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A hawker 1000 on an ILS approach to swf observed several localizer swings and executed a missed approach. The preceding aircraft was idented as a C5.
| Attributes | |
| ACN | 426281 |
| Time | |
| Date | 199901 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : swf |
| State Reference | NY |
| Altitude | agl bound lower : 1000 agl bound upper : 1000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | general aviation : corporate |
| Navigation In Use | Other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | other |
| Navigation In Use | Other |
| Flight Phase | ground other : taxi landing other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 60 flight time total : 9600 flight time type : 3000 |
| ASRS Report | 426281 |
| Person 2 | |
| Affiliation | Other |
| Function | flight crew : captain oversight : pic |
| Events | |
| Anomaly | aircraft equipment problem : less severe other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Supplementary | |
| Air Traffic Incident | other |
Narrative:
We crossed the FAF on an ILS approach as a C5A cargo jet was landing. Localizer was operating normally. At about 1000 ft AGL the localizer needle started to move rapidly from side-to-side as the autoplt was coupled and attempted to lock on the signal. The aircraft started to oscillate. I disengaged the autoplt and attempted to hand fly, but this was futile as the signal was erroneous. I executed a missed approach and requested another attempt. Tower said the localizer was indicating normal. I asked if the C5A was in the ILS critical area. With visibility so low, tower wasn't sure, but thought he might have been. The ramp area for the C5A's is very near the runway. I can only assume the C5A was causing localizer interference while taxiing or doing after landing checks upon clearing the runway, as our second ILS approach was normal with proper signal indications. Many pilots are aware of the ILS critical area upon taxiing to a runway for takeoff, but forget about this area upon landing. We need to emphasize this factor, as we came very close to being an accident.
Original NASA ASRS Text
Title: A HAWKER 1000 ON AN ILS APCH TO SWF OBSERVED SEVERAL LOC SWINGS AND EXECUTED A MISSED APCH. THE PRECEDING ACFT WAS IDENTED AS A C5.
Narrative: WE CROSSED THE FAF ON AN ILS APCH AS A C5A CARGO JET WAS LNDG. LOC WAS OPERATING NORMALLY. AT ABOUT 1000 FT AGL THE LOC NEEDLE STARTED TO MOVE RAPIDLY FROM SIDE-TO-SIDE AS THE AUTOPLT WAS COUPLED AND ATTEMPTED TO LOCK ON THE SIGNAL. THE ACFT STARTED TO OSCILLATE. I DISENGAGED THE AUTOPLT AND ATTEMPTED TO HAND FLY, BUT THIS WAS FUTILE AS THE SIGNAL WAS ERRONEOUS. I EXECUTED A MISSED APCH AND REQUESTED ANOTHER ATTEMPT. TWR SAID THE LOC WAS INDICATING NORMAL. I ASKED IF THE C5A WAS IN THE ILS CRITICAL AREA. WITH VISIBILITY SO LOW, TWR WASN'T SURE, BUT THOUGHT HE MIGHT HAVE BEEN. THE RAMP AREA FOR THE C5A'S IS VERY NEAR THE RWY. I CAN ONLY ASSUME THE C5A WAS CAUSING LOC INTERFERENCE WHILE TAXIING OR DOING AFTER LNDG CHKS UPON CLRING THE RWY, AS OUR SECOND ILS APCH WAS NORMAL WITH PROPER SIGNAL INDICATIONS. MANY PLTS ARE AWARE OF THE ILS CRITICAL AREA UPON TAXIING TO A RWY FOR TKOF, BUT FORGET ABOUT THIS AREA UPON LNDG. WE NEED TO EMPHASIZE THIS FACTOR, AS WE CAME VERY CLOSE TO BEING AN ACCIDENT.
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.