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B737 on approach to runway 24R at lax has wake turbulence encounter from B747 cleared to pass across his approach path to land on runway 24L.
| Attributes | |
| ACN | 745660 |
| Time | |
| Date | 200707 |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : lax.airport |
| State Reference | CA |
| Altitude | msl single value : 200 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tower : lax.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : approach |
| Route In Use | approach : visual |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | tower : lax.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B747 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : approach |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 130 flight time total : 9000 flight time type : 2000 |
| ASRS Report | 745660 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Events | |
| Anomaly | inflight encounter : wake turbulence other anomaly |
| Independent Detector | other flight crewa other flight crewb |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance Environmental Factor ATC Human Performance |
| Primary Problem | Environmental Factor |
Narrative:
We were on approach to lax 24R on a visual approach. ATC crossed a cargo B747 across our final from north to south so they could land on 24L. At the time we were about 5 miles from them. The wind was 190/04. We did not encounter any wake until about 500 ft AGL and it was just light buffeting. At 200 ft the aircraft rolled quickly to the right about 10 degrees. The captain countered it with opposite control inputs stopping the roll. The aircraft then rolled quickly to the left about 8 degrees; again he stopped the roll with opposite control inputs. This spooked many passenger as we could hear several screams from the back. The flight attendants confirmed this when we spoke with them later. The rate of roll was greater than any I had experienced in the past. I'm sure that the light crosswind is what put the wake vortex right on our flight path. Had we been slightly lower or in the flare this could have caused a wing tip or engine cowl to come in contact with the ground. We could have prevented this by flying a DOT high on the GS to stay above the wake vortex. We could have discussed the effects of the crosswind when ATC first told us of his intent to cross the 747 and for us to follow it to the parallel runway.
Original NASA ASRS Text
Title: B737 ON APCH TO RWY 24R AT LAX HAS WAKE TURBULENCE ENCOUNTER FROM B747 CLEARED TO PASS ACROSS HIS APCH PATH TO LAND ON RWY 24L.
Narrative: WE WERE ON APCH TO LAX 24R ON A VISUAL APCH. ATC CROSSED A CARGO B747 ACROSS OUR FINAL FROM N TO S SO THEY COULD LAND ON 24L. AT THE TIME WE WERE ABOUT 5 MILES FROM THEM. THE WIND WAS 190/04. WE DID NOT ENCOUNTER ANY WAKE UNTIL ABOUT 500 FT AGL AND IT WAS JUST LIGHT BUFFETING. AT 200 FT THE ACFT ROLLED QUICKLY TO THE R ABOUT 10 DEGS. THE CAPT COUNTERED IT WITH OPPOSITE CTL INPUTS STOPPING THE ROLL. THE ACFT THEN ROLLED QUICKLY TO THE L ABOUT 8 DEGS; AGAIN HE STOPPED THE ROLL WITH OPPOSITE CTL INPUTS. THIS SPOOKED MANY PAX AS WE COULD HEAR SEVERAL SCREAMS FROM THE BACK. THE FLT ATTENDANTS CONFIRMED THIS WHEN WE SPOKE WITH THEM LATER. THE RATE OF ROLL WAS GREATER THAN ANY I HAD EXPERIENCED IN THE PAST. I'M SURE THAT THE LIGHT CROSSWIND IS WHAT PUT THE WAKE VORTEX RIGHT ON OUR FLIGHT PATH. HAD WE BEEN SLIGHTLY LOWER OR IN THE FLARE THIS COULD HAVE CAUSED A WING TIP OR ENGINE COWL TO COME IN CONTACT WITH THE GROUND. WE COULD HAVE PREVENTED THIS BY FLYING A DOT HIGH ON THE GS TO STAY ABOVE THE WAKE VORTEX. WE COULD HAVE DISCUSSED THE EFFECTS OF THE CROSSWIND WHEN ATC FIRST TOLD US OF HIS INTENT TO CROSS THE 747 AND FOR US TO FOLLOW IT TO THE PARALLEL RWY.
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.