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Wake turbulence event occurred during descent into ord between a B737 following a B747 7 mi in trail, both at 250 KTS.
| Attributes | |
| ACN | 563381 |
| Time | |
| Date | 200210 |
| Day | Thu |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | intersection : bearz |
| State Reference | IL |
| Altitude | msl bound lower : 11000 msl bound upper : 12000 |
| Aircraft 1 | |
| Controlling Facilities | tracon : c90.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | descent : approach |
| Route In Use | arrival star : okk 1 |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | tracon : c90.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | B747 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : approach |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time total : 7500 flight time type : 1383 |
| ASRS Report | 563381 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | cabin event other inflight encounter : wake turbulence other anomaly |
| Independent Detector | other controllera other flight crewa other flight crewb |
| Resolutory Action | controller : issued advisory flight crew : overrode automation flight crew : regained aircraft control flight crew : exited adverse environment none taken : insufficient time other |
| Consequence | other |
| Supplementary | |
| Problem Areas | ATC Human Performance Aircraft Flight Crew Human Performance Environmental Factor |
| Primary Problem | Ambiguous |
Narrative:
Inbound to ord on okk 1 arrival, ord approach advised us that we were in trail of a B747. Approaching the bearz intersection on a descent clearance to 11000 ft, we encountered wake turbulence while passing through 12000 ft. Both aircraft were assigned airspeed of 250 KTS from ATC. B747 was approximately 7 NM ahead descending through 11800 ft. First officer was PF with autoplt 'B' engaged. First we observed the yoke correcting with nearly full right aileron, followed by aircraft beginning a smooth but rapid roll to the left. First officer disengaged autoplt and began upset recovery technique with coordinated right aileron and rudder. Maximum roll to left was observed between 35-40 degrees. All passenger were in their seats at time as seatbelt sign was on. The 3 working flight attendants were standing during event. Purser was able to stay upright and mentioned some bruising. Both flight attendants in aft cabin 'floated momentarily' and were unable to remain upright. They also felt they received bruising only. Upon advising ATC of event, we were given altitudes above the B747 for remainder of approach and landing. All 3 flight attendants were able to continue on with the rest of their schedule with no observed injuries.
Original NASA ASRS Text
Title: WAKE TURB EVENT OCCURRED DURING DSCNT INTO ORD BTWN A B737 FOLLOWING A B747 7 MI IN TRAIL, BOTH AT 250 KTS.
Narrative: INBOUND TO ORD ON OKK 1 ARR, ORD APCH ADVISED US THAT WE WERE IN TRAIL OF A B747. APCHING THE BEARZ INTXN ON A DSCNT CLRNC TO 11000 FT, WE ENCOUNTERED WAKE TURB WHILE PASSING THROUGH 12000 FT. BOTH ACFT WERE ASSIGNED AIRSPD OF 250 KTS FROM ATC. B747 WAS APPROX 7 NM AHEAD DSNDING THROUGH 11800 FT. FO WAS PF WITH AUTOPLT 'B' ENGAGED. FIRST WE OBSERVED THE YOKE CORRECTING WITH NEARLY FULL R AILERON, FOLLOWED BY ACFT BEGINNING A SMOOTH BUT RAPID ROLL TO THE L. FO DISENGAGED AUTOPLT AND BEGAN UPSET RECOVERY TECHNIQUE WITH COORDINATED R AILERON AND RUDDER. MAX ROLL TO L WAS OBSERVED BTWN 35-40 DEGS. ALL PAX WERE IN THEIR SEATS AT TIME AS SEATBELT SIGN WAS ON. THE 3 WORKING FLT ATTENDANTS WERE STANDING DURING EVENT. PURSER WAS ABLE TO STAY UPRIGHT AND MENTIONED SOME BRUISING. BOTH FLT ATTENDANTS IN AFT CABIN 'FLOATED MOMENTARILY' AND WERE UNABLE TO REMAIN UPRIGHT. THEY ALSO FELT THEY RECEIVED BRUISING ONLY. UPON ADVISING ATC OF EVENT, WE WERE GIVEN ALTS ABOVE THE B747 FOR REMAINDER OF APCH AND LNDG. ALL 3 FLT ATTENDANTS WERE ABLE TO CONTINUE ON WITH THE REST OF THEIR SCHEDULE WITH NO OBSERVED INJURIES.
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.