Narrative:

The event in question occurred during a part 121 scheduled flight which departed anc at approximately XA45. After departing runway 6L on the anc 3 SID, we were instructed by departure control to fly heading 180 degrees until receiving homer VOR, then proceed direct. Upon receiving hom VOR, we proceeded direct, inbound on the approximately 360 degree radial, at a cruise altitude of 11000 ft MSL. En route indications were normal and the flight path crossed several prominent landmarks at the approximately correct position (east/west relative to course). Example: tustmena lake. The localizer DME (back course) approach to runway 21 was briefed and initial descent to 5000 ft MSL was commenced at bout 35 DME, with the appropriate checklist. All navigation indications were normal through this point in the flight. Destination WX was 9-10 mi visibility 12000 scattered 4400 broken to overcast, light winds. At 15-18 DME, we had not received approach clearance and the first officer questioned the controller. His comments were somewhat ambiguous. At that point I instructed the first officer to tell the controller that we were joining the 11 DME arc, and the controller then cleared us for the approach. I then commenced descent to 3800 ft MSL for that segment of the arc. I commented that I would continue to 3600 ft, as we would cross the stepdown radial prior to 3800 ft. At this point the first officer stated that we had already crossed the stepdown and were in fact at/near the lead-in radial. About the same time, I observed that we had crossed the west shoreline of kachemack bay (after breaking out of the overcast layer). At this point we realized there was a problem and I immediately commenced a right turn to a wsw direction and selected the localizer frequency. We had passed through the localizer course and were headed toward high terrain to the east, prior to turning. At this point, we were in visual conditions, with the airport in sight (approximately 8 DME on the localizer frequency) and canceled IFR with homer FSS. We conducted a normal landing and postflt checklists. We then reviewed the event in detail but were unable to determine a cause. Additionally, we verified the operation of the navigation radios prior to the next leg, then confirmed this with ATC radar. A clear statement from the center controller would have been helpful in avoiding this situation.

Google
 

Original NASA ASRS Text

Title: AN MDT CREW ON APCH TO HOMER, AK (PAHO) FLEW THROUGH THE BACK COURSE LOC WHILE FLYING THE ARC TO INTERCEPT.

Narrative: THE EVENT IN QUESTION OCCURRED DURING A PART 121 SCHEDULED FLT WHICH DEPARTED ANC AT APPROX XA45. AFTER DEPARTING RWY 6L ON THE ANC 3 SID, WE WERE INSTRUCTED BY DEP CTL TO FLY HDG 180 DEGS UNTIL RECEIVING HOMER VOR, THEN PROCEED DIRECT. UPON RECEIVING HOM VOR, WE PROCEEDED DIRECT, INBOUND ON THE APPROX 360 DEG RADIAL, AT A CRUISE ALT OF 11000 FT MSL. ENRTE INDICATIONS WERE NORMAL AND THE FLT PATH CROSSED SEVERAL PROMINENT LANDMARKS AT THE APPROX CORRECT POS (E/W RELATIVE TO COURSE). EXAMPLE: TUSTMENA LAKE. THE LOC DME (BACK COURSE) APCH TO RWY 21 WAS BRIEFED AND INITIAL DSCNT TO 5000 FT MSL WAS COMMENCED AT BOUT 35 DME, WITH THE APPROPRIATE CHKLIST. ALL NAV INDICATIONS WERE NORMAL THROUGH THIS POINT IN THE FLT. DEST WX WAS 9-10 MI VISIBILITY 12000 SCATTERED 4400 BROKEN TO OVCST, LIGHT WINDS. AT 15-18 DME, WE HAD NOT RECEIVED APCH CLRNC AND THE FO QUESTIONED THE CTLR. HIS COMMENTS WERE SOMEWHAT AMBIGUOUS. AT THAT POINT I INSTRUCTED THE FO TO TELL THE CTLR THAT WE WERE JOINING THE 11 DME ARC, AND THE CTLR THEN CLRED US FOR THE APCH. I THEN COMMENCED DSCNT TO 3800 FT MSL FOR THAT SEGMENT OF THE ARC. I COMMENTED THAT I WOULD CONTINUE TO 3600 FT, AS WE WOULD CROSS THE STEPDOWN RADIAL PRIOR TO 3800 FT. AT THIS POINT THE FO STATED THAT WE HAD ALREADY CROSSED THE STEPDOWN AND WERE IN FACT AT/NEAR THE LEAD-IN RADIAL. ABOUT THE SAME TIME, I OBSERVED THAT WE HAD CROSSED THE W SHORELINE OF KACHEMACK BAY (AFTER BREAKING OUT OF THE OVCST LAYER). AT THIS POINT WE REALIZED THERE WAS A PROB AND I IMMEDIATELY COMMENCED A R TURN TO A WSW DIRECTION AND SELECTED THE LOC FREQ. WE HAD PASSED THROUGH THE LOC COURSE AND WERE HEADED TOWARD HIGH TERRAIN TO THE E, PRIOR TO TURNING. AT THIS POINT, WE WERE IN VISUAL CONDITIONS, WITH THE ARPT IN SIGHT (APPROX 8 DME ON THE LOC FREQ) AND CANCELED IFR WITH HOMER FSS. WE CONDUCTED A NORMAL LNDG AND POSTFLT CHKLISTS. WE THEN REVIEWED THE EVENT IN DETAIL BUT WERE UNABLE TO DETERMINE A CAUSE. ADDITIONALLY, WE VERIFIED THE OP OF THE NAV RADIOS PRIOR TO THE NEXT LEG, THEN CONFIRMED THIS WITH ATC RADAR. A CLR STATEMENT FROM THE CTR CTLR WOULD HAVE BEEN HELPFUL IN AVOIDING THIS SIT.

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.