EMS HELI PLT SUFFERS VERTIGO IN MARGINAL WX AND ENTERS TCA.

Narrative

FEELING FATIGUED AFTER BATTLING A PERSISTENT SINUS INFECTION THE PREVIOUS 3 WKS. THAT MORNING AT XA10 HRS I RECEIVED A MEDEVAC FLT REQUEST FROM A NEARBY HOSPITAL. I CHKED AND CONFIRMED THAT CURRENT LCL WX CONDITIONS WERE ABOVE FLT PLANNING MINIMUMS (500 FT) FOR ACCEPTANCE OF THE FLT. I DEPARTED THE HELIPAD AT XA21 HRS AND IMMEDIATELY INITIATED A CALL TO ZZZ TWR FOR A CLRNC INTO THE TCA. MY THIRD CALL WAS ACKNOWLEDGED AND A CLRNC RECEIVED. APPROX 1 MIN LATER; I ENCOUNTERED DETERIORATING WX CONDITIONS (300 SCATTERED; 5 BROKEN; 1 RAIN OR THIN FOG). AFTER NOTIFYING ZZZ TWR; I RECEIVED INSTRUCTIONS TO SQUAWK 1200 ON THE XPONDER. I LOOKED DOWN TO CONFIRM THE CORRECT SQUAWK CODE. WHEN I RETURNED MY FIELD OF VISION TO SCAN OUTSIDE THE ACFT; A SEVERE CASE OF VERTIGO FOLLOWED. IMMEDIATELY I ESTABLISHED AN INST SCAN. A BRIEF PERIOD OF TIME ELAPSED BEFORE I COULD ORIENT MYSELF TO THE ACFT AND DETERMINE MY EXACT POS. BY THAT TIME I HAD PENETRATED 1 MI INTO THE TCA. I IMMEDIATELY EXITED THE TCA AND RETURNED TO BASE. FATIGUE CONTRIBUTED SIGNIFICANTLY TO MY ACTIONS WHICH LED TO A CASE OF SELF INDUCED VERTIGO. BETTER SELF EVALUATION OF BOTH MENTAL AND PHYSICAL CAPABILITIES TO PERFORM FLT DUTIES COULD HAVE PREVENTED THE ABOVE MENTIONED INCIDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR VOLUNTEERED FOR STRUCTURED CALLBACK. STATED THEY WERE CLRED THROUGH ZZZ TCA WHERE HOSPITAL WAS LOCATED. ENTERED ZZZ TCA INADVERTENTLY. WAS USING LORAN FOR THIS FLT.