B737 Next Generation Undifferentiated
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 200; Flight Crew Type 16000
Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Regained Aircraft Control
Environment - Non Weather Related; Procedure
We were seven miles behind a 747 on approach to Runway 9 in Miami; flaps 5; 170 knots on glidepath; when the aircraft abruptly went into 30 degrees left bank. We commanded full right aileron and there was no response for an unknown amount of time (possibly three seconds). We regained wings level flight only to encounter another abrupt 30 degree roll to the left with lack of aircraft control. After much discussion; my First Officer and I were worried that after such a 'minor incident' (seven miles behind a 747) that the event should cause such a severe loss of aircraft control. We both agree that the incident should be investigated.
We were 15 miles out on the localizer to Runway 9 at 5000 feet. We were seven miles in trail of a B747. We encountered wake turbulence and the aircraft yawed to the left 30+ degrees for 3-5 seconds. We inputted right aileron with no results. The aircraft returned to level flight on its own and immediately went into a 30+ degree left bank turn for 3-5 seconds.
B737 NG flight crew reported momentary loss of control during a wake turbulence encounter on approach to MIA in trail of a B747.