A B737 captain flying the sfo SERFR2 was cleared descend via except maintain 6;000 feet and then nor...

Narrative:

We were initially cleared to descend via the SERFR2 arrival to sfo. Our next clearance was to descend via the SERFR2; except maintain 10;000 feet. Our next clearance was to descend via; except maintain 6;000 feet. The controller then advised that we were leaving class B airspace and would re-enter in one mile; and they switched us to a new frequency. The new controller cleared us SERFR2 to the tipp toe visual 28L and cross menlo at or above 4;000 feet. Our next clearance was to cancel the tipp toe visual and we were given a heading to intercept the 28L localizer and maintain 3;100 feet.after intercepting the localizer we asked if we were cleared for the approach because we were held at 3;100 feet and we were intercepting our glidepath; approach said yes and passed us to tower. After contacting tower; our approach was canceled to 28L and we were subsequently cleared for a visual 28R. All of this took place within about 40 miles from the airport. This was a lot to handle in a short period of time and my first officer and I discussed whether we had done something wrong to get this many changes. After continued discussion with the first officer and our ATC specialist; we felt that we complied with all instructions; but there is room for improvement with ATC and descend via clearances with so many changes.

Original NASA ASRS Text

Title: A B737 Captain flying the SFO SERFR2 was cleared descend via except maintain 6;000 feet and then NORCAL alerted they descended out of SFO Class B. Numerous altitude clearance changes on the arrival created a high workload environment.

Narrative: We were initially cleared to descend via the SERFR2 Arrival to SFO. Our next clearance was to descend via the SERFR2; except maintain 10;000 feet. Our next clearance was to descend via; except maintain 6;000 feet. The Controller then advised that we were leaving Class B airspace and would re-enter in one mile; and they switched us to a new frequency. The new Controller cleared us SERFR2 to the TIPP TOE Visual 28L and cross MENLO at or above 4;000 feet. Our next clearance was to cancel the TIPP TOE visual and we were given a heading to intercept the 28L LOC and maintain 3;100 feet.After intercepting the LOC we asked if we were cleared for the approach because we were held at 3;100 feet and we were intercepting our glidepath; Approach said yes and passed us to Tower. After contacting Tower; our approach was canceled to 28L and we were subsequently cleared for a visual 28R. All of this took place within about 40 miles from the airport. This was a lot to handle in a short period of time and my FO and I discussed whether we had done something wrong to get this many changes. After continued discussion with the FO and our ATC Specialist; we felt that we complied with all instructions; but there is room for improvement with ATC and descend via clearances with so many changes.

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.

Attributes
ACN	1336683
Time
Date	201603
Local Time Of Day	0601-1200
Place
Locale Reference	SFO.Airport
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	STAR SERFR2
Flight Plan	IFR
Person 1
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 159
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Deviation - Procedural Published Material / Policy

A B737 captain flying the sfo SERFR2 was cleared descend via except maintain 6;000 feet and then norcal alerted they descended out of sfo class B. Numerous altitude clearance changes on the arrival created a high workload environment.