Narrative:

On climb out; we were given a heading; and then issued direct to mxe VOR. First officer was flying and I entered into FMC direct to mxe; however; as pilot not flying; I did not double check first officer selecting navigation in MCP. (First officer remained in heading select). Washington center asked if we were going direct mxe as we were already 10 miles off. [We] proceeded to mxe. The fatigue factor: we both had made numerous comments concerning our level of fatigue prior to this flight. The van driver had even asked me if I was sick due to my lethargic pace delivering load plan down the stairs to load master. This was our first night out for the week and this trip extended beyond the normal hours we are accustomed to flying. We both had made several small mistakes prior to this event. I have found (after 24 years) it is impossible to adjust your body and sleep patterns to varying schedules; especially when these schedules extend beyond normal arrival times; as is usually the case with re-routes; extra sections or other contributing factors. Flipping day/night schedules nearly always results in an extended period of being awake which contributes to a level of fatigue during any adjusted duty period. I am certainly not trying to make excuses for my error in not double checking the first officer; however; I can clearly speak on behalf of the first officer and I that our level of awareness was greatly diminished by the fatigue we were experiencing.

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Original NASA ASRS Text

Title: Air Carrier Captain describes a track deviation that occurs after being cleared direct and entering direct in the FMC but not selecting NAV on the MCP. Fatigue is reported to be a significant factor.

Narrative: On climb out; we were given a heading; and then issued direct to MXE VOR. First Officer was flying and I entered into FMC direct to MXE; however; as pilot not flying; I did not double check First Officer selecting NAV in MCP. (First Officer remained in Heading select). Washington Center asked if we were going direct MXE as we were already 10 miles off. [We] proceeded to MXE. The fatigue factor: We both had made numerous comments concerning our level of fatigue prior to this flight. The van driver had even asked me if I was sick due to my lethargic pace delivering load plan down the stairs to load master. This was our first night out for the week and this trip extended beyond the normal hours we are accustomed to flying. We both had made several small mistakes prior to this event. I have found (after 24 years) It is impossible to adjust your body and sleep patterns to varying schedules; especially when these schedules extend beyond normal arrival times; as is usually the case with re-routes; extra sections or other contributing factors. Flipping day/night schedules nearly always results in an extended period of being awake which contributes to a level of fatigue during any adjusted duty period. I am certainly not trying to make excuses for my error in not double checking the First Officer; however; I can clearly speak on behalf of the First Officer and I that our level of awareness was greatly diminished by the fatigue we were experiencing.

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.