Narrative:

Flight was about an hour behind schedule. Maintenance was in cockpit during cockpit preparation clearing previous MEL. No pre departure clearance available. Received verbal clearance. Clearance was BXK2 pmd as filed. Dispatch release indicated 'non-standard route.' BXK2 was entered into the FMC; confirmed; and briefed. BXK2 was filed and understood. Pilot not flying had chilly departure hanging on yoke clip. Captain was pilot not flying; first officer was pilot flying. Normal through takeoff and climb. Moderate wake turbulence from preceding aircraft was encountered during climb out and departure. Near 4 DME a turn to the north was made. After turning pilot flying realized that the BXK2 required a right turn to the south and began to turn right. At this time ATC queried our turn to the north and departure. Some discrepancy arose and ATC then issued a turn direct to zeper. Zeper was entered manually into the FMC as it is not on the BXK2. A frequency change was issued and the next controller indicated there may have been some discrepancy with our routing. He then issued new routing and gave us a phone number to call. Ensure proper departure is flown and ensure proper departure is displayed in front of the pilot flying.supplemental info from acn 824408: near 4 DME and prior to turning 100 degree heading on bxk departure. Pilot flying turned aircraft slightly left. Pilot not flying assumed another movement to displace aircraft for wake turbulence. I failed to query turn to north assuming it was an aircraft displacement for wake turbulence. While handling pilot not flying duties and assuring safe separation and aircraft control; I questioned myself with what I thought was the proper clearance.

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Original NASA ASRS Text

Title: B737-300 on departure encounters wake turbulence from the preceding aircraft. Subsequent to the initial wake event; the pilot flying deviated from the SID and the pilot not flying incorrectly assumes it is a wake avoidance maneuver.

Narrative: Flight was about an hour behind schedule. Maintenance was in cockpit during cockpit preparation clearing previous MEL. No PDC available. Received verbal clearance. Clearance was BXK2 PMD as filed. Dispatch release indicated 'NON-STANDARD ROUTE.' BXK2 was entered into the FMC; confirmed; and briefed. BXK2 was filed and understood. Pilot not flying had CHILLY departure hanging on yoke clip. Captain was pilot not flying; First Officer was pilot flying. Normal through takeoff and climb. Moderate wake turbulence from preceding aircraft was encountered during climb out and departure. Near 4 DME a turn to the north was made. After turning pilot flying realized that the BXK2 required a right turn to the south and began to turn right. At this time ATC queried our turn to the north and departure. Some discrepancy arose and ATC then issued a turn direct to ZEPER. ZEPER was entered manually into the FMC as it is not on the BXK2. A frequency change was issued and the next Controller indicated there may have been some discrepancy with our routing. He then issued new routing and gave us a phone number to call. Ensure proper departure is flown and ensure proper departure is displayed in front of the pilot flying.Supplemental info from ACN 824408: Near 4 DME and prior to turning 100 degree heading on BXK departure. Pilot flying turned aircraft slightly left. Pilot not flying assumed another movement to displace aircraft for wake turbulence. I failed to query turn to north assuming it was an aircraft displacement for wake turbulence. While handling pilot not flying duties and assuring safe separation and aircraft control; I questioned myself with what I thought was the proper clearance.

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.