CL60 descending simultaneously with a B767 20 mi ahead to FL310 encounters severe wake turbulence.

Attributes
ACN	536904
Time
Date	200201
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	intersection : mazat
State Reference	AZ
Altitude	msl single value : 31000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zab.artcc
Operator	general aviation : corporate
Aircraft 2
Controlling Facilities	artcc : zab.artcc
Operator	common carrier : air carrier
Make Model Name	B767 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : cfi pilot : atp pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 60 flight time total : 11800 flight time type : 4000
ASRS Report	536904
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	inflight encounter : wake turbulence
Independent Detector	other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : exited adverse environment
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance Weather
Primary Problem	Weather

Narrative:

We were approximately 20 mi in trail to a B767 heavy in and out of clouds. Both of us had been cleared for a descent to FL310. Apparently we descended at a higher rate and reached FL310 first. At some point our level flight path crossed their descending flight path and we flew through their wake turbulence. We were rolled approximately 80 degrees to the right and the autoplt disengaged. We regained control and had gained approximately 200 ft in altitude. We did not see the aircraft visually due to clouds and our TCASII did not show it due to its 12 NM range. The controller was surprised we had wake turbulence and agreed to our request for an offset of 5 mi and then a 'direct to' our former fix. We were concerned throughout the arrival because we continued behind the B767 along the same arrival route with the same crossing altitudes and speeds, but we got no further turbulence. All passenger were belted, but flight attendant thrown to floor, no injuries.

Original NASA ASRS Text

Title: CL60 DSNDING SIMULTANEOUSLY WITH A B767 20 MI AHEAD TO FL310 ENCOUNTERS SEVERE WAKE TURB.

Narrative: WE WERE APPROX 20 MI IN TRAIL TO A B767 HVY IN AND OUT OF CLOUDS. BOTH OF US HAD BEEN CLRED FOR A DSCNT TO FL310. APPARENTLY WE DSNDED AT A HIGHER RATE AND REACHED FL310 FIRST. AT SOME POINT OUR LEVEL FLT PATH CROSSED THEIR DSNDING FLT PATH AND WE FLEW THROUGH THEIR WAKE TURB. WE WERE ROLLED APPROX 80 DEGS TO THE R AND THE AUTOPLT DISENGAGED. WE REGAINED CTL AND HAD GAINED APPROX 200 FT IN ALT. WE DID NOT SEE THE ACFT VISUALLY DUE TO CLOUDS AND OUR TCASII DID NOT SHOW IT DUE TO ITS 12 NM RANGE. THE CTLR WAS SURPRISED WE HAD WAKE TURB AND AGREED TO OUR REQUEST FOR AN OFFSET OF 5 MI AND THEN A 'DIRECT TO' OUR FORMER FIX. WE WERE CONCERNED THROUGHOUT THE ARR BECAUSE WE CONTINUED BEHIND THE B767 ALONG THE SAME ARR RTE WITH THE SAME XING ALTS AND SPDS, BUT WE GOT NO FURTHER TURB. ALL PAX WERE BELTED, BUT FLT ATTENDANT THROWN TO FLOOR, NO 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.