B737 Next Generation Undifferentiated
Flight Crew Air Transport Pilot (ATP)
Workload; Distraction; Confusion; Time Pressure
ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Chart Or Publication; Procedure
While approaching the TROXX waypoint on the SILCN 1 RNAV Arrival; Oakland Center cleared the flight via the SILCN 1 Arrival; maintain FL340. The flight was not cleared to descend via. Later; Oakland Center cleared the flight to descend Pilot Discretion FL240. The arrival was properly briefed and verified per the arrival chart and FMC. SILCN 1 RNAV has the SILCN waypoint at 280 knots; at or above FL200. The aircraft was engaged in VNAV/LNAV; with the autothrottle engaged and on path. Approximately 12 NM from SILCN; Oakland Center cleared the flight to cross SILCN at 280 knots; at FL200. The Pilot Flying entered the altitude restriction of FL200 into the FMC; verified and executed. The path was recalculated and was now showing 3800 feet high. Oakland Center was informed of this; and the Pilot Monitoring requested relief from the crossing restriction. Oakland Center stated to 'Do the best you can.' The speedbrake was full deployed; at approximately 15 NM prior to the VLLEY waypoint; the aircraft leveled off at FL200. The flight was switched to NorCal Approach; and one has to communicate quickly with them to continue the descent for future crossing restrictions. We were still not cleared to descend via the arrival. NorCal issued a clearance to descend via the SILCN 1; landing northwest. This clearance was issued at the Top of Descent for the FMC.Recommend changing the STAR for the crossing restriction at the SILCN waypoint to be at FL200 instead of at or above FL200. This may change the TROXX waypoint altitude crossing restriction as well. Recommend Oakland Center does not issue an altitude crossing restriction while 12 NM from the SICLN waypoint. This altitude restriction cannot be met when given an airspeed restriction for the arrival. If SILCN crossing restriction is always going to be FL200; this needs to be advised to the flight crews prior to the TROXX waypoint; and not while on the descent path.
[Report narrative contained no additional information.]
A B737-NG aircraft on the SJC SILCN 1 RNAV profile was cleared to cross the VLLEY waypoint at FL200 when the aircraft was 15 NM from that point. The crew told ATC unable.