APCH CLRED US 'AFTER VOLTA DIRECT CATTY, CROSS 28 MI E OF CATTY AT 8000 FT.' I LOADED THE CLRNC INTO THE FMC TO DETERMINE OUR DSCNT PROFILE. WE NEEDED TO HURRY DOWN AS WE ONLY HAD 12 MI TO LOSE 5000 FT. AT THAT POINT, THE CAPT WENT OFF COM #1 TO TELL THE FLT ATTENDANTS TO SECURE THE CABIN. I WAS SLOWING TO 250 KTS AND BEGAN DSNDING THROUGH 10000 FT. AT AROUND 9600 FT, THE CTLR CASUALLY STATED 'COMPANY NUMBER, I NEED YOU AT 10000 FT.' I RESPONDED 'ROGER, 10000 FT, COMPANY NUMBER.' I THEN ASKED 'IS THAT A NEW CLRNC RATHER THAN THE 28 MI E OF CATTY AT 8000 FT?' THE CTLR RESPONDED 'MY APOLOGIES IF THAT'S WHAT I GAVE YOU EARLIER. I NEED YOU AT 10000 FT.' LATER, THE CTLR SAID 'MY APOLOGIES COMPANY, NOW CROSS CATTY AT 8000 FT AND CONTACT NORCAL ON XXX.X.' THE REST OF THE FLT WAS UNEVENTFUL. THE CAPT AND I BOTH BELIEVE THIS TO BE A SIMPLE CASE OF AN ATC MISSPOKEN CLRNC AND WAS RESOLVED WITHOUT ANY CONFLICTS OR PROBS.

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.