Narrative:

We were at aun waiting for the weather to clear as forecast so we could continue on. When it looked for sure like that wasn't going to happen; I called the FSS to file an IFR-VFR on top and get a briefing for the flight back to the bay area. The ceiling was marginal - up and down with showers but nicer in the valley to the west (less than 10 miles away). Finally the rain had passed and when taxiing out and receiving the ASOS 'XA30Z automatic 12004KT 10SM FEW016 BKN028 OVC036' - and looking at the planes in the pattern I thought I didn't need that clearance. From the run up area of runway 25 you could easily see into the sacramento valley under the clouds and the planes in the pattern looked like they had gobs of cloud clearance. So I passed on the IFR clearance even though we were not in a hurry; took off and visually made the 20 degree (noise abatement) left turn at the end of the runway and proceeded to climb. At about 500-600 ft AGL I noticed that I was too far left on my heading so turned back to 230 thinking that my heading must have drifted without me noticing it. As I was soon to find out it was the slaved compass that was off and not me. So there I was; climbing out on runway heading below the cloud deck close to the inbound course of the GPS07-aun approach. At about 700 ft MSL I noticed that 2;800 ft ceiling didn't look so good ahead so I reduced power and rate of climb from 1200 FPM to a minimal amount - I had been distracted by the compass problem up to this point. There was descending valley below but a ridge on the other side and then the sacramento valley; the clouds seemed at their lowest height just over the ridge. I thought I could climb to a point where I'd get my 500 ft of clearance below the clouds and 1000 ft of clearance above the ground. It didn't work out as well as I wanted; in retrospect I think I was less than 500 ft below the clouds but fine regarding the ground. Also in retrospect; I could have legally flown lower over the ridge and been just fine as there were so few houses down there - this would have been safer in light of the fact that I was near the GPS approach course. When I thought about it later and looked at that instrument approach for runway 25 and the MDA was 1980 ft or 2200 ft if you were circling. I was above both altitudes near the FAF but don't know if I was on the course or not. If an inbound IFR pilot did not make calls on CTAF; I would not have known there was someone on approach. This was not good judgment. Contributing factors: a chain of events. The biggest problem was unrealized fatigue from way too much computer programming which really can spin you in - this was a relaxation day for me and my flying was not up to par. This is not like simple flying fatigue or lack of sleep - its very introverting for me. A very good ASOS report coupled with a misjudgment of distance - the ridge was much closer than it looked and hence the gap between the cloud layer and the ground was smaller than it looked. The time killed attending to the compass problem gave me less options when I finally looked ahead long enough to evaluate the situation. Relative unfamiliarity with the local auburn geography. Possibly the fact that my friend in the right seat seemed to be impatient contributed to this. Future corrective actions: just take that IFR clearance - the freezing level was above 4000 feet and that departure from aun has you at 3000 feet; plus it was nice about 10 miles west where I could have canceled; plus it's what I normally do. Check the compass against the runway heading; something I have done for years in IFR flying but it wouldn't be a bad idea for VFR either - it turns out that the HSI is going to need to be repaired. I could also have asked if anyone was on the approach when announced my takeoff. And the big one: if I am going to fly make sure I don't do too much programming the day before; especially late into the night as I did the night before.

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Original NASA ASRS Text

Title: General aviation pilot departing AUN reported a possible cloud clearance violation when he/she departed VFR and had difficultly remaining VFR; reporter listing fatigue; aircraft equipment malfunctions and local area unfamiliarity as some causal factors.

Narrative: We were at AUN waiting for the weather to clear as forecast so we could continue on. When it looked for sure like that wasn't going to happen; I called the FSS to file an IFR-VFR on top and get a briefing for the flight back to the Bay Area. The ceiling was marginal - up and down with showers but nicer in the Valley to the West (less than 10 miles away). Finally the rain had passed and when taxiing out and receiving the ASOS 'XA30Z AUTO 12004KT 10SM FEW016 BKN028 OVC036' - and looking at the planes in the pattern I thought I didn't need that clearance. From the run up area of Runway 25 you could easily see into the Sacramento Valley under the clouds and the planes in the pattern looked like they had gobs of cloud clearance. So I passed on the IFR clearance even though we were not in a hurry; took off and visually made the 20 degree (noise abatement) left turn at the end of the runway and proceeded to climb. At about 500-600 FT AGL I noticed that I was too far left on my heading so turned back to 230 thinking that my heading must have drifted without me noticing it. As I was soon to find out it was the slaved compass that was off and not me. So there I was; climbing out on runway heading below the cloud deck close to the inbound course of the GPS07-AUN approach. At about 700 FT MSL I noticed that 2;800 FT ceiling didn't look so good ahead so I reduced power and rate of climb from 1200 FPM to a minimal amount - I had been distracted by the compass problem up to this point. There was descending valley below but a ridge on the other side and then the Sacramento Valley; the clouds seemed at their lowest height just over the ridge. I thought I could climb to a point where I'd get my 500 FT of clearance below the clouds and 1000 FT of clearance above the ground. It didn't work out as well as I wanted; in retrospect I think I was less than 500 FT below the clouds but fine regarding the ground. Also in retrospect; I could have legally flown lower over the ridge and been just fine as there were so few houses down there - this would have been safer in light of the fact that I was near the GPS approach course. When I thought about it later and looked at that instrument approach for Runway 25 and the MDA was 1980 FT or 2200 FT if you were circling. I was above both altitudes near the FAF but don't know if I was on the course or not. If an inbound IFR pilot did not make calls on CTAF; I would not have known there was someone on approach. This was not good judgment. Contributing factors: A chain of events. The biggest problem was unrealized fatigue from way too much computer programming which really can spin you in - this was a relaxation day for me and my flying was not up to par. This is not like simple flying fatigue or lack of sleep - its very introverting for me. A very good ASOS report coupled with a misjudgment of distance - the ridge was much closer than it looked and hence the gap between the cloud layer and the ground was smaller than it looked. The time killed attending to the compass problem gave me less options when I finally looked ahead long enough to evaluate the situation. Relative unfamiliarity with the local Auburn geography. Possibly the fact that my friend in the right seat seemed to be impatient contributed to this. Future corrective actions: Just take that IFR clearance - the freezing level was above 4000 feet and that departure from AUN has you at 3000 feet; plus it was nice about 10 miles West where I could have canceled; plus it's what I normally do. Check the compass against the runway heading; something I have done for years in IFR flying but it wouldn't be a bad idea for VFR either - it turns out that the HSI is going to need to be repaired. I could also have asked if anyone was on the approach when announced my takeoff. And the big one: If I am going to fly make sure I don't do too much programming the day before; especially late into the night as I did the night before.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.