AN LGT FREIGHTER CREW; AT NIGHT; IN TSTMS; STOPPED THEIR DSCNT ON A PLT'S DISCRETION DSCNT TO AVOID A BUILD UP.

Narrative

IN IMC CONDITIONS; WITH CLRNC TO DSND FROM FL290 TO FL240 (AT PLT'S DISCRETION) I STOPPED DSCNT AT FL270. AS I BROKE OUT OF AN OVCST LAYER. I WAS IMMEDIATELY CONFRONTED BY A TSTM (NOT SHOWING ON THE RADAR) AND CLBED TO FL27.5 TO AVOID IT. ZID ASKED ABOUT OUR ALT. I SAID WE HAD CLBED TO AVOID A TSTM. HE SAID SOMETHING ELSE ABOUT THE ALT AND I REPLIED THAT I WAS DECLARING AN EMER TO AVOID THE TSTM. A COUPLE OF MINS LATER HE ASKED IF THE EMER WAS OVER AND I SAID YES. NO OTHER DISCUSSION OCCURRED ABOUT THE ALTDEV. ALSO; I FORGOT TO MENTION WE WERE DEVIATING FOR WX AT THE TIME. AFTER THE FLT I CALLED ZID AND SPOKE WITH THE SHIFT SUPVR ABOUT THIS. HE SAID THAT THE CTLR HAD NOT SAID ANYTHING ABOUT IT TO HIM AND THAT IT APPARENTLY WAS NOT A PROBLEM. I GAVE HIM MY NAME AND HE SAID THAT IF THERE WAS A PROBLEM HE WOULD CALL ME. I HAVE NOT HEARD FROM HIM. SUPPLEMENTAL INFO FROM ACN 217754. JUST BELOW FL270 WE ENCOUNTERED A LAYER OF CLR AIR AND THE CAPT ELECTED TO LEVEL THERE; BUT JUST AHEAD COULD SEE THAT THE CLOUDS WERE BEGINNING TO RISE. AT THAT INSTANT A FLASH OF LIGHTNING WAS OBSERVED IN THE CLOUDS. THE CAPT TURNED OFF THE AUTOPLT AND SIMULTANEOUSLY BEGAN A CLB TO AVOID THE CLOUDS AND CALL TO ATC TO ADVISE THEM OF THE CLB. ATC REPLIED WITH A 'NEGATIVE WE HAVE TFC DSNDING OVER YOU.' THE CAPT THEN REPLIED 'WE'LL HAVE TO DECLARE AN EMER THEN.' AT THIS POINT WE HAD CLBED ABOUT 300 FT AND TURNED SLIGHTLY L OF COURSE; AND FOUND OURSELVES IN THE CLR. WHEN ATC AGAIN INQUIRED ABOUT THE EMER; THE CAPT STATED THAT ALL WAS OK AGAIN.