Large Transport
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 143; Flight Crew Total 12564; Flight Crew Type 10188
Situational Awareness; Communication Breakdown; Confusion
ATC Issue All Types; Airspace Violation All Types; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Flight Crew Exited Penetrated Airspace; Flight Crew Became Reoriented
Human Factors; Procedure; Airspace Structure; Chart Or Publication
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.
[Report narrative contained no additional information].
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.