Date: 201401
Local time of day: 0601-1200
Location: SJC.Airport, CA
Flight conditions: Marginal
Weather elements / visibility: Rain
Light: Daylight
Aircraft: Citation Excel (C560XL)
Operator: Fractional
Operating under: Part 135
Flight plan: IFR
Flight phase: Initial Approach
Airspace: Class C SJC
ATC / advisory: Tower SJC
Aircraft component: Altitude Alert
Component problem: Improperly Operated
Reporter organization: Fractional
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Human-Machine Interface; Distraction; Confusion; Workload; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Air Traffic Control; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance
Contributing factors: Chart Or Publication; Human Factors
Primary problem: Human Factors

Narrative: During RNAV (GPS) Y Runway 30L approach got a low altitude call from Tower after HIVAK and before FORUL. Our alerter was set for 700 FT (incorrectly) for minimums after HIVAK. Fortunately; we were by this time VMC and were able to see the runway environment; but we were definitely too low. We got a terrain TCAS alert shortly before the Tower's low altitude call. Neither pilot caught the Number 2 ball note on the approach for the intermediate 1;480 foot altitude constraint at FORUL. We were both very distracted by an [earlier] Approach [Control] clearance to climb from 5;000 FT to 6;000 FT prior to KLIDE for conflicting traffic and were working to lose altitude by HIVAK to catch up to the profile. Although I believed I'd accomplished a very thorough brief during the Approach Checklist; missing the FORUL constraint was a huge error. I need to be more thorough in reviewing RNAV GPS Approaches. This could have been catastrophic! Although I briefed a comprehensive approach; I missed a most important aspect...And will need to be MUCH more vigilant with RNAV GPS approaches in the future.... That said; I believe the depiction and rendering of the RNAV (GPS) Y RWY 30L Approach profile view could be improved by giving more space between the 'fan' mark at FORUL and the '1' in the '1;480' altitude in the profile. When my eye caught the figure while briefing the approach it appeared to be a distraction rather than an important feature. GPS Approaches have evolved into near 'Precision' approaches for aircraft with systems that can utilize LPV; or LNAV/VNAV functions; and a precision descent path is depicted on nearly all RNAV (GPS) approaches with less emphasis now given to the true non-precision LNAV only portion of the approach. Prior to the evolution of these approaches into a more precision oriented approach; step down descents were routinely depicted in the profile view. Had a dashed step-down line been depicted to accompany the 1;480 FT level off been placed in the profile view; I think it would have been clearer and more helpful when flying equipment with LNAV only capability; and the '2' note would not have to change. This feature; given that the LNAV portion is a 'true non-precision' approach' would not detract from the 'precision' portion for those flying the more sophisticated equipment because the 'solid' descent line would still remain as the prominent feature of the profile. Both depictions are appropriate; and essential in this pilot's view.




Synopsis: While shooting the RNAV (GPS) Y Runway 30L approach to SJC the flight crew of a CE-560; equipped with only LNAV minima compliant avionics; failed to note the 1;480 MSL intermediate crossing restriction at FORUL for such aircraft. They had initiated a descent to the MDA (640 MSL) at the FAF and were issued a low altitude alert from the Tower prior to reaching FORUL.