A GRUMMAN 'TIGER' AA-5B HAD TO DECLARE AN EMER DUE TO PENETRATION OF A TSTM.

Narrative

THE ACFT BEING FLOWN WAS AN AA5B/R (GRUMMAN 'TIGER'). THE RTE OF FLT WAS FROM MEM TO HTS ON AN IFR FLT PLAN. ON FILING THE FLT PLAN; THE CURRENT WX FOR MY DEST AND ENRTE WAS CHKED. IN ADDITION; A RADAR PLOT OF THE ENRTE WX WAS PRINTED. PERIODIC INFLT WX CHKS FOR THE DEST WERE MADE WITH THE LCL FSS; FLT WATCH; AND ENRTE ATC. NO CTR WX ADVISORIES WERE GIVEN AND THE DEST WX; CURRENT AND FORECASTED; DID NOT INDICATE THE INFLT WX ENCOUNTERED. APPROX A HALF AN HR PRIOR TO ENTERING THE EMBEDDED LEVEL 5 TSTM; THE ENRTE ATC RADAR HAD GONE OUT. IT WAS SHORTLY AFTER THE CTLR ADVISED US OF THE RADAR OUTAGE AND CONTACT WAS LOST; THAT THE INFLT WX HAZARD WAS ENCOUNTERED. WITH HVY RAIN; VERT GUSTS; AND LOSS OF ACFT DIRECTIONAL AND NAV CTL RAPIDLY DETERIORATING; I REQUESTED A HDG OUT OF THE WX. I IMMEDIATELY ADVISED THE CTR CTLR OF MY INFLT CONDITIONS AND HE ADVISED THAT HIS RADAR WAS STILL DOWN. HE ASKED IF I WANTED TO DECLARE AN EMER AND I REPLIED YES. WITHIN A FEW MOMENTS I REGAINED ACFT CTL AND FLEW INTO VMC CONDITIONS. I WAS THEN IMMEDIATELY HANDED OFF TO HTS APCH CTLR. THE ACFT AND THE OCCUPANTS WERE NOT DAMAGED OR INJURED. RADAR VECTORS TO HTS AND A VISUAL APCH WAS MADE TO A SAFE LNDG. CTR ATC WAS VERY HELPFUL. THE CAUSE OF THE ABOVE OCCURRENCE WAS A RESULT OF SEVERAL MECHANICAL; HUMAN; AND NATURE PERFORMANCE FACTORS; ALL OF WHICH CAME TOGETHER TO CAUSE THE INADVERTENT PENETRATION (IMC) OF A LEVEL 5 EMBEDDED TSTM.