A wide body freight aircraft flight crew reported severe clear air turbulence with a 40 KT airspeed ...

Attributes
ACN	1432549
Time
Date	201703
Local Time Of Day	1201-1800
Place
Locale Reference	ZDV.ARTCC
State Reference	CO
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Widebody Transport
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Speed All Types Inflight Event / Encounter Weather / Turbulence

Narrative:

During cruise at FL360; approximate location was den 304 radial/120 NM; we experienced severe to extreme turbulence. Airspeed initially increased by 25 kts with simultaneous severe turbulence and an approximate 300 ft increase in altitude and a rapid roll to about 20 degrees of bank. The autopilot disconnected on its own and the airspeed then decayed rapidly by approximately 40 kts to about 20 kts below desired indicated airspeed at which point it may have momentarily entered the lower foot. I immediately pushed the throttles forward to regain airspeed and hand flew the aircraft while the captain called ATC for an immediate descent. We descended to FL340 and regained our desired airspeed in the descent. We exited the severe turbulence about FL350 and once we leveled at FL340 I re-engaged the autopilot. There were no personal injuries. The captain notified maintenance via ACARS and made an [logbook] entry.

Original NASA ASRS Text

Title: A wide body freight aircraft flight crew reported severe clear air turbulence with a 40 KT airspeed fluctuation; a rapid climb and roll. The crew descended from FL380 and into smooth air at FL340.

Narrative: During cruise at FL360; approximate location was DEN 304 radial/120 NM; we experienced Severe to Extreme turbulence. Airspeed initially increased by 25 kts with simultaneous severe turbulence and an approximate 300 FT increase in altitude and a rapid roll to about 20 degrees of bank. The autopilot disconnected on its own and the airspeed then decayed rapidly by approximately 40 kts to about 20 kts below desired indicated airspeed at which point it may have momentarily entered the lower foot. I immediately pushed the throttles forward to regain airspeed and hand flew the aircraft while the Captain called ATC for an immediate descent. We descended to FL340 and regained our desired airspeed in the descent. We exited the severe turbulence about FL350 and once we leveled at FL340 I re-engaged the autopilot. There were no personal injuries. The Captain notified maintenance via ACARS and made an [logbook] entry.

Data retrieved from NASA's ASRS site 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.