B747 flight crew confuses a cleared via the BDEGA1 arrival as a clearance to descend via and starts ...

Attributes
ACN	1258981
Time
Date	201505
Place
Locale Reference	SFO.Airport
State Reference	CA
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Visual Approach STAR BDEGA ONE
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Experience	Flight Crew Last 90 Days 120 Flight Crew Total 20000 Flight Crew Type 500
Person 2
Function	First Officer
Experience	Flight Crew Last 90 Days 22 Flight Crew Total 12000 Flight Crew Type 200
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance

Narrative:

On bdega arrival a few miles prior to corkk. Cleared the '28L transition' and told to expect a visual to 28L. First officer (first officer) leveled at 11;000 feet to cross corkk at 11;000 feet; then requested 1;800 feet; in the altitude window; explaining that 'the 28L transition' meant we could descend further; apparently to get down so as to be ready for a short turn on to final. There was some discussion but then we went on to other things. Shortly after descending through 10;000 feet the controller questioned our altitude and then asked us to level off at 9;000 feet. He further explained that it was no problem this time; but for future reference 'cleared the 28L transition' meant to stay at 11;000 feet and fly the 140 course out of brixx.

Original NASA ASRS Text

Title: B747 flight crew confuses a cleared via the BDEGA1 arrival as a clearance to descend via and starts down after crossing CORKK at 11;000 feet. NCT detects the error.

Narrative: On BDEGA arrival a few miles prior to CORKK. Cleared the '28L transition' and told to expect a visual to 28L. First Officer (FO) leveled at 11;000 feet to cross CORKK at 11;000 feet; then requested 1;800 feet; in the altitude window; explaining that 'the 28L transition' meant we could descend further; apparently to get down so as to be ready for a short turn on to final. There was some discussion but then we went on to other things. Shortly after descending through 10;000 feet the controller questioned our altitude and then asked us to level off at 9;000 feet. He further explained that it was no problem this time; but for future reference 'cleared the 28L transition' meant to stay at 11;000 feet and fly the 140 course out of BRIXX.

Data retrieved from NASA's ASRS site 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.

B747 flight crew confuses a cleared via the BDEGA1 arrival as a clearance to descend via and starts down after crossing corkk at 11;000 feet. Nct detects the error.