Narrative:

While doing a visual approach to runway 25L at lax, we were in trail of B747-400 by 5 NM. As we reached about 150 ft, encountered wake turbulence causing destabilized approach, wings rocked to about 15 degrees. Executed missed approach to a normal landing. Callback conversation with reporter revealed the following information: the captain was flying a B737-500 and admits that he knew about the B747-400 in front of them, but cannot recall if a controller told him about that aircraft. He said that although he has thought about the event a great deal he does not know why he stayed on the GS even though he knows about the effects of wake turbulence and its potential for disaster. The degree of bank was not the significant effect in this case, he said. It was the rapidity of the several roll movements that surprised the crew. In approximately 5 seconds the aircraft rolled left and right several times very violently, but as soon as they initiated a climb the wake effect ended.

Related reports:

Google
 

Original NASA ASRS Text

Title: A B737 ACR FLC HIT THE WAKE OF A B747 ON SHORT FINAL APCH. THE CAPT ADMITS THAT THE CONDITIONS WERE PERFECT FOR WAKE DEVELOPMENT, BUT HE FLEW THE GS 5 MI IN TRAIL ANYWAY. HE MADE A SUCCESSFUL GAR.

Narrative: WHILE DOING A VISUAL APCH TO RWY 25L AT LAX, WE WERE IN TRAIL OF B747-400 BY 5 NM. AS WE REACHED ABOUT 150 FT, ENCOUNTERED WAKE TURB CAUSING DESTABILIZED APCH, WINGS ROCKED TO ABOUT 15 DEGS. EXECUTED MISSED APCH TO A NORMAL LNDG. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CAPT WAS FLYING A B737-500 AND ADMITS THAT HE KNEW ABOUT THE B747-400 IN FRONT OF THEM, BUT CANNOT RECALL IF A CTLR TOLD HIM ABOUT THAT ACFT. HE SAID THAT ALTHOUGH HE HAS THOUGHT ABOUT THE EVENT A GREAT DEAL HE DOES NOT KNOW WHY HE STAYED ON THE GS EVEN THOUGH HE KNOWS ABOUT THE EFFECTS OF WAKE TURB AND ITS POTENTIAL FOR DISASTER. THE DEGREE OF BANK WAS NOT THE SIGNIFICANT EFFECT IN THIS CASE, HE SAID. IT WAS THE RAPIDITY OF THE SEVERAL ROLL MOVEMENTS THAT SURPRISED THE CREW. IN APPROX 5 SECONDS THE ACFT ROLLED L AND R SEVERAL TIMES VERY VIOLENTLY, BUT AS SOON AS THEY INITIATED A CLB THE WAKE EFFECT ENDED.

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.