A B737 captain reported encountering wake turbulence 12 miles in trail of a B747 on approach to MMMX...

Attributes
ACN	1292603
Time
Date	201509
Local Time Of Day	1801-2400
Place
Locale Reference	MMMX.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR AVSAR3B
Flight Plan	IFR
Aircraft 2
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Experience	Flight Crew Last 90 Days 168 Flight Crew Total 17000 Flight Crew Type 7491
Events
Anomaly	Inflight Event / Encounter Wake Vortex Encounter

Narrative:

Descending on the avsar 3B arrival to [runway] 23L at MMMX we encountered wake turbulence from a B-747 12 miles ahead on the same arrival. We adjusted our speed and descent rate to avoid any further encounter. A few minutes later we were cleared for the ILS 23L and to caution wake turbulence behind the 747. The following controller told us to turn to a 160 heading to intercept the ILS. I told him I didn't want to cut the turn to the ILS to reduce our wake turbulence separation. He insisted that we turn at that time. We began the turn as requested but at a gradual rate to maintain a safe distance. The wind was out of the east at about 7 kts which would have maintained the wake on the glide slope. We landed uneventfully.

Original NASA ASRS Text

Title: A B737 Captain reported encountering wake turbulence 12 miles in trail of a B747 on approach to MMMX.

Narrative: Descending on the AVSAR 3B arrival to [Runway] 23L at MMMX we encountered wake turbulence from a B-747 12 miles ahead on the same arrival. We adjusted our speed and descent rate to avoid any further encounter. A few minutes later we were cleared for the ILS 23L and to caution wake turbulence behind the 747. The following controller told us to turn to a 160 heading to intercept the ILS. I told him I didn't want to cut the turn to the ILS to reduce our wake turbulence separation. He insisted that we turn at that time. We began the turn as requested but at a gradual rate to maintain a safe distance. The wind was out of the east at about 7 kts which would have maintained the wake on the glide slope. We landed uneventfully.

Data retrieved from NASA's ASRS site 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.