B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 371
Workload; Situational Awareness; Human-Machine Interface; Confusion; Communication Breakdown
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Requested ATC Assistance / Clarification; Flight Crew FLC Overrode Automation
Company Policy; Procedure; Chart Or Publication
While on descent on the SILCN1 RNAV Arrival; ATC informed us he thought we were coming in high. We rechecked our position/altitude and replied we showed that we were on the descent profile.  We were cleared to 'descend via; landing west;' but had no further instructions (e.g.; 'join the 30L Localizer.')On the SILCN1 RNAV Arrival; all points after VLLEY are 'At or Above.'  Since we don't close the arrival/approach discontinuity until cleared for the approach; the FMC thinks we're flying to KLIDE (on the arrival); then back to GILRO (on the approach); then again to KLIDE. ATC stated it this way: 'Company builds in an extra 20 miles;' which would be alleviated if (1) we had queried their intended follow-on clearance; or (2) ATC gave us 'join 30L Localizer' early in the process.
We were cleared to descend via the SILCN1 RNAV Arrival into SJC; landing north after comparing FMS and Jeppesen Plate. We selected 4000 feet in the control panel and verified VNAV was selected. We met the restrictions at SILCN and VLLEY; but after crossing VLLEY Approach called and asked us if we were going to make the descent. We thought we would; but he said we were 3000 feet high. He also said that Company always puts in an extra 20 miles into the arrival and keeps us high.All of the crossing restrictions from there were 'At or Above'; so we didn't violate any altitudes; but after checking our distance to the runway; we agreed that we needed a vector to lose the altitude. We got back on path and landed uneventfully.Close the discontinuity in our flight plan on our own; or ask ATC earlier for a clearance past our present limit.
A B737 on the SJC SILCN1 RNAV appeared high on profile to NCT but the crew explained late ATC clearance to 'join the 30L Localizer' prevents the FMS from calculating distances correctly. The FMC calculates the altitude to KLIDE; back to GILRO and the return to KLIDE and causes a high approach. Crew managed the error manually.