C150 PLT ENTERS IMC WHILE ON A VFR FLT.

Narrative

CERTIFICATE: PVT PLT. WORKING TOWARDS INST RATING WITH 7.6 HRS CURRENT FLT TRAINING TIME. LCL TIME XX15 DEPARTED FROM SAT TO 8T6 ON A HDG OF 160 DEGS DIRECT TO THE THX VORTAC; THENCE THX 160 DEGS TO 8T6; CRUISE ALT 3500 FT. THE TOTAL DISTANCE IS 87 NM AND USUALLY TAKES ABOUT 45 MINS; A ROUTINE TRIP. THE SAT METAR WAS CALM; BROKEN 250 AND THE ALI METAR (CLOSEST AVAILABLE) WAS CALM; BROKEN 30 AND BOTH WERE TO IMPROVE BY THE TAF. AT APPROX 25 MI INTO THE FLT; I BEGAN TO ENCOUNTER A THIN LAYER AT 3500 FT. BEGAN A DSCNT TO MAINTAIN CLOUD CLRNC; AFTER FORCED DOWN TO 2000 FT MSL. I MADE THE DECISION TO DO A 180 DEG TURN AND RETURN TO SAT. 1/2 WAY THROUGH THE TURN; I ENCOUNTERED SOLID IMC AND BEGAN THE TRANSITION TO FULL PANEL INST FLT. NOT YET TERMINATED BY SAT DEP. AFTER A SHORT BOUT WITH SPATIAL DISORIENTATION; AND IN A R DSNDING BANK; I CORRECTED TO A STRAIGHT AND LEVEL FLT WITH A SLIGHT CLB TO 3000 FT MSL. TUNED TO THE SAT VORTAC AND INTERCEPTED THE 160 DEG RADIAL; WHICH TAKES ME DIRECTLY OVER DOWNTOWN SAN ANTONIO. PROCEEDING INBOUND ON THE 160; WITH APPROX 25 MINS IN SOLID IMC; AT 2200 FT MSL; I RPTED THE ARPT IN SIGHT; AND IT WAS A NORMAL VFR NIGHT LNDG FROM THAT POINT.