Narrative:

This event occurred early on a sunday morning. We were 1 of only a very few aircraft flying the skies. On approach into sdf from the east; we were cleared direct to the final approach fix for runway 35L which would carry us across the final approach path for runway 35R. On the automatic dependent surveillance broadcast display we noticed an aircraft approaching from the south and soon heard the approach controller clear an air carrier jet for a straight-in approach to runway 35R. The controller then asked us if we had the traffic in sight. After looking at the automatic dependent surveillance broadcast display and outside; we called the aircraft in sight. It was well to our south and it looked like we would be well in front of this aircraft. The controller then told us we should be passing behind this aircraft and to maintain visual separation. He then said we could widen out to the left if as desired. It looked to me that there was no way we could pass behind the aircraft unless we did a 360 degree turn or turned south to meet it head on. Another option would be to maintain altitude; fly west and do a 270 degree turn back to the runway centerline. The controller then asked if we had the airfield in sight and we responded affirmatively. He then cleared us for a visual approach to runway 35L to maintain visual separation from the traffic and cleared us to land. Because we were apparently well out in front of the traffic; the captain elected to descend and configure for landing. As we crossed the extended centerline of runway 35R; the comfortable separation we thought we had on the traffic turned uncomfortable. I do not know how close he was. The last distance I remember observing on the automatic dependent surveillance broadcast display was approximately 3 mi. But; when our paths crossed; it could have been closer -- it was uncomfortable. Lessons I learned: when cleared for a visual approach at night and required to maintain visual separation; I will be extremely wary. This seemingly simple maneuver is fraught with challenges. The major challenge for us this night was; in my view; fatigue. We were legally rested but our previous leg was flown out of our established sleep rest cycle. Rest for this leg was marginal at best. I felt fine starting the leg but about the time we started descent; my body was saying 'you can sleep now.' as a result; I was not up to PAR mentally and did not assertively suggest alternative flight paths to the captain. The second challenge is the difficulty of assessing closure rates and relative position at night; challenging normally but almost impossible when you are tired. The remaining challenge I will definitely consider in the future is the one of not knowing what is going on in the cockpit of the conflicting aircraft. Thinking back; I suspect the other aircraft pilots were tired too and had decided to make best possible speed on their final approach. What looked good at a distance was rendered potentially unsafe because they were coming in faster than I anticipated. The solution for me in the future; given similar circumstances; will be to request a vectored final approach.

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Original NASA ASRS Text

Title: MISCALCULATION OF SPACING BY LCL CTLR RESULTS IN UNCOMFORTABLE XING TFC BY B767 ON R BASE FOR RWY 35L WITH STRAIGHT IN ACFT FOR RWY 35R AT SDF.

Narrative: THIS EVENT OCCURRED EARLY ON A SUNDAY MORNING. WE WERE 1 OF ONLY A VERY FEW ACFT FLYING THE SKIES. ON APCH INTO SDF FROM THE E; WE WERE CLRED DIRECT TO THE FINAL APCH FIX FOR RWY 35L WHICH WOULD CARRY US ACROSS THE FINAL APCH PATH FOR RWY 35R. ON THE AUTO DEPENDENT SURVEILLANCE BROADCAST DISPLAY WE NOTICED AN ACFT APCHING FROM THE S AND SOON HEARD THE APCH CTLR CLR AN ACR JET FOR A STRAIGHT-IN APCH TO RWY 35R. THE CTLR THEN ASKED US IF WE HAD THE TFC IN SIGHT. AFTER LOOKING AT THE AUTO DEPENDENT SURVEILLANCE BROADCAST DISPLAY AND OUTSIDE; WE CALLED THE ACFT IN SIGHT. IT WAS WELL TO OUR S AND IT LOOKED LIKE WE WOULD BE WELL IN FRONT OF THIS ACFT. THE CTLR THEN TOLD US WE SHOULD BE PASSING BEHIND THIS ACFT AND TO MAINTAIN VISUAL SEPARATION. HE THEN SAID WE COULD WIDEN OUT TO THE L IF AS DESIRED. IT LOOKED TO ME THAT THERE WAS NO WAY WE COULD PASS BEHIND THE ACFT UNLESS WE DID A 360 DEG TURN OR TURNED S TO MEET IT HEAD ON. ANOTHER OPTION WOULD BE TO MAINTAIN ALT; FLY W AND DO A 270 DEG TURN BACK TO THE RWY CTRLINE. THE CTLR THEN ASKED IF WE HAD THE AIRFIELD IN SIGHT AND WE RESPONDED AFFIRMATIVELY. HE THEN CLRED US FOR A VISUAL APCH TO RWY 35L TO MAINTAIN VISUAL SEPARATION FROM THE TFC AND CLRED US TO LAND. BECAUSE WE WERE APPARENTLY WELL OUT IN FRONT OF THE TFC; THE CAPT ELECTED TO DSND AND CONFIGURE FOR LNDG. AS WE CROSSED THE EXTENDED CTRLINE OF RWY 35R; THE COMFORTABLE SEPARATION WE THOUGHT WE HAD ON THE TFC TURNED UNCOMFORTABLE. I DO NOT KNOW HOW CLOSE HE WAS. THE LAST DISTANCE I REMEMBER OBSERVING ON THE AUTO DEPENDENT SURVEILLANCE BROADCAST DISPLAY WAS APPROX 3 MI. BUT; WHEN OUR PATHS CROSSED; IT COULD HAVE BEEN CLOSER -- IT WAS UNCOMFORTABLE. LESSONS I LEARNED: WHEN CLRED FOR A VISUAL APCH AT NIGHT AND REQUIRED TO MAINTAIN VISUAL SEPARATION; I WILL BE EXTREMELY WARY. THIS SEEMINGLY SIMPLE MANEUVER IS FRAUGHT WITH CHALLENGES. THE MAJOR CHALLENGE FOR US THIS NIGHT WAS; IN MY VIEW; FATIGUE. WE WERE LEGALLY RESTED BUT OUR PREVIOUS LEG WAS FLOWN OUT OF OUR ESTABLISHED SLEEP REST CYCLE. REST FOR THIS LEG WAS MARGINAL AT BEST. I FELT FINE STARTING THE LEG BUT ABOUT THE TIME WE STARTED DSCNT; MY BODY WAS SAYING 'YOU CAN SLEEP NOW.' AS A RESULT; I WAS NOT UP TO PAR MENTALLY AND DID NOT ASSERTIVELY SUGGEST ALTERNATIVE FLT PATHS TO THE CAPT. THE SECOND CHALLENGE IS THE DIFFICULTY OF ASSESSING CLOSURE RATES AND RELATIVE POS AT NIGHT; CHALLENGING NORMALLY BUT ALMOST IMPOSSIBLE WHEN YOU ARE TIRED. THE REMAINING CHALLENGE I WILL DEFINITELY CONSIDER IN THE FUTURE IS THE ONE OF NOT KNOWING WHAT IS GOING ON IN THE COCKPIT OF THE CONFLICTING ACFT. THINKING BACK; I SUSPECT THE OTHER ACFT PLTS WERE TIRED TOO AND HAD DECIDED TO MAKE BEST POSSIBLE SPD ON THEIR FINAL APCH. WHAT LOOKED GOOD AT A DISTANCE WAS RENDERED POTENTIALLY UNSAFE BECAUSE THEY WERE COMING IN FASTER THAN I ANTICIPATED. THE SOLUTION FOR ME IN THE FUTURE; GIVEN SIMILAR CIRCUMSTANCES; WILL BE TO REQUEST A VECTORED FINAL APCH.

Data retrieved from NASA's ASRS site as of January 2009 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.