RV-6
Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 16; Flight Crew Total 2007; Flight Crew Type 1250
Confusion
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors
On an IFR clearance; talking to Seattle Center and flying vectors to the Runway 26 ILS approach at AST. Was vectored to final and cleared for the approach approximately 5 miles outside of ZINKY intersection; with an altitude restriction of 5000 or 5500 until established; I don't recall for certain. In any case I intercepted the localizer about that same time and began a descent. I glanced briefly at the chart and saw 4000 so I descended to that altitude; without realizing that the altitude I was looking at was for JUNSA which I had not yet reached; and in fact I was still outside ZINKY where the min. altitude is 4400. After a minute or two I noticed I was below the glideslope and not yet at ZINKY; so I climbed to 4400 at about the time I passed ZINKY; and began a normal descent on the glideslope. Cause was my complacency; thinking I know this approach; and not looking more closely at the chart.
RV6 pilot reported descending to 4;000 feet outside ZINKY on the ILS Runway 26 at AST before realizing his mistake and climbing up to 4;400 feet.