Date: 201503
Local time of day: 0601-1200
Location: PAO.Airport, CA
Flight conditions: IMC
Weather elements / visibility: Cloudy; 10
Light: Daylight
Aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Final Approach
Airspace: Class C SJC; Class D PAO
ATC / advisory: TRACON NCT
Reporter organization: Personal
Reporter function: Captain; Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Instrument; Flight Crew Commercial
Human factors: Communication Breakdown; Confusion; Distraction; Situational Awareness; Workload
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Contributing factors: Procedure; Human Factors; Weather
Primary problem: Procedure

Narrative: After multiple vectors by Norcal Approach in the vicinity of the SJC VOR; I was cleared for the VOR/DME approach to PAO. I elected to join the approach; with ATC approval; just west of the VOR. When I lined up on the segment of the approach between SJC and 5 DME west of SJC; I thought I was considerably further west than I was; and considerably higher than I needed to be. I then commenced a brisk descent. Rather than levelling off at the segment altitude of 1;700 feet; I continued my descent to 1;100 feet and broke out of the clouds in the vicinity of NUQ. At this point; I received an altitude alert from the tower advising me to check altitude immediately and climb. As I was in visual conditions and could clearly see PAO; I advised the tower that I wanted to continue on a visual approach (rather than climb back into the clouds). I then made the mistake of answering in the affirmative when the tower controller asked if I wished to cancel IFR. This was not my intention; as I did not have the necessary vertical separation from the cloud bases in class C or D airspace for flight under VFR. Had I not been in visual conditions; this could have been a very hazardous situation. However; as I had excellent visibility to the field; and was about 1;000 feet above any nearby obstructions; I felt that it was safer for me to remain visual rather than climb back into the clouds.I believe the problem started when I was denied entry to the VOR/DME approach via the published holding pattern. Instead; I was vectored away from the approach. Had I been cleared for one turn in the hold; I could have set up a stabilized approach and not been confused about position and altitude. Also; I should have initiated the approach at the VOR; rather than the intermediate approach segment. Finally; I should have requested a special VFR clearance in order to remain in visual conditions.Additional factors were my desire to land at PAO as soon as possible because of a breakfast meeting and the Norcal Approach controller's statement that she was holding traffic at SJC for me in order to complete the approach. One other factor was my previous experience using the GPS approach into PAO. While this approach was designed to avoid traffic conflicts with SJC; I have had approach clearances cancelled and been vectored far off course while attempting to use the GPS 31 approach. I thought that; like the last time I flew the VOR/DME approach; there would be light enough traffic at SJC in order to receive clearance for the full approach with hold into PAO.




Synopsis: A Pilot flying the PAO VOR/DME 31 got low on the approach and remained VMC; clear of obstacles even with an ATC low altitude alert and climb request.