Narrative:

Climbing out of las on runway 7R behind an airbus 320. Takeoff and climb were normal and LNAV engaged and verified at 400 ft. Autoplt selected at 1200 ft after first flap retraction. Climbing out of approximately 3500 ft we encountered moderate jetwash from the airbus that caused the aircraft to bank sharply to the right and subsequently disengage the LNAV. The aircraft deviated 15 degrees to a heading of 090 degrees. Runway heading was 075 degrees. The autoplt was immediately disengaged and corrective action was taken to turn the aircraft back to the original heading. During this course of action; ATC alerted us to a traffic conflict with a king air that had departed the parallel runway and were given a corrective heading of 060 degrees. We continued the turn until we reached the new heading. During this sequence we were climbing to an altitude of FL190 and were eventually given the phone number to call las TRACON. In reflection; corrective action was taken immediately and we did what we could; but it is very important to recognize this problem immediately because of the traffic separation issues at las. Supplemental information from acn 701859: cleared for takeoff behind another air carrier A320 on runway 7L at A8. King air was cleared for takeoff just prior to us on runway 7R. After takeoff; PF (first officer) engaged LNAV at 400 ft and then the autoplt at 1000 ft. Both pilots confirmed autoplt and LNAV engaged. I selected legs page on my FMC as PF called flaps 1 degree; climb thrust. Passing 3600-3800 ft; the aircraft encountered heavy jetwash from preceding aircraft with moderate wing rock which disengaged LNAV navigation and reverted to control wheel steering in a 10-20 degrees of right bank. The PF immediately disengaged autoplt and turned the aircraft back to the initial LNAV departure heading. Las TRACON called us at this time and told us we were off course and that we had king air traffic at our right 3 for a couple of mi and gave us a left turn to 060 degrees. We continued the departure and were told to contact las TRACON supervisor when we arrived. I contacted him after landing; told him what happened to us; and he told me that he needed to file a pilot deviation due to the close proximity of the king air to our aircraft since we were both under IFR control and had less than 3 mi separation.

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Original NASA ASRS Text

Title: A B 737-700 FLT CREW DEPARTING LAS BEHIND AN A320 ENCOUNTERED WAKE TURB THAT CAUSED THE ACFT TO DEVIATE R OF TRACK TOWARD A KING AIR.

Narrative: CLBING OUT OF LAS ON RWY 7R BEHIND AN AIRBUS 320. TKOF AND CLB WERE NORMAL AND LNAV ENGAGED AND VERIFIED AT 400 FT. AUTOPLT SELECTED AT 1200 FT AFTER FIRST FLAP RETRACTION. CLBING OUT OF APPROX 3500 FT WE ENCOUNTERED MODERATE JETWASH FROM THE AIRBUS THAT CAUSED THE ACFT TO BANK SHARPLY TO THE R AND SUBSEQUENTLY DISENGAGE THE LNAV. THE ACFT DEVIATED 15 DEGS TO A HDG OF 090 DEGS. RWY HDG WAS 075 DEGS. THE AUTOPLT WAS IMMEDIATELY DISENGAGED AND CORRECTIVE ACTION WAS TAKEN TO TURN THE ACFT BACK TO THE ORIGINAL HDG. DURING THIS COURSE OF ACTION; ATC ALERTED US TO A TFC CONFLICT WITH A KING AIR THAT HAD DEPARTED THE PARALLEL RWY AND WERE GIVEN A CORRECTIVE HDG OF 060 DEGS. WE CONTINUED THE TURN UNTIL WE REACHED THE NEW HDG. DURING THIS SEQUENCE WE WERE CLBING TO AN ALT OF FL190 AND WERE EVENTUALLY GIVEN THE PHONE NUMBER TO CALL LAS TRACON. IN REFLECTION; CORRECTIVE ACTION WAS TAKEN IMMEDIATELY AND WE DID WHAT WE COULD; BUT IT IS VERY IMPORTANT TO RECOGNIZE THIS PROB IMMEDIATELY BECAUSE OF THE TFC SEPARATION ISSUES AT LAS. SUPPLEMENTAL INFO FROM ACN 701859: CLRED FOR TKOF BEHIND ANOTHER ACR A320 ON RWY 7L AT A8. KING AIR WAS CLRED FOR TKOF JUST PRIOR TO US ON RWY 7R. AFTER TKOF; PF (FO) ENGAGED LNAV AT 400 FT AND THEN THE AUTOPLT AT 1000 FT. BOTH PLTS CONFIRMED AUTOPLT AND LNAV ENGAGED. I SELECTED LEGS PAGE ON MY FMC AS PF CALLED FLAPS 1 DEG; CLB THRUST. PASSING 3600-3800 FT; THE ACFT ENCOUNTERED HVY JETWASH FROM PRECEDING ACFT WITH MODERATE WING ROCK WHICH DISENGAGED LNAV NAV AND REVERTED TO CTL WHEEL STEERING IN A 10-20 DEGS OF R BANK. THE PF IMMEDIATELY DISENGAGED AUTOPLT AND TURNED THE ACFT BACK TO THE INITIAL LNAV DEP HDG. LAS TRACON CALLED US AT THIS TIME AND TOLD US WE WERE OFF COURSE AND THAT WE HAD KING AIR TFC AT OUR R 3 FOR A COUPLE OF MI AND GAVE US A L TURN TO 060 DEGS. WE CONTINUED THE DEP AND WERE TOLD TO CONTACT LAS TRACON SUPVR WHEN WE ARRIVED. I CONTACTED HIM AFTER LNDG; TOLD HIM WHAT HAPPENED TO US; AND HE TOLD ME THAT HE NEEDED TO FILE A PLTDEV DUE TO THE CLOSE PROX OF THE KING AIR TO OUR ACFT SINCE WE WERE BOTH UNDER IFR CTL AND HAD LESS THAN 3 MI SEPARATION.

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.