Failure of WX radar results in turbulence encounter for A318.

Attributes
ACN	698136
Time
Date	200605
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : den.airport
State Reference	CO
Altitude	msl single value : 39000
Environment
Flight Conditions	IMC
Weather Elements	Turbulence Thunderstorm Rain other
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	A318
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 210 flight time type : 400
ASRS Report	698136
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude inflight encounter : weather inflight encounter : turbulence other anomaly other anomaly
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : regained aircraft control flight crew : exited adverse environment
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft Weather
Primary Problem	Weather

Narrative:

While being vectored around WX using WX radar to avoid cells south of us; our WX radar failed. We encountered severe turbulence approximately 80-100 mi east of den at FL390. We were IMC at the time and encountered an area of severe turbulence which included lightning; hail; st elmo's fire and uncontrollable pitch and roll. As the pilot monitoring; I contacted ARTCC and told them that we had lost our WX radar and requested a heading and block altitude to exit the cell as soon as possible. The captain turned the autoplt off; and because the automatic thrust was not maintaining adequate airspeed; the captain turned the automatic thrust off. The jumpseater turned on the ignition (I had not done so yet). We maintained heading but lost 1000-1500 ft of atl. This lasted approximately 4-5 mins after which we were able to regain control; altitude and airspeed. To restore the WX radar; we tried to reset it by switching it off; then on. The result was unsuccessful. The captain asked the jumpseater to reset the circuit breaker which successfully restored the system. The captain spoke to the flight attendant and learned that there were no injuries; but several upset passenger. When in range; we requested that maintenance meet our aircraft at the gate.

Original NASA ASRS Text

Title: FAILURE OF WX RADAR RESULTS IN TURB ENCOUNTER FOR A318.

Narrative: WHILE BEING VECTORED AROUND WX USING WX RADAR TO AVOID CELLS S OF US; OUR WX RADAR FAILED. WE ENCOUNTERED SEVERE TURB APPROX 80-100 MI E OF DEN AT FL390. WE WERE IMC AT THE TIME AND ENCOUNTERED AN AREA OF SEVERE TURB WHICH INCLUDED LIGHTNING; HAIL; ST ELMO'S FIRE AND UNCTLABLE PITCH AND ROLL. AS THE PLT MONITORING; I CONTACTED ARTCC AND TOLD THEM THAT WE HAD LOST OUR WX RADAR AND REQUESTED A HDG AND BLOCK ALT TO EXIT THE CELL ASAP. THE CAPT TURNED THE AUTOPLT OFF; AND BECAUSE THE AUTO THRUST WAS NOT MAINTAINING ADEQUATE AIRSPD; THE CAPT TURNED THE AUTO THRUST OFF. THE JUMPSEATER TURNED ON THE IGNITION (I HAD NOT DONE SO YET). WE MAINTAINED HDG BUT LOST 1000-1500 FT OF ATL. THIS LASTED APPROX 4-5 MINS AFTER WHICH WE WERE ABLE TO REGAIN CTL; ALT AND AIRSPD. TO RESTORE THE WX RADAR; WE TRIED TO RESET IT BY SWITCHING IT OFF; THEN ON. THE RESULT WAS UNSUCCESSFUL. THE CAPT ASKED THE JUMPSEATER TO RESET THE CIRCUIT BREAKER WHICH SUCCESSFULLY RESTORED THE SYS. THE CAPT SPOKE TO THE FLT ATTENDANT AND LEARNED THAT THERE WERE NO INJURIES; BUT SEVERAL UPSET PAX. WHEN IN RANGE; WE REQUESTED THAT MAINT MEET OUR ACFT AT THE GATE.

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.