An air carrier crew flying the sfo serfr one RNAV STAR were cleared; prior to epick; to 'descend via...

Attributes
ACN	1291263
Time
Date	201508
Local Time Of Day	1801-2400
Place
Locale Reference	NCT.TRACON
State Reference	CA
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR SERFR1
Flight Plan	IFR
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 143 Flight Crew Total 12564 Flight Crew Type 10188
Person 2
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 68 Flight Crew Total 25450 Flight Crew Type 566
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance Deviation - Procedural FAR Deviation - Speed All Types

Narrative:

We were assigned the SERFR1 STAR into sfo and cleared to 'descend via'; we entered the bottom altitude (4;000 feet) into the FCU and started a VNAV/managed airspeed descent; we complied with all altitude and airspeed restrictions on the STAR. Approaching epick the approach controller changed the clearance to 'descend via the SERFR1; except after epick descend and maintain 6;000 feet'. We crossed epick at 10;000 feet; slowed to 250 KTS; and then pulled for open descent to comply with the clearance. Approaching eddyy we slowed down to 240 KTS to comply with crossing airspeed and continued to descend through 7;000 feet for 6;000 feet. The approach controller advised we would descent below class B airspace and would reenter in 4 miles. The floor of the class B airspace is at 8;000 feet until 3 miles before eddyy; where it changes to 6;000 feet.when the controller issued the 'descend via; except' clearance; we are required to comply with the STAR speed restrictions (240 KTS at eddyy). The clearance to descend to 6;000 feet after epick is what put the aircraft below the floor of class B airspace. This puts the speed restriction at epick and the speed restriction below class B airspace in conflict. A more appropriate clearance would be 'descend via the SERFR1; except maintain 6;000 feet. Comply with altitude and airspeed at eddyy.'the design of the SERFR1 also conflicts with class B airspeed requirements. If the aircraft is early reaching 6;000 feet; the 240 KTS airspeed at eddyy will conflict every time.

Original NASA ASRS Text

Title: An air carrier crew flying the SFO SERFR ONE RNAV STAR were cleared; prior to EPICK; to 'Descend via the SERFR ONE; except after EPICK descend and maintain 6;000.' That clearance took the aircraft below Class B at 250 knots.

Narrative: We were assigned the SERFR1 STAR into SFO and cleared to 'descend via'; we entered the bottom altitude (4;000 feet) into the FCU and started a VNAV/managed airspeed descent; we complied with all altitude and airspeed restrictions on the STAR. Approaching EPICK the approach controller changed the clearance to 'descend via the SERFR1; except after EPICK descend and maintain 6;000 feet'. We crossed EPICK at 10;000 feet; slowed to 250 KTS; and then pulled for open descent to comply with the clearance. Approaching EDDYY we slowed down to 240 KTS to comply with crossing airspeed and continued to descend through 7;000 feet for 6;000 feet. The approach controller advised we would descent below Class B airspace and would reenter in 4 miles. The floor of the Class B airspace is at 8;000 feet until 3 miles before EDDYY; where it changes to 6;000 feet.When the controller issued the 'descend via; except' clearance; we are required to comply with the STAR speed restrictions (240 KTS at EDDYY). The clearance to descend to 6;000 feet after EPICK is what put the aircraft below the floor of Class B airspace. This puts the speed restriction at EPICK and the speed restriction below Class B airspace in conflict. A more appropriate clearance would be 'descend via the SERFR1; except maintain 6;000 feet. Comply with altitude and airspeed at EDDYY.'The design of the SERFR1 also conflicts with Class B airspeed requirements. If the aircraft is early reaching 6;000 feet; the 240 KTS airspeed at EDDYY will conflict every time.

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.

An air carrier crew flying the sfo serfr one RNAV STAR were cleared; prior to epick; to 'descend via the serfr one; except after epick descend and maintain 6;000.' that clearance took the aircraft below class B at 250 knots.