Narrative:

Clearance was the LGA2/whetstone climb. We were held on the ramp for 10 minutes before being cleared to taxi; during that time; the crew reviewed a few times the departure procedure; and I memorized the routing: '180 degree heading until 2.5DME from lga; right turn to 040 degrees; maintain 5;000; speed not to exceed 210 KTS until on a 040 degree heading'. We started our initial turn to 180 degrees and ATC issued something that I don't recall; probably just a frequency change; I engaged the autopilot and maintained a 180 degree heading. ATC issued another instruction to climb to 10;000. We encountered slight wake turbulence from preceding aircraft; and for some reason; I just maintained a 180 heading until we were 6.0 from lga. All that I remember running through my head was 'fly heading of 180 degrees' (it wasn't ATC; it was my own thoughts). We were queried by ATC what our departure was; partner looked at me confused and I told him that the controller told us to maintain a 180 degree heading; when in fact ATC said 'climb and maintain 10;000'; without reference to any heading. My partner told ATC we were discussing things and had some confusion abut the heading; ATC issued a right turn and told us 'not to worry about it'. Fatigue is by far the mitigating circumstance; when we arrived in lga after a short fast-paced flight; I was feeling the effects of fatigue. I felt I could muddle through the passenger flight; but now realize that a high-stress ATC environment such as ny could magnify potential problems. I had 4 hours of sleep the night prior and about 6 hours the night before. Operating outside my normal sleep cycle mitigated the fatigue and led to the error. Also; enabling crews to maintain a sleep cycle that is normal to their circadian rhythm would help reduce errors.

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Original NASA ASRS Text

Title: Captain reported deviating from the LGA Whetstone Climb because of fatigue and a slight distraction due to wake turbulence.

Narrative: Clearance was the LGA2/Whetstone Climb. We were held on the ramp for 10 minutes before being cleared to taxi; during that time; the crew reviewed a few times the departure procedure; and I memorized the routing: '180 degree heading until 2.5DME from LGA; right turn to 040 degrees; maintain 5;000; speed not to exceed 210 KTS until on a 040 degree heading'. We started our initial turn to 180 degrees and ATC issued something that I don't recall; probably just a frequency change; I engaged the autopilot and maintained a 180 degree heading. ATC issued another instruction to climb to 10;000. We encountered slight wake turbulence from preceding aircraft; and for some reason; I just maintained a 180 heading until we were 6.0 from LGA. All that I remember running through my head was 'fly heading of 180 degrees' (it wasn't ATC; it was my own thoughts). We were queried by ATC what our departure was; partner looked at me confused and I told him that the Controller told us to maintain a 180 degree heading; when in fact ATC said 'climb and maintain 10;000'; without reference to any heading. My partner told ATC we were discussing things and had some confusion abut the heading; ATC issued a right turn and told us 'not to worry about it'. Fatigue is by far the mitigating circumstance; when we arrived in LGA after a short fast-paced flight; I was feeling the effects of fatigue. I felt I could muddle through the passenger flight; but now realize that a high-stress ATC environment such as NY could magnify potential problems. I had 4 hours of sleep the night prior and about 6 hours the night before. Operating outside my normal sleep cycle mitigated the fatigue and led to the error. Also; enabling crews to maintain a sleep cycle that is normal to their circadian rhythm would help reduce errors.

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.