Air carrier medium large transport altitude deviation overshot during descent into sfo.

Attributes
ACN	107565
Time
Date	198903
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sfo
State Reference	CA
Altitude	msl bound lower : 6000 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oak
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 8500 flight time type : 2000
ASRS Report	107565
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	non adherence : clearance other anomaly
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Operational Deviation

Narrative:

We were receiving vectors for the ILS to 19L at sfo. From 10000 MSL, we received a clearance to 6000 MSL, which we acknowledged by reading back the assigned altitude (6000). After leveling at 6000', the controller asked us what our altitude was then directed a climb to 7000', which he thought he had previously cleared us to. We were both certain that he had in fact cleared us to 6000' MSL. No conflict occurred and we were in VMC.

Original NASA ASRS Text

Title: ACR MLG ALT DEVIATION OVERSHOT DURING DESCENT INTO SFO.

Narrative: WE WERE RECEIVING VECTORS FOR THE ILS TO 19L AT SFO. FROM 10000 MSL, WE RECEIVED A CLRNC TO 6000 MSL, WHICH WE ACKNOWLEDGED BY READING BACK THE ASSIGNED ALT (6000). AFTER LEVELING AT 6000', THE CTLR ASKED US WHAT OUR ALT WAS THEN DIRECTED A CLB TO 7000', WHICH HE THOUGHT HE HAD PREVIOUSLY CLRED US TO. WE WERE BOTH CERTAIN THAT HE HAD IN FACT CLRED US TO 6000' MSL. NO CONFLICT OCCURRED AND WE WERE IN VMC.

Data retrieved from NASA's ASRS site as of August 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.