B737 Undifferentiated or Other Model
Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Wake Vortex Encounter; Inflight Event / Encounter Weather / Turbulence
Flight Crew Executed Go Around / Missed Approach
Environment - Non Weather Related; Weather
Approaching 7R at 2;000 FT MSL in moderate turbulence; about 12 mile final the turbulence increased. We found out we were in trail of a B757 and thought we were encountering wake turbulence. Executed go-around. During go-around we experienced large altitude and airspeed deviations. At one time I saw us sinking 1;500 FT per minute and looked at the pilot flying who was trying to climb while airspeed was increasing. I saw airspeed reach approximately 270 KIAS with flaps at 1 or 5. I cannot recall. Flying duties were transferred and we arrested the descent and airspeed control. Changes were happening quickly with altitude clearances and flying the aircraft to keep it in control.I assume we did not have any altitude deviations; but don't really know as we attempted to get above these conditions. We continued our climb above the turbulence and reported severe turbulence to ATC. We diverted to FAI and landed uneventfully. I talked with the flight attendant crew enroute to FAI who informed me that it was a rough ride; but all were well and in their seats and buckled. Several PA's were made; time permitting; enroute and on ground in FAI keeping the passengers informed. I received no complaints from either passengers or flight attendants. On ground in FAI; spoke with Dispatch; Flight Operations; and Maintenance Control. I asked and found out from Dispatch that we were in trail of a B757 and B747. I was having difficulty determining whether it really was severe turbulence or moderate with wake turbulence. I asked and heard that no one else had reported severe turbulence. Based on this information and the fact that I find it difficult that we would be the only flight on a busy final to encounter severe turbulence I told Dispatch; Maintenance Control and the Flight Operations that I thought this was moderate turbulence with wake turbulence and that was how I was going to write it up with flap exceedences.
[Report narrative contained no additional information.]
B737 flight crew reported executing a go-around after encountering moderate turbulence and wake vortex on approach to ANC.