B737 flight crew missed turn onto ILS because of equipment malfunction.

Attributes
ACN	594271
Time
Date	200309
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : cvg.airport
State Reference	KY
Altitude	msl single value : 2500
Environment
Flight Conditions	VMC
Weather Elements	other
Light	Daylight
Aircraft 2
Controlling Facilities	tracon : cvg.tracon
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 18r
Flight Phase	descent : intermediate altitude descent : approach
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 125 flight time total : 8800 flight time type : 285
ASRS Report	594271
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : atp pilot : multi engine
Experience	flight time last 90 days : 140 flight time total : 11000 flight time type : 737
ASRS Report	594273
Events
Anomaly	airspace violation : entry non adherence : clearance non adherence : far other spatial deviation
Independent Detector	other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : executed missed approach
Consequence	faa : reviewed incident with flight crew other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

Arrival to cvg on radar vectors for ILS to runway 18R. Descent and approach checklists completed, ILS frequencys idented, approach control cleared us to descend to 2500 ft MSL (this was an unusually low altitude for approach into cvg) approximately 23 NM from the airport on an intercept heading for the localizer. We were then cleared to join the localizer and for the approach. As we proceeded we noticed flags in the localizer and GS indicators on the ADI and we both assumed our distance and low altitude were preventing us from receiving a good signal and we expected the signal to come up again any second. At 18 NM approach control asked us why we didn't join the localizer and gave us a 220 degree vector back to rejoin runway 18R localizer. Approaching 12 NM, we still had flags in localizer and GS and informed ATC we had equipment problems and went missed approach. On next approach we discovered that when VOR/localizer button on mode control panel was selected, the aircraft was dropping the ILS signal totally and the identify had a loud pitched tone and no identify. We continued and landed using a manually flown approach, without evacing the approach mode of the B737-200 flight control computer. The aircraft was written up on arrival cvg. 1) the aircraft malfunction led to an airspace violation, we crossed runway 18R localizer and went into runway 18L extended centerline at 18 NM. 2) we did not have any conflicts that we were aware of. 3) we made assumption that low altitude on vector (2500 ft) and long final 23-18 NM was reason we had flags. We should have asked ATC if ILS was monitoring correctly. 4) runway 18R does not have ADF and VOR is not located on field so it is very difficult/not possible to tell you are crossing localizer. Supplemental information from acn 594273: after our shutdown at the gate maintenance were summoned to investigate. They were able to emulate our problem. We discovered we were complacent during the intercept since there are no other reference navaids (ADF's, VOR field located). The only person with any 'big picture' was cvg final radar controller.

Original NASA ASRS Text

Title: B737 FLT CREW MISSED TURN ONTO ILS BECAUSE OF EQUIP MALFUNCTION.

Narrative: ARR TO CVG ON RADAR VECTORS FOR ILS TO RWY 18R. DSCNT AND APCH CHKLISTS COMPLETED, ILS FREQS IDENTED, APCH CTL CLRED US TO DSND TO 2500 FT MSL (THIS WAS AN UNUSUALLY LOW ALT FOR APCH INTO CVG) APPROX 23 NM FROM THE ARPT ON AN INTERCEPT HEADING FOR THE LOC. WE WERE THEN CLRED TO JOIN THE LOC AND FOR THE APCH. AS WE PROCEEDED WE NOTICED FLAGS IN THE LOC AND GS INDICATORS ON THE ADI AND WE BOTH ASSUMED OUR DISTANCE AND LOW ALT WERE PREVENTING US FROM RECEIVING A GOOD SIGNAL AND WE EXPECTED THE SIGNAL TO COME UP AGAIN ANY SECOND. AT 18 NM APCH CTL ASKED US WHY WE DIDN'T JOIN THE LOC AND GAVE US A 220 DEG VECTOR BACK TO REJOIN RWY 18R LOC. APCHING 12 NM, WE STILL HAD FLAGS IN LOC AND GS AND INFORMED ATC WE HAD EQUIP PROBS AND WENT MISSED APCH. ON NEXT APCH WE DISCOVERED THAT WHEN VOR/LOC BUTTON ON MODE CTL PANEL WAS SELECTED, THE ACFT WAS DROPPING THE ILS SIGNAL TOTALLY AND THE IDENT HAD A LOUD PITCHED TONE AND NO IDENT. WE CONTINUED AND LANDED USING A MANUALLY FLOWN APCH, WITHOUT EVACING THE APCH MODE OF THE B737-200 FLT CTL COMPUTER. THE ACFT WAS WRITTEN UP ON ARR CVG. 1) THE ACFT MALFUNCTION LED TO AN AIRSPACE VIOLATION, WE CROSSED RWY 18R LOC AND WENT INTO RWY 18L EXTENDED CTRLINE AT 18 NM. 2) WE DID NOT HAVE ANY CONFLICTS THAT WE WERE AWARE OF. 3) WE MADE ASSUMPTION THAT LOW ALT ON VECTOR (2500 FT) AND LONG FINAL 23-18 NM WAS REASON WE HAD FLAGS. WE SHOULD HAVE ASKED ATC IF ILS WAS MONITORING CORRECTLY. 4) RWY 18R DOES NOT HAVE ADF AND VOR IS NOT LOCATED ON FIELD SO IT IS VERY DIFFICULT/NOT POSSIBLE TO TELL YOU ARE XING LOC. SUPPLEMENTAL INFO FROM ACN 594273: AFTER OUR SHUTDOWN AT THE GATE MAINT WERE SUMMONED TO INVESTIGATE. THEY WERE ABLE TO EMULATE OUR PROB. WE DISCOVERED WE WERE COMPLACENT DURING THE INTERCEPT SINCE THERE ARE NO OTHER REF NAVAIDS (ADF'S, VOR FIELD LOCATED). THE ONLY PERSON WITH ANY 'BIG PICTURE' WAS CVG FINAL RADAR CTLR.

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.