Md-11 flight crew reported encountering wake turbulence in trail of a B757 on approach that resulted...

Attributes
ACN	1377576
Time
Date	201608
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	MD-11
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Flight Plan	IFR
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Deviation - Speed All Types Inflight Event / Encounter Wake Vortex Encounter

Narrative:

On final with clearance to fly the ILS; configured flaps 50 and stable with a 16 knot tailwind; we were sequenced behind a B-757 and advised of a 40 kt overtake and a 4 mile separation and asked to slow to our final approach speed which we were presently flying. The preceding aircraft was clearing as we were descending through 300 feet afe; and at 100 feet we flew into the preceding aircraft's wake; resulting in an initial 10 knot loss immediately followed by a 20 knot gain; at which time the captain commanded an immediate go-around; which occurred at approximately 80 feet. The go-around and remainder of the flight was without incident. Lack of adequate spacing behind a 757; given the tailwind conditions on short final; resulting in an approach that became unstable close to the ground. Give ATC feedback on the need to be more proactive with spacing an md-11 and a 757. Ask them to assign an appropriate speed to us earlier under such conditions. We could be more proactive in advising ATC; even after landing; of our observed winds on final when appropriate; especially when spacing and wake separation might be a factor.

Original NASA ASRS Text

Title: MD-11 flight crew reported encountering wake turbulence in trail of a B757 on approach that resulted in speed fluctuations and a go-around.

Narrative: On final with clearance to fly the ILS; configured flaps 50 and stable with a 16 knot tailwind; we were sequenced behind a B-757 and advised of a 40 kt overtake and a 4 mile separation and asked to slow to our final approach speed which we were presently flying. The preceding aircraft was clearing as we were descending through 300 feet AFE; and at 100 feet we flew into the preceding aircraft's wake; resulting in an initial 10 knot loss immediately followed by a 20 knot gain; at which time the Captain commanded an immediate go-around; which occurred at approximately 80 feet. The go-around and remainder of the flight was without incident. Lack of adequate spacing behind a 757; given the tailwind conditions on short final; resulting in an approach that became unstable close to the ground. Give ATC feedback on the need to be more proactive with spacing an MD-11 and a 757. Ask them to assign an appropriate speed to us earlier under such conditions. We could be more proactive in advising ATC; even after landing; of our observed winds on final when appropriate; especially when spacing and wake separation might be a factor.

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.

Md-11 flight crew reported encountering wake turbulence in trail of a B757 on approach that resulted in speed fluctuations and a go-around.