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A B737 flight crew deviated from the charted SID when they were distracted by wake turbulence from the preceding aircraft.
| Attributes | |
| ACN | 741489 |
| Time | |
| Date | 200706 |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : las.airport |
| State Reference | NV |
| Altitude | agl single value : 600 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : l30.tracon tower : eddf.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | climbout : takeoff |
| Route In Use | departure sid : stavv 3 |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | tracon : l30.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | Airbus Industrie Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | climbout : takeoff |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Experience | flight time last 90 days : 163 |
| ASRS Report | 741489 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Experience | flight time last 90 days : 200 |
| ASRS Report | 741488 |
| Events | |
| Anomaly | inflight encounter : wake turbulence non adherence : clearance non adherence : published procedure other spatial deviation |
| Independent Detector | other controllera |
| Resolutory Action | controller : provided flight assist flight crew : returned to intended or assigned course |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance Environmental Factor |
| Primary Problem | Flight Crew Human Performance |
Narrative:
We were cleared for takeoff behind another carrier. Passing 400 ft I selected LNAV and subsequently encountered wake turbulence from the preceding other carrier requiring full aileron deflection to maintain wings level. Passing 1000 ft AGL I engaged the autopilot and due to the distraction of the continuing wake turbulence; I didn't notice the autopilot was in cws mode instead of LNAV. I started the turn approximately one half mile past leeln and while we were in the turn; departure called and advised us that we needed to turn immediately. We told him we were in the turn and reported the wake turbulence. He repeated that we needed to turn and that we should let him know if we needed to climb straight ahead. We didn't have time to explain to him the details of what happened and he put us on a vector and switched us to the next frequency. This incident underscores the importance of checking the 'scoreboard' to ensure you're in the correct mode. Las departure could consider increasing spacing when wind conditions are such that wake turbulence encounters are likely or assigning fan headings to intercept departures. My biggest error in this situation was probably that I diverted attention from our flight path while I attempted to engage the LNAV mode of the autopilot.
Original NASA ASRS Text
Title: A B737 FLT CREW DEVIATED FROM THE CHARTED SID WHEN THEY WERE DISTRACTED BY WAKE TURB FROM THE PRECEDING ACFT.
Narrative: WE WERE CLRED FOR TAKEOFF BEHIND ANOTHER CARRIER. PASSING 400 FT I SELECTED LNAV AND SUBSEQUENTLY ENCOUNTERED WAKE TURB FROM THE PRECEDING OTHER CARRIER REQUIRING FULL AILERON DEFLECTION TO MAINTAIN WINGS LEVEL. PASSING 1000 FT AGL I ENGAGED THE AUTOPILOT AND DUE TO THE DISTRACTION OF THE CONTINUING WAKE TURB; I DIDN'T NOTICE THE AUTOPILOT WAS IN CWS MODE INSTEAD OF LNAV. I STARTED THE TURN APPROX ONE HALF MILE PAST LEELN AND WHILE WE WERE IN THE TURN; DEP CALLED AND ADVISED US THAT WE NEEDED TO TURN IMMEDIATELY. WE TOLD HIM WE WERE IN THE TURN AND REPORTED THE WAKE TURB. HE REPEATED THAT WE NEEDED TO TURN AND THAT WE SHOULD LET HIM KNOW IF WE NEEDED TO CLB STRAIGHT AHEAD. WE DIDN'T HAVE TIME TO EXPLAIN TO HIM THE DETAILS OF WHAT HAPPENED AND HE PUT US ON A VECTOR AND SWITCHED US TO THE NEXT FREQUENCY. THIS INCIDENT UNDERSCORES THE IMPORTANCE OF CHECKING THE 'SCOREBOARD' TO ENSURE YOU'RE IN THE CORRECT MODE. LAS DEP COULD CONSIDER INCREASING SPACING WHEN WIND CONDITIONS ARE SUCH THAT WAKE TURB ENCOUNTERS ARE LIKELY OR ASSIGNING FAN HEADINGS TO INTERCEPT DEPS. MY BIGGEST ERROR IN THIS SITUATION WAS PROBABLY THAT I DIVERTED ATTENTION FROM OUR FLT PATH WHILE I ATTEMPTED TO ENGAGE THE LNAV MODE OF THE AUTOPILOT.
Data retrieved from NASA's ASRS site as of January 2009 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.