Narrative:

At some point less than an hour after takeoff we were confronted by a huge line of thunderstorms directly ahead and to the east/north east of our position. I am not sure why the captain and dispatcher did not seek an alternate route prior to our departure; perhaps the line of thunderstorms moved in an unanticipated manner. Approaching the line; the only safe way to continue; other than doing a 180 and returning to our departure airport; was to take a southerly deviation which took us more than 50 miles offshore on an aircraft that was not over-water equipped. We had a lot of fuel so that was not an issue at all. I don't approximately know exactly how far offshore we got because I was too busy making sure we did not get too close to these buildups. We were approximately 220 miles or so from msy when we started the deviation. The plan was to skirt the south west side of the thunderstorms and this we did in safety and in smooth air. We reached msy as planned; in fact we were able to stay east of msy; and thereafter continued north to our previously filed route in an uneventful manner. The deviation added about 30 minutes to our scheduled flight plan time; with which the extra fuel was not an issue whatsoever. In lieu of the unexpected size; height; and extent of the line of thunderstorms; I believe this was by far the safest course of action in spite of the assumptive violation of the 50 mile rule.

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Original NASA ASRS Text

Title: An A320 flight crew facing unplanned thunderstorms; flew beyond 50NM offshore while circumnavigating the weather.

Narrative: At some point less than an hour after takeoff we were confronted by a huge line of thunderstorms directly ahead and to the east/north east of our position. I am not sure why the Captain and Dispatcher did not seek an alternate route prior to our departure; perhaps the line of thunderstorms moved in an unanticipated manner. Approaching the line; the only safe way to continue; other than doing a 180 and returning to our departure airport; was to take a southerly deviation which took us more than 50 miles offshore on an aircraft that was not over-water equipped. We had a lot of fuel so that was not an issue at all. I don't approximately know exactly how far offshore we got because I was too busy making sure we did not get too close to these buildups. We were approximately 220 miles or so from MSY when we started the deviation. The plan was to skirt the south west side of the thunderstorms and this we did in safety and in smooth air. We reached MSY as planned; in fact we were able to stay east of MSY; and thereafter continued north to our previously filed route in an uneventful manner. The deviation added about 30 minutes to our scheduled flight plan time; with which the extra fuel was not an issue whatsoever. In lieu of the unexpected size; height; and extent of the line of thunderstorms; I believe this was by far the safest course of action in spite of the assumptive violation of the 50 mile rule.

Data retrieved from NASA's ASRS site 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.