Narrative:

[I was] on my first long cross-country flight of the year. I was southbound on an airway approaching my next NAVAID and preparing to transition to another airway. I had been flying in actual IMC for over 2+ hours (but I did have a fuel stop about 1 hour before). I had the autopilot engaged flying the plane in climb; cruise and descent. I was getting very tired of the gray view out of the windshield and I asked center for a lower altitude. I was also in the process of studying my charts in preparation for the next leg of my trip and I was concentrating on flipping the pages of my chart book. I received a clearance from center for my first descent and to expect lower from approach. I descended and leveled off with the autopilot and went back to studying my charts. I then received a lower clearance from the TRACON; and when I looked at the altimeter I noticed that my autopilot had not held my last altitude exactly and that I was already about 300 ft below my last assigned altitude; so I programmed the autopilot to continue on down; and I went back to studying my charts. When I broke out into VFR (at about 9;500 ft) I picked my head up to look out and then I scanned the rest of my instruments. I then realized that my autopilot had turned me to an easterly heading (off of my southerly desired track). I instinctively throttled back to slow down; but then continued my descent normally and tried to figure out what was going wrong. At first I thought that I had failing dg and started thinking about covering it up. But first I fiddled with the obs and the heading bug; but there was no change in the autopilot and heading. When I started to level out at 8;000 ft; I checked my compass to confirm my heading; and it was easterly. By then I knew that I was well off of the centerline of the airway and I asked the controller for a vector back to the airway. I received one and began hand flying the plane back to the airway. As I was following the vector; I looked down and saw an airport directly under me. I decided it was a good time to land; regroup and refresh. I canceled IFR; got the CTAF for the airport from the controller and landed. When I looked at my charts after landing; I realized that I was about 17 NM off of the airway which I had filed for.human performance considerations: in hind sight; there were several factors that could have contributed to this event: 1) a long cold; cloudy and snowy winter in michigan really limited the amount of IFR flying I could do over the recent months. 2) as a relatively low hour IFR pilot; with only about 21 hours of actual IMC time (of which; this trip contributed 2.4 hours of actual) this was the longest time for me to be in continuous actual IMC conditions. 3) an 'over dependence' on the reliability of the autopilot for extended periods of time. 4) total flight time of over 4 hours; up to the time of this event was probably a bit fatiguing (even with a fuel stop about 1 hour earlier). 5) my inaction of properly scanning all instruments and systems on a regular basis and interval 6.) distractions of flipping forward and backward in my chart book; and being focused on these pages for an extended period of time; at the cost of my other responsibilities. Lessons learned from this event: 1) first and foremost -- do not relinquish my pilot in command responsibilities to the autopilot! 2) when feasible cruise in VFR conditions as much as possible in order to avoid the fatigue of the 'soup.' 3) to 'pre-tab' the pages of my chart books before the flight and/or have a list of the page sequences on my lap board. 4) scan; scan; scan the instruments and systems regularly. 5) if an instrument or autopilot seems to be acting funny; don't leave it alone until you have an understanding of what it is trying to 'tell' you. 6) maybe next winter; find someplace where I can get some simulator time in order to keep some of the rust off my IFR skills.

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Original NASA ASRS Text

Title: A C182 pilot; fatigued and distracted after flying two hours IMC; failed to notice his heading change while descending. Realizing he was seventeen miles off his filed airway; elected to divert to a nearby airport.

Narrative: [I was] on my first long cross-country flight of the year. I was southbound on an airway approaching my next NAVAID and preparing to transition to another airway. I had been flying in actual IMC for over 2+ hours (but I did have a fuel stop about 1 hour before). I had the autopilot engaged flying the plane in climb; cruise and descent. I was getting very tired of the gray view out of the windshield and I asked Center for a lower altitude. I was also in the process of studying my charts in preparation for the next leg of my trip and I was concentrating on flipping the pages of my chart book. I received a clearance from Center for my first descent and to expect lower from approach. I descended and leveled off with the autopilot and went back to studying my charts. I then received a lower clearance from the TRACON; and when I looked at the altimeter I noticed that my autopilot had not held my last altitude exactly and that I was already about 300 FT below my last assigned altitude; so I programmed the autopilot to continue on down; and I went back to studying my charts. When I broke out into VFR (at about 9;500 FT) I picked my head up to look out and then I scanned the rest of my instruments. I then realized that my autopilot had turned me to an easterly heading (off of my southerly desired track). I instinctively throttled back to slow down; but then continued my descent normally and tried to figure out what was going wrong. At first I thought that I had failing DG and started thinking about covering it up. But first I fiddled with the OBS and the heading bug; but there was no change in the autopilot and heading. When I started to level out at 8;000 FT; I checked my compass to confirm my heading; and it was easterly. By then I knew that I was well off of the centerline of the airway and I asked the Controller for a vector back to the airway. I received one and began hand flying the plane back to the airway. As I was following the vector; I looked down and saw an airport directly under me. I decided it was a good time to land; regroup and refresh. I canceled IFR; got the CTAF for the airport from the Controller and landed. When I looked at my charts after landing; I realized that I was about 17 NM off of the airway which I had filed for.Human performance considerations: in hind sight; there were several factors that could have contributed to this event: 1) a long cold; cloudy and snowy winter in Michigan really limited the amount of IFR flying I could do over the recent months. 2) As a relatively low hour IFR pilot; with only about 21 hours of actual IMC time (of which; this trip contributed 2.4 hours of actual) this was the longest time for me to be in continuous actual IMC conditions. 3) An 'over dependence' on the reliability of the autopilot for extended periods of time. 4) Total flight time of over 4 hours; up to the time of this event was probably a bit fatiguing (even with a fuel stop about 1 hour earlier). 5) My inaction of properly scanning all instruments and systems on a regular basis and interval 6.) Distractions of flipping forward and backward in my chart book; and being focused on these pages for an extended period of time; at the cost of my other responsibilities. Lessons learned from this event: 1) First and foremost -- do not relinquish my pilot in command responsibilities to the autopilot! 2) When feasible cruise in VFR conditions as much as possible in order to avoid the fatigue of the 'soup.' 3) To 'pre-tab' the pages of my chart books before the flight and/or have a list of the page sequences on my lap board. 4) SCAN; SCAN; SCAN the instruments and systems regularly. 5) If an instrument or autopilot seems to be acting funny; don't leave it alone until you have an understanding of what it is trying to 'tell' you. 6) Maybe next winter; find someplace where I can get some simulator time in order to keep some of the rust off my IFR skills.

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.