Narrative:

On approach to mdw (visual to runway 31L backed up by ILS to runway 31L) in a ba 3100 jetstream, violent encounter with wake turbulence from preceding boeing 737-200. There was a 5 mi separation between us and the 737. This was confirmed both visually by myself and the captain and mdw radar. We were approximately 2 mi outside the OM and on localizer and GS. We could see the 737 in front of us looked high in respect to the glide path. About this time, we encountered a slight buffet. Seconds later, I had full aileron deflection to the left and was still rolling right at approximately 10-15 degrees per second. Only after abruptly pulling up on the yoke to climb out of the encounter was aircraft control able to be regained. The rest of the approach was flown approximately 2 dots high on the GS and we landed without incident. Factors leading to this are (in my opinion) as follows: the B-737 in question was high on the approach. The wingtip vortices would then be allowed to descend into the glide path where we encounter them. To correct this problem, aircraft -- especially large jet transports -- must stay on the prescribed glide path even in visual conditions!

Related reports:

Google
 

Original NASA ASRS Text

Title: FO OF A JETSTREAM 3100 (LTT) LOST CTL MOMENTARILY WHEN ENCOUNTERING WAKE TURB DURING A VISUAL APCH FOLLOWING A BOEING 737-200 (MLG) 5 MI AHEAD.

Narrative: ON APCH TO MDW (VISUAL TO RWY 31L BACKED UP BY ILS TO RWY 31L) IN A BA 3100 JETSTREAM, VIOLENT ENCOUNTER WITH WAKE TURB FROM PRECEDING BOEING 737-200. THERE WAS A 5 MI SEPARATION BTWN US AND THE 737. THIS WAS CONFIRMED BOTH VISUALLY BY MYSELF AND THE CAPT AND MDW RADAR. WE WERE APPROX 2 MI OUTSIDE THE OM AND ON LOC AND GS. WE COULD SEE THE 737 IN FRONT OF US LOOKED HIGH IN RESPECT TO THE GLIDE PATH. ABOUT THIS TIME, WE ENCOUNTERED A SLIGHT BUFFET. SECONDS LATER, I HAD FULL AILERON DEFLECTION TO THE L AND WAS STILL ROLLING R AT APPROX 10-15 DEGS PER SECOND. ONLY AFTER ABRUPTLY PULLING UP ON THE YOKE TO CLB OUT OF THE ENCOUNTER WAS ACFT CTL ABLE TO BE REGAINED. THE REST OF THE APCH WAS FLOWN APPROX 2 DOTS HIGH ON THE GS AND WE LANDED WITHOUT INCIDENT. FACTORS LEADING TO THIS ARE (IN MY OPINION) AS FOLLOWS: THE B-737 IN QUESTION WAS HIGH ON THE APCH. THE WINGTIP VORTICES WOULD THEN BE ALLOWED TO DSND INTO THE GLIDE PATH WHERE WE ENCOUNTER THEM. TO CORRECT THIS PROB, ACFT -- ESPECIALLY LARGE JET TRANSPORTS -- MUST STAY ON THE PRESCRIBED GLIDE PATH EVEN IN VISUAL CONDITIONS!

Data retrieved from NASA's ASRS site as of July 2007 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.