Narrative:

On approximately heading of 100 degrees, departure said 'turn right heading 120 degrees and join transition. That heading will put you through the hole.' there were 2 cells ahead and the hole between them was too narrow and getting narrower. Frequent lightning was seen in one of the cells. Both painted on the radar. I asked for a heading of 070 degrees to go north of the l-most cell and am not sure what the reply was. Repeated calls were made requesting clarification. The controller was busy answering several other aircraft who were also deviating. When we could not maintain the assigned heading any more because of the l-most northern cell, I turned left to 060 degrees and started advising mia departure what we were doing. Again, no response until the controller finally gave us a frequency change and we were told to advise them of the 070 degree heading. We were VFR the whole time and did not see any visual or TCASII traffic. The controller did a magnificent job but he and the frequency were simply overloaded. The controller did a professional job in every respect.

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Original NASA ASRS Text

Title: A B737 CAPT TOOK EVASIVE ACTION TO AVOID A SEVERE TSTM NEAR MIA, USING HIS EMER AUTH.

Narrative: ON APPROX HDG OF 100 DEGS, DEP SAID 'TURN R HDG 120 DEGS AND JOIN TRANSITION. THAT HDG WILL PUT YOU THROUGH THE HOLE.' THERE WERE 2 CELLS AHEAD AND THE HOLE BTWN THEM WAS TOO NARROW AND GETTING NARROWER. FREQUENT LIGHTNING WAS SEEN IN ONE OF THE CELLS. BOTH PAINTED ON THE RADAR. I ASKED FOR A HDG OF 070 DEGS TO GO N OF THE L-MOST CELL AND AM NOT SURE WHAT THE REPLY WAS. REPEATED CALLS WERE MADE REQUESTING CLARIFICATION. THE CTLR WAS BUSY ANSWERING SEVERAL OTHER ACFT WHO WERE ALSO DEVIATING. WHEN WE COULD NOT MAINTAIN THE ASSIGNED HDG ANY MORE BECAUSE OF THE L-MOST NORTHERN CELL, I TURNED L TO 060 DEGS AND STARTED ADVISING MIA DEP WHAT WE WERE DOING. AGAIN, NO RESPONSE UNTIL THE CTLR FINALLY GAVE US A FREQ CHANGE AND WE WERE TOLD TO ADVISE THEM OF THE 070 DEG HDG. WE WERE VFR THE WHOLE TIME AND DID NOT SEE ANY VISUAL OR TCASII TFC. THE CTLR DID A MAGNIFICENT JOB BUT HE AND THE FREQ WERE SIMPLY OVERLOADED. THE CTLR DID A PROFESSIONAL JOB IN EVERY RESPECT.

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.