MD80 flight crew encounters wake turbulence during approach to lax.

Attributes
ACN	728450
Time
Date	200702
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : lax.airport
State Reference	CA
Altitude	msl bound lower : 2500 msl bound upper : 2900
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	tower : lax.tower
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : n/s
Flight Phase	descent : approach
Route In Use	approach : traffic pattern
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
Route In Use	approach : straight in
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	728450
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : wake turbulence
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : exited adverse environment flight crew : returned to assigned altitude flight crew : returned to intended or assigned course
Supplementary
Problem Areas	Environmental Factor
Primary Problem	Environmental Factor

Narrative:

Lax approach cleared us in behind an air carrier Y B747 and told us we would follow about 6 mi behind. We were cleared to 2500 ft MSL while on the downwind. The B77 was straight in and we were extended several miles downwind at 2500 ft MSL. As we were approaching glideslope intercept our distance behind the B747 was approximately 7 mi; we encountered their wake turbulence. After a couple of minor encounters we entered what felt like the main part of the wake. We applied full power and climbed to get out of the wake. I informed ATC we were deviating for wake turbulence. He asked which way; and I said 'up.' once we were clear of the turbulence; we resumed the approach. At this point we were slightly above the glideslope at approximately 2900 ft MSL. The remainder of the approach was uneventful.

Original NASA ASRS Text

Title: MD80 FLT CREW ENCOUNTERS WAKE TURB DURING APPROACH TO LAX.

Narrative: LAX APPROACH CLEARED US IN BEHIND AN ACR Y B747 AND TOLD US WE WOULD FOLLOW ABOUT 6 MI BEHIND. WE WERE CLEARED TO 2500 FT MSL WHILE ON THE DOWNWIND. THE B77 WAS STRAIGHT IN AND WE WERE EXTENDED SEVERAL MILES DOWNWIND AT 2500 FT MSL. AS WE WERE APPROACHING GLIDESLOPE INTERCEPT OUR DISTANCE BEHIND THE B747 WAS APPROX 7 MI; WE ENCOUNTERED THEIR WAKE TURB. AFTER A COUPLE OF MINOR ENCOUNTERS WE ENTERED WHAT FELT LIKE THE MAIN PART OF THE WAKE. WE APPLIED FULL POWER AND CLIMBED TO GET OUT OF THE WAKE. I INFORMED ATC WE WERE DEVIATING FOR WAKE TURB. HE ASKED WHICH WAY; AND I SAID 'UP.' ONCE WE WERE CLEAR OF THE TURB; WE RESUMED THE APPROACH. AT THIS POINT WE WERE SLIGHTLY ABOVE THE GLIDESLOPE AT APPROXIMATELY 2900 FT MSL. THE REMAINDER OF THE APPROACH WAS UNEVENTFUL.

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.