|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Locale Reference||airport : zzz.airport|
|Altitude||msl single value : 28500|
|Controlling Facilities||artcc : zzz.artcc|
|Operator||common carrier : air carrier|
|Make Model Name||B737-500|
|Operating Under FAR Part||Part 121|
|Flight Phase||descent : intermediate altitude|
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Experience||flight time last 90 days : 180|
flight time total : 16000
flight time type : 4000
|Anomaly||inflight encounter : wake turbulence|
|Independent Detector||other flight crewa|
|Resolutory Action||controller : separated traffic|
flight crew : exited adverse environment
flight crew : regained aircraft control
|Problem Areas||Environmental Factor|
|Primary Problem||Environmental Factor|
Mod turbulence was occurring at cruise at 37000 ft through 32000 ft during the descent. Below 30000 ft it smoothed out as we were below the clouds. I turned the seat belt sign off. At approximately 28500 ft; we hit a severe bump and the aircraft autoplt and autothrottle kicked off with the aircraft's wing dropping 35-45 degree turn to the right. We were in a descent so I'm not sure what the loss of altitude was. I regained control and notified ATC of the severe turbulence to warn other descending behind us. I called the back to make sure everyone was ok; which everyone was. The first officer then sent a message to maintenance. I asked ATC if we were following anyone. ATC said only a B747; but he is 20 miles ahead and 4000 ft below you. At about that time we started hitting his wake turbulence again. I requested an off set for the descent. The rest of the flight was normal.
Original NASA ASRS Text
Title: B737-500 ENCOUNTERS LIKELY WAKE TURBULENCE IN DSCNT FOLLOWING B747.
Narrative: MOD TURBULENCE WAS OCCURRING AT CRUISE AT 37000 FT THROUGH 32000 FT DURING THE DSCNT. BELOW 30000 FT IT SMOOTHED OUT AS WE WERE BELOW THE CLOUDS. I TURNED THE SEAT BELT SIGN OFF. AT APPROX 28500 FT; WE HIT A SEVERE BUMP AND THE ACFT AUTOPLT AND AUTOTHROTTLE KICKED OFF WITH THE ACFT'S WING DROPPING 35-45 DEGREE TURN TO THE R. WE WERE IN A DSCNT SO I'M NOT SURE WHAT THE LOSS OF ALTITUDE WAS. I REGAINED CTL AND NOTIFIED ATC OF THE SEVERE TURB TO WARN OTHER DSNDING BEHIND US. I CALLED THE BACK TO MAKE SURE EVERYONE WAS OK; WHICH EVERYONE WAS. THE FO THEN SENT A MESSAGE TO MAINT. I ASKED ATC IF WE WERE FOLLOWING ANYONE. ATC SAID ONLY A B747; BUT HE IS 20 MILES AHEAD AND 4000 FT BELOW YOU. AT ABOUT THAT TIME WE STARTED HITTING HIS WAKE TURB AGAIN. I REQUESTED AN OFF SET FOR THE DSCNT. THE REST OF THE FLT WAS NORMAL.
Data retrieved from NASA's ASRS site as of May 2009 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.