B777-200 flight crew has WX radar fail; declares emergency and diverts for landing.

Attributes
ACN	718887
Time
Date	200612
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zzz.artcc
State Reference	US
Altitude	msl single value : 37000
Environment
Flight Conditions	VMC VMC
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	B777-200
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 : 159 flight time total : 16800 flight time type : 159
ASRS Report	718887
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 150 flight time total : 15000 flight time type : 1800
ASRS Report	718888
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather
Independent Detector	aircraft equipment other aircraft equipment : radar indication other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : diverted to another airport flight crew : declared emergency
Supplementary
Problem Areas	Aircraft Weather
Primary Problem	Aircraft

Narrative:

Approaching pet; both radars failed. Radio discussion with maintenance and dispatch; with attempt at resetting radar via circuit breaker cycling to no avail. After analyzing WX in ZZZ1 as well as other destinations; captain and dispatch agreed on return to ZZZ. Attempted reroute with ATC via cpdlc and HF. Dispatch advised he was attempting coordination and to expect left turn to zzzzz. When unable ATC contact broadcast intentions on X frequency and declared emergency. As we turned off track center contacted us via ZZZ radio. We advised now off track. ATC then cleared us to cross the track at FL350 direct ZZZZZ1; rxxx; ZZZZ2; ZZZZ3. Flight proceeded to ZZZ with normal landing in VMC. Fuel on board approximately 25000 pounds at landing.

Original NASA ASRS Text

Title: B777-200 FLT CREW HAS WX RADAR FAIL; DECLARES EMER AND DIVERTS FOR LNDG.

Narrative: APCHING PET; BOTH RADARS FAILED. RADIO DISCUSSION WITH MAINT AND DISPATCH; WITH ATTEMPT AT RESETTING RADAR VIA CIRCUIT BREAKER CYCLING TO NO AVAIL. AFTER ANALYZING WX IN ZZZ1 AS WELL AS OTHER DESTS; CAPT AND DISPATCH AGREED ON RETURN TO ZZZ. ATTEMPTED REROUTE WITH ATC VIA CPDLC AND HF. DISPATCH ADVISED HE WAS ATTEMPTING COORD AND TO EXPECT L TURN TO ZZZZZ. WHEN UNABLE ATC CONTACT BROADCAST INTENTIONS ON X FREQ AND DECLARED EMER. AS WE TURNED OFF TRACK CTR CONTACTED US VIA ZZZ RADIO. WE ADVISED NOW OFF TRACK. ATC THEN CLRED US TO CROSS THE TRACK AT FL350 DIRECT ZZZZZ1; RXXX; ZZZZ2; ZZZZ3. FLT PROCEEDED TO ZZZ WITH NORMAL LNDG IN VMC. FUEL ON BOARD APPROX 25000 LBS AT LNDG.

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.