Narrative:

We were cruising at FL370 approximately 100 NM northwest of slt VOR in communications with ZOB. We were deviating around numerous level 4 and 5 thunderstorms and had been doing so for approximately the last 700-800 NM. The tops of many of the storms exceeded our own altitude, making overflt impossible. As we prepared to pass between two such closely-spaced build-ups on a southeasterly heading, we observed that the gap we were aiming for began to close rapidly as the 2 cells merged. We assumed a northerly heading (the only course of action) placing a large thunderstorm to our right. Shortly thereafter, ZOB controller requested that we perform a right 360 degree turn to avoid a potential traffic conflict. This would have caused us to penetrate the build-up to our right, which appeared to be very active and had all the indications of severe and/or extreme turbulence. Believing that a right turn would place our aircraft, passenger, and crew in extreme jeopardy, we advised the controller that we were deviating further, (we used captain's emergency authority/authorized under 91.3), left to remain clear of the build-up, which the controller did not approve. The controller requested another aircraft, which apparently was on a converging course, to descend. The aircraft appeared on our TCASII briefly as it did so, and we acquired it visually immediately thereafter. At no time was there a hazard of collision, and an RA (TCASII) was not generated. We then maneuvered clear of the build-up and the flight continued to ewr without further incident. The captain on the ground spoke with the ATC facility supervisor via landline upon arrival in ewr. The supervisor stated that the center separation criteria had been slightly compromised with the above aircraft's never getting closer than 4.1 NM apart. He further stated that he understood our position and that he believed our course of action to be appropriate under the circumstances. This crew firmly believe that the controller nor the flight deck crew did anything wrong. Each party was confronted with a set of problem conflicting with one another. The professionalism of everybody involved contributed to the safe resolution of the situation. The controller does not see what we see. There is not even an accurate radar return WX picture overlaid. This is one of those situation when a rigid (and blind) system does not make room for a very dynamic changing WX problem.

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Original NASA ASRS Text

Title: CONVECTIVE WX REQUIRES ACR CREW TO USE EMER AUTH TO REFUSE ARTCC VECTORS. A TFC SEPARATION PROB RESULTED THAT WAS HANDLED BY ARTCC.

Narrative: WE WERE CRUISING AT FL370 APPROX 100 NM NW OF SLT VOR IN COMS WITH ZOB. WE WERE DEVIATING AROUND NUMEROUS LEVEL 4 AND 5 TSTMS AND HAD BEEN DOING SO FOR APPROX THE LAST 700-800 NM. THE TOPS OF MANY OF THE STORMS EXCEEDED OUR OWN ALT, MAKING OVERFLT IMPOSSIBLE. AS WE PREPARED TO PASS BTWN TWO SUCH CLOSELY-SPACED BUILD-UPS ON A SOUTHEASTERLY HEADING, WE OBSERVED THAT THE GAP WE WERE AIMING FOR BEGAN TO CLOSE RAPIDLY AS THE 2 CELLS MERGED. WE ASSUMED A NORTHERLY HEADING (THE ONLY COURSE OF ACTION) PLACING A LARGE TSTM TO OUR R. SHORTLY THEREAFTER, ZOB CTLR REQUESTED THAT WE PERFORM A R 360 DEG TURN TO AVOID A POTENTIAL TFC CONFLICT. THIS WOULD HAVE CAUSED US TO PENETRATE THE BUILD-UP TO OUR R, WHICH APPEARED TO BE VERY ACTIVE AND HAD ALL THE INDICATIONS OF SEVERE AND/OR EXTREME TURB. BELIEVING THAT A R TURN WOULD PLACE OUR ACFT, PAX, AND CREW IN EXTREME JEOPARDY, WE ADVISED THE CTLR THAT WE WERE DEVIATING FURTHER, (WE USED CAPT'S EMER AUTH UNDER 91.3), L TO REMAIN CLR OF THE BUILD-UP, WHICH THE CTLR DID NOT APPROVE. THE CTLR REQUESTED ANOTHER ACFT, WHICH APPARENTLY WAS ON A CONVERGING COURSE, TO DSND. THE ACFT APPEARED ON OUR TCASII BRIEFLY AS IT DID SO, AND WE ACQUIRED IT VISUALLY IMMEDIATELY THEREAFTER. AT NO TIME WAS THERE A HAZARD OF COLLISION, AND AN RA (TCASII) WAS NOT GENERATED. WE THEN MANEUVERED CLR OF THE BUILD-UP AND THE FLT CONTINUED TO EWR WITHOUT FURTHER INCIDENT. THE CAPT ON THE GND SPOKE WITH THE ATC FACILITY SUPVR VIA LANDLINE UPON ARR IN EWR. THE SUPVR STATED THAT THE CTR SEPARATION CRITERIA HAD BEEN SLIGHTLY COMPROMISED WITH THE ABOVE ACFT'S NEVER GETTING CLOSER THAN 4.1 NM APART. HE FURTHER STATED THAT HE UNDERSTOOD OUR POS AND THAT HE BELIEVED OUR COURSE OF ACTION TO BE APPROPRIATE UNDER THE CIRCUMSTANCES. THIS CREW FIRMLY BELIEVE THAT THE CTLR NOR THE FLT DECK CREW DID ANYTHING WRONG. EACH PARTY WAS CONFRONTED WITH A SET OF PROB CONFLICTING WITH ONE ANOTHER. THE PROFESSIONALISM OF EVERYBODY INVOLVED CONTRIBUTED TO THE SAFE RESOLUTION OF THE SIT. THE CTLR DOES NOT SEE WHAT WE SEE. THERE IS NOT EVEN AN ACCURATE RADAR RETURN WX PICTURE OVERLAID. THIS IS ONE OF THOSE SIT WHEN A RIGID (AND BLIND) SYS DOES NOT MAKE ROOM FOR A VERY DYNAMIC CHANGING WX PROB.

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.