Narrative:

I remember thinking at this time that the entire bjc environment that morning seemed to be somewhat accident prone. Later on that preceding flight, on a practice ILS runway 29R approach, I was given a late vector, which took me inevitably through the final approach course just outside of the FAF. Due to that controller error (for which he apologized) I was unable to complete that approach and was given a long series of vectors over downtown denver and over dia for a second attempt. By this time I had a general wariness concerning the sits at both den approach and bjc ground that morning, although as far as I could tell, the operation rates were not particularly high. Now to the subject flight, which departed a few mins after the preceding flight described above. I was in the left front seat, and was PIC and PF. A non pilot avionics support specialist occupied the right front seat. A current pilot and a non pilot FBO employee occupied the rear seats. After departing bjc VFR and flying north to perform some avionics tests, upon our return I requested and was cleared for a practice ILS runway 29R approach to a full stop at bjc. Again, and reminiscent of the prior flight that day, I was vectored through the final approach course (without prior notification) and then brought back around in a series of left turns for an intercept from the south. Once established on the localizer for a coupled approach, I was asked 3 times to slow to minimum safe approach speed. Upon transitioning the OM, whereupon we were cleared to land as #2 for runway 29R, following traffic well ahead of us. At 400 ft above touchdown zone, with landing assured, I extended full flaps and reduced speed to 77 KTS, still well stabilized and still exactly on localizer and GS. At only 350 ft above touchdown zone, without prior warning and without any apparent conflict visible or announced, I was instructed to 'break off' the approach, turn or circle (I can't remember which term was used) north, and enter a left (or possibly right, again, I can't recall) downwind to runway 29R (or maybe runway 11L, as again I can't recall). To comply with the controller's presumably necessary change of plan, I was executing an unplanned turn at very low altitude in a normally aspirated airplane with all seats occupied under performance limitations consistent with an approximately 8000 ft density altitude condition. Not an ideal situation. Furthermore, per visual ahead and per the operating sky watch (TCASII-like active traffic surveillance) 360 degree display, neither of which indicated any relevant traffic, I in retrospect have concluded that this extremely low 'break off' was merely to effect a change in active runways from runway 29R and runway 29L to runway 11L and runway 11R. Anyway, as a result of being distraction by immediately having to go to full power, turn, retract landing gear, accelerate, retract flaps, and climb to a safe altitude, I (after apparently subconsciously reading back her instructions correctly) misremembered the new clearance and, believing that I had been instructed to execute a right 270 degree turn to the south to eventually enter a left downwind to runway 29L, and after confirming that intention with the pilot in the right back seat, proceeded to do so. I am now guessing in retrospect that the local controller in fact said 'break off your approach, turn north, and enter a left downwind for runway 11L.' anyway, upon observing that I had come around to a southerly heading, the controller pointed out my error, for which I apologized, and cleared me for a right downwind to runway 11R. There was no further comment by the local or ground controller, so I assume no loss of separation resulted. I am writing to suggest that controllers be counseled to if at all possible avoid surprising pilots in the way I was surprised yesterday, to remain aware of aircraft limitations during conditions of high density altitude, to announce on frequency any possible active runway changes so that pilots will know whether a subsequent sudden canceled landing clearance has resulted from an emergency separation issue or merely a runway change, and to stay ahead of the situation so as to avoid 'breaking off' approachs at 350 ft above touchdown zone. The unusual situation of having to retract the landing gear to regain pattern altitude then immediately land is a sequence conducive to a gear-up landing. In retrospect, and especially had I known that the turn instruction was not resulting from an unexpected missed approach of and potential loss of minimum separation from the aircraft ahead, I would have replied' unable turn due to airspeed and altitude, would you like for n-number to execute the published missed approach procedure?' I feel that I have learned an important lesson about thoughtlessly accepting hazardous controller instructions. Apparently, coping with the potential stall/spin or CFIT scenario flushed my short-term memory of the complicated and unexpected clearance.

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Original NASA ASRS Text

Title: AN M20R ATP PLT LOSES HIS SITUATIONAL AWARENESS ON THE ILS TO RWY 29R WHEN GIVEN AN UNEXPECTED GAR AT A LOW ALT DURING A RWY CHANGE AT BJC, CO.

Narrative: I REMEMBER THINKING AT THIS TIME THAT THE ENTIRE BJC ENVIRONMENT THAT MORNING SEEMED TO BE SOMEWHAT ACCIDENT PRONE. LATER ON THAT PRECEDING FLT, ON A PRACTICE ILS RWY 29R APCH, I WAS GIVEN A LATE VECTOR, WHICH TOOK ME INEVITABLY THROUGH THE FINAL APCH COURSE JUST OUTSIDE OF THE FAF. DUE TO THAT CTLR ERROR (FOR WHICH HE APOLOGIZED) I WAS UNABLE TO COMPLETE THAT APCH AND WAS GIVEN A LONG SERIES OF VECTORS OVER DOWNTOWN DENVER AND OVER DIA FOR A SECOND ATTEMPT. BY THIS TIME I HAD A GENERAL WARINESS CONCERNING THE SITS AT BOTH DEN APCH AND BJC GND THAT MORNING, ALTHOUGH AS FAR AS I COULD TELL, THE OP RATES WERE NOT PARTICULARLY HIGH. NOW TO THE SUBJECT FLT, WHICH DEPARTED A FEW MINS AFTER THE PRECEDING FLT DESCRIBED ABOVE. I WAS IN THE L FRONT SEAT, AND WAS PIC AND PF. A NON PLT AVIONICS SUPPORT SPECIALIST OCCUPIED THE R FRONT SEAT. A CURRENT PLT AND A NON PLT FBO EMPLOYEE OCCUPIED THE REAR SEATS. AFTER DEPARTING BJC VFR AND FLYING N TO PERFORM SOME AVIONICS TESTS, UPON OUR RETURN I REQUESTED AND WAS CLRED FOR A PRACTICE ILS RWY 29R APCH TO A FULL STOP AT BJC. AGAIN, AND REMINISCENT OF THE PRIOR FLT THAT DAY, I WAS VECTORED THROUGH THE FINAL APCH COURSE (WITHOUT PRIOR NOTIFICATION) AND THEN BROUGHT BACK AROUND IN A SERIES OF L TURNS FOR AN INTERCEPT FROM THE S. ONCE ESTABLISHED ON THE LOC FOR A COUPLED APCH, I WAS ASKED 3 TIMES TO SLOW TO MINIMUM SAFE APCH SPD. UPON TRANSITIONING THE OM, WHEREUPON WE WERE CLRED TO LAND AS #2 FOR RWY 29R, FOLLOWING TFC WELL AHEAD OF US. AT 400 FT ABOVE TOUCHDOWN ZONE, WITH LNDG ASSURED, I EXTENDED FULL FLAPS AND REDUCED SPD TO 77 KTS, STILL WELL STABILIZED AND STILL EXACTLY ON LOC AND GS. AT ONLY 350 FT ABOVE TOUCHDOWN ZONE, WITHOUT PRIOR WARNING AND WITHOUT ANY APPARENT CONFLICT VISIBLE OR ANNOUNCED, I WAS INSTRUCTED TO 'BREAK OFF' THE APCH, TURN OR CIRCLE (I CAN'T REMEMBER WHICH TERM WAS USED) N, AND ENTER A L (OR POSSIBLY R, AGAIN, I CAN'T RECALL) DOWNWIND TO RWY 29R (OR MAYBE RWY 11L, AS AGAIN I CAN'T RECALL). TO COMPLY WITH THE CTLR'S PRESUMABLY NECESSARY CHANGE OF PLAN, I WAS EXECUTING AN UNPLANNED TURN AT VERY LOW ALT IN A NORMALLY ASPIRATED AIRPLANE WITH ALL SEATS OCCUPIED UNDER PERFORMANCE LIMITATIONS CONSISTENT WITH AN APPROX 8000 FT DENSITY ALT CONDITION. NOT AN IDEAL SIT. FURTHERMORE, PER VISUAL AHEAD AND PER THE OPERATING SKY WATCH (TCASII-LIKE ACTIVE TFC SURVEILLANCE) 360 DEG DISPLAY, NEITHER OF WHICH INDICATED ANY RELEVANT TFC, I IN RETROSPECT HAVE CONCLUDED THAT THIS EXTREMELY LOW 'BREAK OFF' WAS MERELY TO EFFECT A CHANGE IN ACTIVE RWYS FROM RWY 29R AND RWY 29L TO RWY 11L AND RWY 11R. ANYWAY, AS A RESULT OF BEING DISTR BY IMMEDIATELY HAVING TO GO TO FULL PWR, TURN, RETRACT LNDG GEAR, ACCELERATE, RETRACT FLAPS, AND CLB TO A SAFE ALT, I (AFTER APPARENTLY SUBCONSCIOUSLY READING BACK HER INSTRUCTIONS CORRECTLY) MISREMEMBERED THE NEW CLRNC AND, BELIEVING THAT I HAD BEEN INSTRUCTED TO EXECUTE A R 270 DEG TURN TO THE S TO EVENTUALLY ENTER A L DOWNWIND TO RWY 29L, AND AFTER CONFIRMING THAT INTENTION WITH THE PLT IN THE R BACK SEAT, PROCEEDED TO DO SO. I AM NOW GUESSING IN RETROSPECT THAT THE LCL CTLR IN FACT SAID 'BREAK OFF YOUR APCH, TURN N, AND ENTER A L DOWNWIND FOR RWY 11L.' ANYWAY, UPON OBSERVING THAT I HAD COME AROUND TO A SOUTHERLY HDG, THE CTLR POINTED OUT MY ERROR, FOR WHICH I APOLOGIZED, AND CLRED ME FOR A R DOWNWIND TO RWY 11R. THERE WAS NO FURTHER COMMENT BY THE LCL OR GND CTLR, SO I ASSUME NO LOSS OF SEPARATION RESULTED. I AM WRITING TO SUGGEST THAT CTLRS BE COUNSELED TO IF AT ALL POSSIBLE AVOID SURPRISING PLTS IN THE WAY I WAS SURPRISED YESTERDAY, TO REMAIN AWARE OF ACFT LIMITATIONS DURING CONDITIONS OF HIGH DENSITY ALT, TO ANNOUNCE ON FREQ ANY POSSIBLE ACTIVE RWY CHANGES SO THAT PLTS WILL KNOW WHETHER A SUBSEQUENT SUDDEN CANCELED LNDG CLRNC HAS RESULTED FROM AN EMER SEPARATION ISSUE OR MERELY A RWY CHANGE, AND TO STAY AHEAD OF THE SIT SO AS TO AVOID 'BREAKING OFF' APCHS AT 350 FT ABOVE TOUCHDOWN ZONE. THE UNUSUAL SIT OF HAVING TO RETRACT THE LNDG GEAR TO REGAIN PATTERN ALT THEN IMMEDIATELY LAND IS A SEQUENCE CONDUCIVE TO A GEAR-UP LNDG. IN RETROSPECT, AND ESPECIALLY HAD I KNOWN THAT THE TURN INSTRUCTION WAS NOT RESULTING FROM AN UNEXPECTED MISSED APCH OF AND POTENTIAL LOSS OF MINIMUM SEPARATION FROM THE ACFT AHEAD, I WOULD HAVE REPLIED' UNABLE TURN DUE TO AIRSPD AND ALT, WOULD YOU LIKE FOR N-NUMBER TO EXECUTE THE PUBLISHED MISSED APCH PROC?' I FEEL THAT I HAVE LEARNED AN IMPORTANT LESSON ABOUT THOUGHTLESSLY ACCEPTING HAZARDOUS CTLR INSTRUCTIONS. APPARENTLY, COPING WITH THE POTENTIAL STALL/SPIN OR CFIT SCENARIO FLUSHED MY SHORT-TERM MEMORY OF THE COMPLICATED AND UNEXPECTED CLRNC.

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.