<< >> NASA ASRS Report 1672283, July 2019

A330 flight crew reported they encountered wake turbulence from a preceding B747 while flying a north atlantic track. Captain descended 300 feet without clearance to avoid the wake.

Attributes
ACN	1672283
Time
Date	201907
Aircraft 1
Make Model Name	A330
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Aircraft 2
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Wake Vortex Encounter

Narrative:

[We were] 23 miles and 2000 feet below and behind [a] B747. We were slop 2 miles right when wind shift put us in moderate turbulence. It was getting worse and required immediate action. [We] descended 300 ft and slid to the other side of his jet wash. Immediately then returned to assigned altitude and told ATC about the minor deviation. Tracks too tight. [I used] captain authority and knowledge.

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Original NASA ASRS Text

Title: A330 flight crew reported they encountered wake turbulence from a preceding B747 while flying a North Atlantic track. Captain descended 300 feet without clearance to avoid the wake.

Narrative: [We were] 23 miles and 2000 feet below and behind [a] B747. We were slop 2 miles right when wind shift put us in moderate turbulence. It was getting worse and required immediate action. [We] descended 300 ft and slid to the other side of his jet wash. Immediately then returned to assigned altitude and told ATC about the minor deviation. Tracks too tight. [I used] Captain authority and knowledge.

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.