An A320 at FL380 encountered severe clear air turbulence injuring passenger. Emergency declared.

Attributes
ACN	676964
Time
Date	200511
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 38000
Environment
Flight Conditions	VMC
Weather Elements	Turbulence
Light	Night
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp pilot : multi engine
Experience	flight time last 90 days : 120 flight time total : 18000 flight time type : 3000
ASRS Report	676964
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : multi engine pilot : instrument pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 240 flight time total : 19411 flight time type : 2400
ASRS Report	676958
Events
Anomaly	altitude deviation : excursion from assigned altitude cabin event : passenger illness inflight encounter : turbulence other anomaly
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : declared emergency flight crew : exited adverse environment flight crew : regained aircraft control none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Environmental Factor Passenger Human Performance
Primary Problem	Environmental Factor

Narrative:

Routine night IFR flight in smooth air. Sky was clear with stars in sight. Extended overwater segment in VHF. Excellent in-flight visibility with another aircraft on same routing 2000 ft below and 10 mi ahead in sight (tail navigation light) at all times. WX radar was on and in proper tilt; not indicating any WX returns. No observed clouds or lightning prior to or after event. Suddenly encountered unexpected severe turbulence lasting 30 or so seconds. Aircraft lost altitude control; autoplt automatic-disconnected; airspeed went to overspd; unable to read aircraft instruments. All loose objects flew about cockpit. Aircraft climbed to approximately FL390 before able to regain control. Descended back to FL380 and reported event to ATC and company dispatch. No other reports of turbulence in area including aircraft in front by 10 mi and 2000 ft below. Cause of event unknown! Declared medical emergency due to passenger injuries and proceeded to ZZZ; our original destination.

Original NASA ASRS Text

Title: AN A320 AT FL380 ENCOUNTERED SEVERE CLR AIR TURB INJURING PAX. EMER DECLARED.

Narrative: ROUTINE NIGHT IFR FLT IN SMOOTH AIR. SKY WAS CLR WITH STARS IN SIGHT. EXTENDED OVERWATER SEGMENT IN VHF. EXCELLENT INFLT VISIBILITY WITH ANOTHER ACFT ON SAME ROUTING 2000 FT BELOW AND 10 MI AHEAD IN SIGHT (TAIL NAV LIGHT) AT ALL TIMES. WX RADAR WAS ON AND IN PROPER TILT; NOT INDICATING ANY WX RETURNS. NO OBSERVED CLOUDS OR LIGHTNING PRIOR TO OR AFTER EVENT. SUDDENLY ENCOUNTERED UNEXPECTED SEVERE TURB LASTING 30 OR SO SECONDS. ACFT LOST ALT CTL; AUTOPLT AUTO-DISCONNECTED; AIRSPD WENT TO OVERSPD; UNABLE TO READ ACFT INSTS. ALL LOOSE OBJECTS FLEW ABOUT COCKPIT. ACFT CLBED TO APPROX FL390 BEFORE ABLE TO REGAIN CTL. DSNDED BACK TO FL380 AND RPTED EVENT TO ATC AND COMPANY DISPATCH. NO OTHER RPTS OF TURB IN AREA INCLUDING ACFT IN FRONT BY 10 MI AND 2000 FT BELOW. CAUSE OF EVENT UNKNOWN! DECLARED MEDICAL EMER DUE TO PAX INJURIES AND PROCEEDED TO ZZZ; OUR ORIGINAL DEST.

Data retrieved from NASA's ASRS site as of January 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.