Flight crew of B757-200 exercise emergency authority/authorized to avoid WX en route to ZZZ, first o...

Attributes
ACN	630362
Time
Date	200409
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzzz.airport
State Reference	FO
Altitude	msl single value : 35000
Environment
Weather Elements	Thunderstorm
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Route In Use	enroute : atlantic
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	630362
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	inflight encounter : weather other anomaly other other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency flight crew : exited adverse environment flight crew : took evasive action flight crew : returned to intended or assigned course
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance Weather
Primary Problem	Weather

Narrative:

During flight on oceanic airway flight encountered a twring thunderstorm that exceeded the aircraft's altitude and showed a high degree of reflectivity and intensity on the radar. Well before reaching the cell, I called ZZZ radio and informed them of our need to deviate west of track to avoid the build-up. ZZZ radio told us to standby. We finally reached a point where we needed to exercise our good judgement and emergency authority/authorized and maneuver the aircraft to avoid penetrating the cell. Captain declared his emergency authority/authorized over the HF radio to ZZZ and we deviated to the west off course to avoid the storm. ZZZ radio acknowledged captain's call declaring his emergency authority/authorized and had no further comment on the incident to us at that time.

Original NASA ASRS Text

Title: FLT CREW OF B757-200 EXERCISE EMER AUTH TO AVOID WX ENRTE TO ZZZ, FO.

Narrative: DURING FLT ON OCEANIC AIRWAY FLT ENCOUNTERED A TWRING TSTM THAT EXCEEDED THE ACFT'S ALT AND SHOWED A HIGH DEG OF REFLECTIVITY AND INTENSITY ON THE RADAR. WELL BEFORE REACHING THE CELL, I CALLED ZZZ RADIO AND INFORMED THEM OF OUR NEED TO DEVIATE W OF TRACK TO AVOID THE BUILD-UP. ZZZ RADIO TOLD US TO STANDBY. WE FINALLY REACHED A POINT WHERE WE NEEDED TO EXERCISE OUR GOOD JUDGEMENT AND EMER AUTH AND MANEUVER THE ACFT TO AVOID PENETRATING THE CELL. CAPT DECLARED HIS EMER AUTH OVER THE HF RADIO TO ZZZ AND WE DEVIATED TO THE W OFF COURSE TO AVOID THE STORM. ZZZ RADIO ACKNOWLEDGED CAPT'S CALL DECLARING HIS EMER AUTH AND HAD NO FURTHER COMMENT ON THE INCIDENT TO US AT THAT TIME.

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.

Flight crew of B757-200 exercise emergency authority/authorized to avoid WX en route to ZZZ, first officer.