C172 PLT ON IFR TRAINING FLT TO VKX DSNDS BELOW ASSIGNED ALT.

Narrative

I WAS OFF MY ASSIGNED ALT BY 700 FT. I WAS ON AN INST TRAINING FLT. IM A 280 HR VFR PLT AND WAS RETURNING FROM CHARLOTTESVILLE; VA (CHO) TO MY HOME ARPT; POTOMAC AIRFIELD (VKX). THE FLT FROM VKX TO CHO WAS UNEVENTFUL; THOUGH A LITTLE STRESSFUL. THE RPTS OF MODERATE TURB BELOW 12000 FT WERE CORRECT (WE WERE AT 4000 FT). THE WINDS AT CHARLOTTESVILLE WERE STRONG AND GUSTY; BUT WE LANDED SAFELY. AFTER LNDG AT CHO; WE TAXIED OFF THE RWY AND IMMEDIATELY FILED A RETURN FLT. (THE CFI DID THE FILING.) OUR ROUTING WASNT AS DIRECT AS WE HAD HOPED; GIVEN THE DETERIORATING WX: CHO-GVE-OJAAY-V376-IRONS-VKX. ABOUT 20 MINS AFTER TKOF FROM CHO; WE WERE IN IMC; WHICH IS SOMETHING I WAS HOPING FOR; BECAUSE ITS GOOD PRACTICE. WHAT I WASNT HOPING FOR WAS THE RIME ICE THAT STARTED TO ACCUMULATE ON OUR CESSNAS WHEELS. WE WERE AT 6000 FT AND ALTHOUGH IT WAS 2 DEGS C; I DIDNT LIKE THE ICE AND WITH MY CFIS CONCURRENCE; I ASKED FOR A LOWER ALT. POTOMAC APCH IMMEDIATELY GAVE US 5000 FT AND SAID THAT IF 5000 FT DIDNT GET US OUT OF ICING CONDITIONS; WE COULD REQUEST AN EVEN LOWER ALT. MEANWHILE; OTHER PLTS WERE REGULARLY ASKING ATC ABOUT THE WX: WHAT DID THEIR WX RADAR PAINT? WITH THE EXCEPTION OF 1 TSTM NEAR WINCHESTER (TO OUR W); THE CTLRS RPTED THAT THEY ONLY SAW LEVEL 1 PRECIP. STILL; THE FACT THAT A NUMBER OF PLTS WERE ASKING TOLD ME THAT THEY WERE NERVOUS. I WAS; TOO. THE FORECAST SAID THAT THERE WAS A CHANCE OF ISOLATED TSTMS. THE TEMP BTWN THE 2 SIDES OF THE COLD FRONT THAT WERE APCHING WASHINGTON; DC; WAS SUFFICIENT TO PRODUCE TSTMS. OUR C172 DIDNT HAVE A STORMSCOPE; BUT I WISH IT HAD. IN IMC AND JUST BELOW THE CLOUDS; ALL WE HAD TO RELY ON WERE WHAT THE CTLRS RADAR SHOWED. THE TURB IN THE CLOUDS WAS MODERATE -- IT WAS HARD TO HOLD THE WINGS LEVEL. THE TURB WAS SLIGHTLY LESS OUT OF THE CLOUDS; BUT IT WAS STILL MODERATE AND WE REDUCED OUR SPD TO MANEUVERING SPD. APPROX 10 MI S OF DCA; WHICH WAS NEXT TO OUR DEST ARPT; ATC ISSUED A MICROBURST ALERT FOR WASHINGTON NATIONAL ARPT. THIS ADDED TO MY ANXIETY LEVEL -- AND; AS I REMOVED MY HOOD; I TOLD THE CFI THAT I WOULD FLY THE APCH TO POTOMAC; BUT THOUGHT THAT HE SHOULD DO THE LNDG. AT AROUND THIS TIME; I STARTED TO DSND FROM OUR ASSIGNED ALT OF 2000 FT. IT WAS ALMOST AN AUTOMATIC RESPONSE: FROM THIS GENERAL LOCATION; ON A VFR FLT; IM USUALLY AT 1300 FT OR DSNDING TO IT; AND THATS JUST WHAT I DID; DESPITE ATCS LAST INSTRUCTION TO US. IM NOT SURE IF I KNEW THAT I WAS STILL SUPPOSED TO BE AT 2000 FT -- THAT IS; IM NOT SURE IF I FORGOT MY ALT ASSIGNMENT; OR IF I JUST WAS ON AUTOPLT; DOING WHAT MY SUBCONSCIOUS THOUGHT I SHOULD DO TO GET DOWN SAFELY. THE CFI AD POINTED OUT MY ALT EXCURSION (USUALLY 100-200 FT; CAUSED IN PART BY THE TURB; AND IN PART BY MY INEXPERIENCE FLYING UNDER THE HOOD) BUT DIDNT MENTION THAT I WAS DSNDING AND HAD DSNDED TO 1300 FT. ALTHOUGH THE CFI AND I DIDNT TALK ABOUT IT; I THINK THAT HE; TOO; WAS BOTH PREOCCUPIED; A LITTLE STRESSED; AND CONCERNED ABOUT THE CONDITIONS IN WHICH WE WERE FLYING AND ABOUT TO LAND. IT WAS WHEN ATC ISSUED A SHARP INSTRUCTION TO US TO CLB TO 1600 FT THAT WE BOTH REALIZED WHAT HAD HAPPENED. I IMMEDIATELY CLBED. ATC WAS EXTREMELY BUSY -- IN ADDITION TO THE SEVERE WX IT WAS RUSH HR AT NATIONAL ARPT. THE CFI LANDED; AND DESPITE THE RAINY; GUSTY CONDITIONS; PUT THE PLANE DOWN SAFELY. HE ELECTED NOT TO FLY THE NORMAL PATTERN; BUT DID A STRAIGHT-IN APCH INSTEAD. IM NOT SURE THAT THERES ANYTHING I COULD HAVE DONE TO PREVENT MY ALTDEV OF 700 FT. I DO KNOW THAT THIS WAS THE MOST STRESSFUL AND SCARY FLT IVE EVER BEEN ON. THE LESSON I DID TAKE HOME IS THAT WHEN I AM UNDER A LOT OF STRESS; THERE IS A MUCH HIGHER CHANCE THAN NORMAL THAT I WILL MAKE A MISTAKE; AND (THIS IS THE IMPORTANT PART) I WONT ALWAYS REALIZE THAT IVE MADE A MISTAKE. THE STRESS; ANXIETY AND FEAR I EXPERIENCED WAS FAR GREATER THAN WHAT I IMAGINED I WOULD FEEL IN THAT KIND OF SIT. IVE READ A LOT OF ARTICLES ABOUT PLTS IN DIFFICULT SITS; AND I ALWAYS IMAGINED THAT I WOULD STAYCOOL; DETACHED AND FULLY AWARE. THERES AN ENORMOUS REALITY GAP BTWN READING ABOUT PLTS WHO ENCOUNTER BAD WX AND ACTUALLY EXPERIENCING IT. WHEN IM UNDER STRESS ITS TIME TO CHK CHKLISTS; INSTS; INSTRUCTIONS; AND CHECK THEM AGAIN. I NEED TO RECOGNIZE AND REMEMBER THAT STRESS; ANXIETY; WORRY AND FEAR; REGARDLESS OF WHETHER THE ACTUAL NATURE OF THE DANGERS; CAN MASK PROBS OF MY OWN MAKING.