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B727 crew inbound to oak runway 29 are alerted by O90 controller to correct from a false localizer signal the same time the flight crew is checking localizer validity.
| Attributes | |
| ACN | 557798 |
| Time | |
| Date | 200208 |
| Day | Thu |
| Local Time Of Day | 0001 To 0600 |
| Place | |
| State Reference | CA |
| Altitude | msl bound lower : 4000 msl bound upper : 5000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tracon : o90.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | B727 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | ils localizer & glide slope : 29 |
| Flight Phase | descent : approach |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : flight engineer pilot : commercial pilot : atp |
| Experience | flight time last 90 days : 58 flight time total : 5000 flight time type : 204 |
| ASRS Report | 557798 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | aircraft equipment problem : critical inflight encounter : weather other anomaly other other spatial deviation |
| Independent Detector | aircraft equipment other aircraft equipment : autoplt/flt director other controllera other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : overrode automation flight crew : returned to intended or assigned course |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Problem Areas | Aircraft Navigational Facility |
| Primary Problem | Navigational Facility |
| Situations | |
| ATC Facility | communication equipment : oak.tower other physical facility |
| Airport | other physical facility |
| Navigational Aid | OAK.ILS |
Narrative:
We were southwest of the eca VOR on the madn 4 arrival to oak. Bay approach assigned us to fly a 220 degree heading until intercepting the runway 29 localizer. The autoplt was engaged and we received a good identify on the localizer. The aircraft turned to a 270 degree heading at the time of localizer capture as indicated on the flight director and autoplt annunciators. Although not visual with oak, we suspected that the autoplt/flight director might have locked on to a false localizer signal. Our company has experienced numerous false localizer captures with runway 29 localizer at oak. While the first officer crosschecked our position with the oak VOR, ATC queried us as to our heading. We responded '270 degrees.' he turned us back to 240 degrees until intercepting the localizer. I disconnected the autoplt and flew an uneventful approach and landing. This continues to be an ongoing problem at oak with the runway 29 localizer. Additionally, our assigned intercept of 220 degrees versus the 294 degree front course might have contributed to the event. Callback conversation with reporter revealed the following information: reporter advised that all company aircraft have reported this problem and is not representative of 1 aircraft type only, though apparently more common in the DC10. Callback conversation with tower specialist revealed the following information: advised that it has been an unresolved problem for over 1 yr. The specialist stated that this problem has been reported by just 1 air carrier. Maintenance has suggested that usage beyond the localizer signal limitation (thought to be 18 mi) may have some influence on aircraft course divergence, but no significant correction to the ILS equipment has been made.
Original NASA ASRS Text
Title: B727 CREW INBOUND TO OAK RWY 29 ARE ALERTED BY O90 CTLR TO CORRECT FROM A FALSE LOC SIGNAL THE SAME TIME THE FLC IS CHKING LOC VALIDITY.
Narrative: WE WERE SW OF THE ECA VOR ON THE MADN 4 ARR TO OAK. BAY APCH ASSIGNED US TO FLY A 220 DEG HDG UNTIL INTERCEPTING THE RWY 29 LOC. THE AUTOPLT WAS ENGAGED AND WE RECEIVED A GOOD IDENT ON THE LOC. THE ACFT TURNED TO A 270 DEG HDG AT THE TIME OF LOC CAPTURE AS INDICATED ON THE FLT DIRECTOR AND AUTOPLT ANNUNCIATORS. ALTHOUGH NOT VISUAL WITH OAK, WE SUSPECTED THAT THE AUTOPLT/FLT DIRECTOR MIGHT HAVE LOCKED ON TO A FALSE LOC SIGNAL. OUR COMPANY HAS EXPERIENCED NUMEROUS FALSE LOC CAPTURES WITH RWY 29 LOC AT OAK. WHILE THE FO XCHKED OUR POS WITH THE OAK VOR, ATC QUERIED US AS TO OUR HDG. WE RESPONDED '270 DEGS.' HE TURNED US BACK TO 240 DEGS UNTIL INTERCEPTING THE LOC. I DISCONNECTED THE AUTOPLT AND FLEW AN UNEVENTFUL APCH AND LNDG. THIS CONTINUES TO BE AN ONGOING PROB AT OAK WITH THE RWY 29 LOC. ADDITIONALLY, OUR ASSIGNED INTERCEPT OF 220 DEGS VERSUS THE 294 DEG FRONT COURSE MIGHT HAVE CONTRIBUTED TO THE EVENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ADVISED THAT ALL COMPANY ACFT HAVE RPTED THIS PROB AND IS NOT REPRESENTATIVE OF 1 ACFT TYPE ONLY, THOUGH APPARENTLY MORE COMMON IN THE DC10. CALLBACK CONVERSATION WITH TWR SPECIALIST REVEALED THE FOLLOWING INFO: ADVISED THAT IT HAS BEEN AN UNRESOLVED PROB FOR OVER 1 YR. THE SPECIALIST STATED THAT THIS PROB HAS BEEN RPTED BY JUST 1 ACR. MAINT HAS SUGGESTED THAT USAGE BEYOND THE LOC SIGNAL LIMITATION (THOUGHT TO BE 18 MI) MAY HAVE SOME INFLUENCE ON ACFT COURSE DIVERGENCE, BUT NO SIGNIFICANT CORRECTION TO THE ILS EQUIP HAS BEEN MADE.
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.