Small aircraft has false localizer signal, descends below final approach fix crossing altitude.

Attributes
ACN	254372
Time
Date	199310
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : cak
State Reference	OH
Altitude	msl bound lower : 2200 msl bound upper : 3200
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cak
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 66 flight time total : 333 flight time type : 270
ASRS Report	254372
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude
Independent Detector	other flight crewa
Resolutory Action	flight crew : became reoriented
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Flight from ytz to cak in IMC over entire route, uneventful until inbound from approximately 18 mi out and on localizer, cak runway 23. Cleared for ILS 23 by approach and descended to 3200 ft (MSL), awaiting crossing OM to descend to MDA. Heard OM audio clearly (front seat, non-pilot passenger heard also, asked what the beeping tone meant) -- confirmed on high sensitivity. No OM light indication. Signal increased then decreased, as if passage over marker. At this time, approach handed me off to tower. Believing I had crossed the OM, began descent to MDA. No GS reception. Crossed true OM thereafter, aural and light indication, altitude 2200 ft MSL, 1000 ft below final approach fix crossing altitude. Reported receiving false OM to tower by phone after landing. Result: normal landing, no mishap. Comment/action: will have ILS/mkb electronics checked in aircraft. Airport will check its ILS equipment -- they have had reports of false OM on ILS 19, but this is the first time on ILS 23. In future, if uncertain of position (light but no aural or vise versa, remain at altitude until sure (check via VOR cross radial or radar) or go missed approach, rather than go below a segment minimum altitude until sure of being inside final approach fix. Callback conversation with reporter revealed the following information: reporter states he had aircraft checked and a loose antenna coupling was discovered. He believes it was his equipment, not akron ILS that was the problem. GS went out at same time, but when he talked to tower they said GS was working fine. Does not know if akron followed up with a check of any kind.

Original NASA ASRS Text

Title: SMA HAS FALSE LOC SIGNAL, DSNDS BELOW FINAL APCH FIX XING ALT.

Narrative: FLT FROM YTZ TO CAK IN IMC OVER ENTIRE RTE, UNEVENTFUL UNTIL INBOUND FROM APPROX 18 MI OUT AND ON LOC, CAK RWY 23. CLRED FOR ILS 23 BY APCH AND DSNDED TO 3200 FT (MSL), AWAITING XING OM TO DSND TO MDA. HEARD OM AUDIO CLRLY (FRONT SEAT, NON-PLT PAX HEARD ALSO, ASKED WHAT THE BEEPING TONE MEANT) -- CONFIRMED ON HIGH SENSITIVITY. NO OM LIGHT INDICATION. SIGNAL INCREASED THEN DECREASED, AS IF PASSAGE OVER MARKER. AT THIS TIME, APCH HANDED ME OFF TO TWR. BELIEVING I HAD CROSSED THE OM, BEGAN DSCNT TO MDA. NO GS RECEPTION. CROSSED TRUE OM THEREAFTER, AURAL AND LIGHT INDICATION, ALT 2200 FT MSL, 1000 FT BELOW FINAL APCH FIX XING ALT. RPTED RECEIVING FALSE OM TO TWR BY PHONE AFTER LNDG. RESULT: NORMAL LNDG, NO MISHAP. COMMENT/ACTION: WILL HAVE ILS/MKB ELECTRONICS CHKED IN ACFT. ARPT WILL CHK ITS ILS EQUIP -- THEY HAVE HAD RPTS OF FALSE OM ON ILS 19, BUT THIS IS THE FIRST TIME ON ILS 23. IN FUTURE, IF UNCERTAIN OF POS (LIGHT BUT NO AURAL OR VISE VERSA, REMAIN AT ALT UNTIL SURE (CHK VIA VOR CROSS RADIAL OR RADAR) OR GO MISSED APCH, RATHER THAN GO BELOW A SEGMENT MINIMUM ALT UNTIL SURE OF BEING INSIDE FINAL APCH FIX. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES HE HAD ACFT CHKED AND A LOOSE ANTENNA COUPLING WAS DISCOVERED. HE BELIEVES IT WAS HIS EQUIP, NOT AKRON ILS THAT WAS THE PROB. GS WENT OUT AT SAME TIME, BUT WHEN HE TALKED TO TWR THEY SAID GS WAS WORKING FINE. DOES NOT KNOW IF AKRON FOLLOWED UP WITH A CHK OF ANY KIND.

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.