MD90 crew encountered wake turbulence in trail of a B747 at sfo.

Attributes
ACN	476564
Time
Date	200006
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : sfo.airport
State Reference	CA
Altitude	msl single value : 3800
Environment
Light	Night
Aircraft 1
Controlling Facilities	tracon : o90.tracon tracon : p80.tracon
Operator	common carrier : air carrier
Make Model Name	MD-90 Series (DC-9-90) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 28l other
Flight Phase	descent : approach
Route In Use	arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : o90.tracon
Operator	common carrier : air carrier
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 28l
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	746564
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	inflight encounter : wake turbulence non adherence : published procedure
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : exited adverse environment
Supplementary
Problem Areas	Weather Flight Crew Human Performance Airspace Structure ATC Human Performance
Primary Problem	Ambiguous

Narrative:

B747 wake turbulence. Vectored to ILS final runway 28L behind a B747. On GS on a 12 mi final (altitude 3800 ft MSL) for runway 28L, aircraft entered a 15 degree roll left and immediately corrected to the right with pilot input. 2 more oscillations occurred associated with a noticeable sink rate. The period of this event lasted 3-4 seconds. After power was added aircraft exited wake from B747 5 mi ahead. Approach was continued with descent above GS and was uneventful through landing.

Original NASA ASRS Text

Title: MD90 CREW ENCOUNTERED WAKE TURB IN TRAIL OF A B747 AT SFO.

Narrative: B747 WAKE TURB. VECTORED TO ILS FINAL RWY 28L BEHIND A B747. ON GS ON A 12 MI FINAL (ALT 3800 FT MSL) FOR RWY 28L, ACFT ENTERED A 15 DEG ROLL L AND IMMEDIATELY CORRECTED TO THE R WITH PLT INPUT. 2 MORE OSCILLATIONS OCCURRED ASSOCIATED WITH A NOTICEABLE SINK RATE. THE PERIOD OF THIS EVENT LASTED 3-4 SECONDS. AFTER PWR WAS ADDED ACFT EXITED WAKE FROM B747 5 MI AHEAD. APCH WAS CONTINUED WITH DSCNT ABOVE GS AND WAS UNEVENTFUL THROUGH LNDG.

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.