Narrative:

On may/xa/97 I was en route from boise, identification, to jackson, wy, in a 1983 C90-1 king air with myself and my wife aboard. I was on an IFR flight plan, having departed boise around XA20 local time. I was in VFR conditions at FL200 above a broken cloud layer. The conditions in jackson were: greater than 6 mi visibility on the ground with calm wind and the cloud bases at 2500 ft. The airport is 6500 ft so the cloud bases were at approximately 8000 ft MSL. The top of the cloud layer was approximately 11000 ft MSL. I was cleared to cross the jackson VORTAC at or above 16000 ft and then cleared for the ILS DME approach into jackson. I was asked to switch to advisory unicom frequency and advise ZLC of my cancellation or down time on the center frequency. The approach plate shows that one should fly the transition from the jackson VORTAC outbound on the localizer to the quirt intersection at 15000 ft and then do a procedure turn while descending to 12000 ft to intercept the localizer at 12000 ft. After crossing the jackson VORTAC at 16000 ft, the next altitude I dialed in was 12000 ft. I continued my descent along the localizer to approximately 13600 ft when center advised an immediate climb to 15000 ft. I responded with an immediate climb to 15000 ft and reported that I was still in VFR conditions (cloud tops were at approximately 11000 ft). At quirt intersection, I reported to center level at 15000 ft for a procedure turn and descended to 12000 ft. I entered the clouds at 11000 ft and flew the ILS to well below the bases at 8500 ft when I canceled IFR with center, contacted unicom and landed uneventfully. This problem was caused by my fixation on the intercept altitude of 12000 ft, instead of more carefully reading the approach chart for the proper transition altitude. Fortunately, I would not have hit any terrain and did not interfere with any other aircraft. This was an important personal lesson in pilot error which has driven home the need for continual training and hyperawareness in all phases of flight.

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Original NASA ASRS Text

Title: THE PLT OF A BE90 DSNDED BELOW 15000 FT TOO SOON DURING AN APCH TRANSITION PROC. THE ARTCC RADAR CTLR SAW THE ERROR AND INSTRUCTED THE PLT TO CLB TO PUBLISHED ALT.

Narrative: ON MAY/XA/97 I WAS ENRTE FROM BOISE, ID, TO JACKSON, WY, IN A 1983 C90-1 KING AIR WITH MYSELF AND MY WIFE ABOARD. I WAS ON AN IFR FLT PLAN, HAVING DEPARTED BOISE AROUND XA20 LCL TIME. I WAS IN VFR CONDITIONS AT FL200 ABOVE A BROKEN CLOUD LAYER. THE CONDITIONS IN JACKSON WERE: GREATER THAN 6 MI VISIBILITY ON THE GND WITH CALM WIND AND THE CLOUD BASES AT 2500 FT. THE ARPT IS 6500 FT SO THE CLOUD BASES WERE AT APPROX 8000 FT MSL. THE TOP OF THE CLOUD LAYER WAS APPROX 11000 FT MSL. I WAS CLRED TO CROSS THE JACKSON VORTAC AT OR ABOVE 16000 FT AND THEN CLRED FOR THE ILS DME APCH INTO JACKSON. I WAS ASKED TO SWITCH TO ADVISORY UNICOM FREQ AND ADVISE ZLC OF MY CANCELLATION OR DOWN TIME ON THE CTR FREQ. THE APCH PLATE SHOWS THAT ONE SHOULD FLY THE TRANSITION FROM THE JACKSON VORTAC OUTBOUND ON THE LOC TO THE QUIRT INTXN AT 15000 FT AND THEN DO A PROC TURN WHILE DSNDING TO 12000 FT TO INTERCEPT THE LOC AT 12000 FT. AFTER XING THE JACKSON VORTAC AT 16000 FT, THE NEXT ALT I DIALED IN WAS 12000 FT. I CONTINUED MY DSCNT ALONG THE LOC TO APPROX 13600 FT WHEN CTR ADVISED AN IMMEDIATE CLB TO 15000 FT. I RESPONDED WITH AN IMMEDIATE CLB TO 15000 FT AND RPTED THAT I WAS STILL IN VFR CONDITIONS (CLOUD TOPS WERE AT APPROX 11000 FT). AT QUIRT INTXN, I RPTED TO CTR LEVEL AT 15000 FT FOR A PROC TURN AND DSNDED TO 12000 FT. I ENTERED THE CLOUDS AT 11000 FT AND FLEW THE ILS TO WELL BELOW THE BASES AT 8500 FT WHEN I CANCELED IFR WITH CTR, CONTACTED UNICOM AND LANDED UNEVENTFULLY. THIS PROB WAS CAUSED BY MY FIXATION ON THE INTERCEPT ALT OF 12000 FT, INSTEAD OF MORE CAREFULLY READING THE APCH CHART FOR THE PROPER TRANSITION ALT. FORTUNATELY, I WOULD NOT HAVE HIT ANY TERRAIN AND DID NOT INTERFERE WITH ANY OTHER ACFT. THIS WAS AN IMPORTANT PERSONAL LESSON IN PLT ERROR WHICH HAS DRIVEN HOME THE NEED FOR CONTINUAL TRAINING AND HYPERAWARENESS IN ALL PHASES OF FLT.

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.