Narrative:

Lax runway heading 25R shortly after takeoff, and following heavily loaded standard 747, we encountered heavy wake turbulence which mandated immediate evasive maneuver to avoid. I believe we were properly separated by lax tower, 5-6 mi. What is most interesting here is that the wake created a most disturbing lack of control at a most critical time in departure and, of course, it was invisible. I feel that a smaller aircraft than our 747-400 would have been subjected to far less ctlability. I ask that this data be recorded as potential loss of control. Perhaps our current separation is inadequate. Wind on takeoff was approximately 300/9 for our 25R departure runway. A night takeoff would have introduced 1 more negative element to this encounter.

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Original NASA ASRS Text

Title: A VERY HVY WDB ACFT EXPERIENCED WAKE TURB BEHIND ANOTHER VERY HVY WDB ACFT ON INITIAL CLB.

Narrative: LAX RWY HDG 25R SHORTLY AFTER TKOF, AND FOLLOWING HEAVILY LOADED STANDARD 747, WE ENCOUNTERED HVY WAKE TURB WHICH MANDATED IMMEDIATE EVASIVE MANEUVER TO AVOID. I BELIEVE WE WERE PROPERLY SEPARATED BY LAX TWR, 5-6 MI. WHAT IS MOST INTERESTING HERE IS THAT THE WAKE CREATED A MOST DISTURBING LACK OF CTL AT A MOST CRITICAL TIME IN DEP AND, OF COURSE, IT WAS INVISIBLE. I FEEL THAT A SMALLER ACFT THAN OUR 747-400 WOULD HAVE BEEN SUBJECTED TO FAR LESS CTLABILITY. I ASK THAT THIS DATA BE RECORDED AS POTENTIAL LOSS OF CTL. PERHAPS OUR CURRENT SEPARATION IS INADEQUATE. WIND ON TKOF WAS APPROX 300/9 FOR OUR 25R DEP RWY. A NIGHT TKOF WOULD HAVE INTRODUCED 1 MORE NEGATIVE ELEMENT TO THIS ENCOUNTER.

Data retrieved from NASA's ASRS site as of July 2007 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.