Narrative:

Captain said 'I want you to fly the ILS at gnv coupled in accordance with company policy as if you were going to shoot a mins approach and watch what happens.' approximately 15 NM south of wynds the autoplt in our mdt lock ed onto both a false GS and localizer and started left turn to center the needles both localizer and GS. I disengaged the system returned to original heading and altitude, reengaged autoplt and kns, with 2 more false attempts to fly to non existent airport. Projected impact point 10 NM south of kgnv. Captain then related sad story of trying to convince the company and FAA that false captures approaching kgnv from the south can occur. He had multiple examples of this happening in several different mdts. He claims company's regional chief pilot refuses to believe him on this! FAA flew it once in an small transport and watched one mdt and said it's ok. Having seen it with my own eyes I know it is a dangerous situation. If the crew were complacent, ADF, malfunctioning etc, it could/will lead to an aircraft accident. I'm glad I saw it during day VFR smooth air. At night, in bad WX my first inclination would be to believe centering needles backed up with capture and ignore the ADF, which I have seen 30 degree off, often, in error. I'm a retired naval aviator. I've shot almost 1000 approachs to my carrier, I've been a navy instructor pilot in several aircraft and this false signal is likely to catch any unwarned crew. Captain and first officer are concerned about this matter. It may not happen every time but it does happen with some regularity to mdts and is dangerous, especially to higher performance aircraft that set up for the approach further out. Min fix is to have all jax center controllers aware of the phantom ILS at gnv and not clear aircraft for the approach until they are actually established on the real inbound course. I will call the jax center with this proposal.

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Original NASA ASRS Text

Title: COMMUTER FO COMPLAINT ABOUT FALSE GS AND LOC ON APCH TO GNV.

Narrative: CAPT SAID 'I WANT YOU TO FLY THE ILS AT GNV COUPLED IN ACCORDANCE WITH COMPANY POLICY AS IF YOU WERE GOING TO SHOOT A MINS APCH AND WATCH WHAT HAPPENS.' APPROX 15 NM S OF WYNDS THE AUTOPLT IN OUR MDT LOCK ED ONTO BOTH A FALSE GS AND LOC AND STARTED L TURN TO CENTER THE NEEDLES BOTH LOC AND GS. I DISENGAGED THE SYS RETURNED TO ORIGINAL HDG AND ALT, REENGAGED AUTOPLT AND KNS, WITH 2 MORE FALSE ATTEMPTS TO FLY TO NON EXISTENT ARPT. PROJECTED IMPACT POINT 10 NM S OF KGNV. CAPT THEN RELATED SAD STORY OF TRYING TO CONVINCE THE COMPANY AND FAA THAT FALSE CAPTURES APCHING KGNV FROM THE S CAN OCCUR. HE HAD MULTIPLE EXAMPLES OF THIS HAPPENING IN SEVERAL DIFFERENT MDTS. HE CLAIMS COMPANY'S REGIONAL CHIEF PLT REFUSES TO BELIEVE HIM ON THIS! FAA FLEW IT ONCE IN AN SMT AND WATCHED ONE MDT AND SAID IT'S OK. HAVING SEEN IT WITH MY OWN EYES I KNOW IT IS A DANGEROUS SITUATION. IF THE CREW WERE COMPLACENT, ADF, MALFUNCTIONING ETC, IT COULD/WILL LEAD TO AN ACFT ACCIDENT. I'M GLAD I SAW IT DURING DAY VFR SMOOTH AIR. AT NIGHT, IN BAD WX MY FIRST INCLINATION WOULD BE TO BELIEVE CENTERING NEEDLES BACKED UP WITH CAPTURE AND IGNORE THE ADF, WHICH I HAVE SEEN 30 DEG OFF, OFTEN, IN ERROR. I'M A RETIRED NAVAL AVIATOR. I'VE SHOT ALMOST 1000 APCHS TO MY CARRIER, I'VE BEEN A NAVY INSTRUCTOR PLT IN SEVERAL ACFT AND THIS FALSE SIGNAL IS LIKELY TO CATCH ANY UNWARNED CREW. CAPT AND FO ARE CONCERNED ABOUT THIS MATTER. IT MAY NOT HAPPEN EVERY TIME BUT IT DOES HAPPEN WITH SOME REGULARITY TO MDTS AND IS DANGEROUS, ESPECIALLY TO HIGHER PERFORMANCE ACFT THAT SET UP FOR THE APCH FURTHER OUT. MIN FIX IS TO HAVE ALL JAX CENTER CTLRS AWARE OF THE PHANTOM ILS AT GNV AND NOT CLR ACFT FOR THE APCH UNTIL THEY ARE ACTUALLY ESTABLISHED ON THE REAL INBOUND COURSE. I WILL CALL THE JAX CENTER WITH THIS PROPOSAL.

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.