Narrative:

On climb out from ZZZ encountered significant WX/thunderstorm activity along departure routing. Significant radio traffic overwhelmed ATC. Approaching several large WX cells; I requested a new vector to remain clear of WX. ATC did not respond. I eventually declared an emergency and turned to avoid the heaviest radar returns. ATC controller responded by telling me to; 'just chill out.' during our evasive turn; we encountered heavy-moderate turbulence; temporary loss of climb capability; and bursts of heavy rain. Once WX avoidance was no longer necessary; I terminated the emergency and accepted a new clearance from ATC. ATC should have been more responsive earlier or developed a better departure routing plan for traffic leaving ZZZ given the WX environment.

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Original NASA ASRS Text

Title: B757 DEP FROM ZZZ AT APPROX FL220; WITH CTR; INITIATED CAPT'S EMER AUTHORITY TO DEVIATE AROUND WX AFTER ATC FAILED TO PROVIDE ASSISTANCE.

Narrative: ON CLBOUT FROM ZZZ ENCOUNTERED SIGNIFICANT WX/TSTM ACTIVITY ALONG DEP ROUTING. SIGNIFICANT RADIO TFC OVERWHELMED ATC. APCHING SEVERAL LARGE WX CELLS; I REQUESTED A NEW VECTOR TO REMAIN CLR OF WX. ATC DID NOT RESPOND. I EVENTUALLY DECLARED AN EMER AND TURNED TO AVOID THE HEAVIEST RADAR RETURNS. ATC CTLR RESPONDED BY TELLING ME TO; 'JUST CHILL OUT.' DURING OUR EVASIVE TURN; WE ENCOUNTERED HVY-MODERATE TURB; TEMPORARY LOSS OF CLB CAPABILITY; AND BURSTS OF HVY RAIN. ONCE WX AVOIDANCE WAS NO LONGER NECESSARY; I TERMINATED THE EMER AND ACCEPTED A NEW CLRNC FROM ATC. ATC SHOULD HAVE BEEN MORE RESPONSIVE EARLIER OR DEVELOPED A BETTER DEP ROUTING PLAN FOR TFC LEAVING ZZZ GIVEN THE WX ENVIRONMENT.

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.