Medium large transport encounters severe clear air turbulence south of great lakes at FL270.

Attributes
ACN	169531
Time
Date	199102
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : huf
State Reference	IN
Altitude	msl bound lower : 27000 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 185 flight time total : 7000 flight time type : 1100
ASRS Report	169531
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter other other anomaly
Independent Detector	other flight crewa
Resolutory Action	none taken : unable none taken : insufficient time
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation other

Narrative:

Encountered severe turbulence for 20 seconds. Altitude deviation up 500', down 600'.

Original NASA ASRS Text

Title: MLG ENCOUNTERS SEVERE CLEAR AIR TURBULENCE SOUTH OF GREAT LAKES AT FL270.

Narrative: ENCOUNTERED SEVERE TURB FOR 20 SECS. ALT DEV UP 500', DOWN 600'.

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.