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A B727-200 making an approach into dkr, senegal, has the ILS self test switch stuck in the down right position. Flight crew follows this false indication resulting in disorientation and cftt.
| Attributes | |
| ACN | 397475 |
| Time | |
| Date | 199803 |
| Day | Mon |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : dkr |
| State Reference | FO |
| Altitude | agl bound lower : 500 agl bound upper : 500 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tower : dkr |
| Operator | common carrier : air carrier |
| Make Model Name | B747-100 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | descent : approach |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 110 flight time total : 14000 flight time type : 5000 |
| ASRS Report | 397475 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 250 flight time total : 13000 flight time type : 3000 |
| ASRS Report | 397837 |
| Events | |
| Anomaly | aircraft equipment problem : critical other spatial deviation other spatial deviation |
| Independent Detector | other flight crewa other other : unspecified cockpit |
| Resolutory Action | flight crew : became reoriented flight crew : overcame equipment problem flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Dual (and unrelated) failure of aircraft ILS equipment resulted in an off track approach and flight over populated area at 500 ft AGL. Missed approach at 500 ft AGL, followed by a visual approach to a normal landing. Captain's ILS was stuck in 'self test' mode indicating 1/2 to 1 DOT high, 1/2 to 1 DOT left of course (ie, commanding fly down and fly right). Attempting to correct on course, crossed the coastline at about 500 ft, saw buildings but still no runway in sight, felt something was wrong, missed the approach (ie, executed a go around). This took us back near the final approach fix. Asked first officer to confirm ILS frequency/course and identify -- he reported no aural identify. I turned toward the airport (using VOR), asked the tower to turn on the runway lights (it was now dark) and the runway instantly became visual. Contributing factors: 1) the ILS procedure is a DME arc to the localizer: after crossing the 'lead- in' radial, an intercept heading is taken, the ILS frequency for both sides must be tuned, the inbound course must be set on both sides, the navigation mode selector is placed in ILS, and the aircraft confign must be changed (flaps/gear) and the tower must be called. All this leaves no time to properly identify the ILS. 2) the runway lights were not on during the first approach (it was just getting dark, dusk is a very difficult time to pick out a non-illuminated runway). 3) as the WX was VMC, and as he had a GS flag on his side (the second failure), the first officer spent 90% of his time outside looking for the airport. 4) the ADF RMI was in a non standard spot on the panel on this particular aircraft making it difficult to include in the instrument scan. Human performance considerations: 1) expecting to see the runway shortly after intercepting the localizer strict instrument procedures were not followed, including standard callouts. 2) an uneasy feeling that 'something's not right' is an important feeling to listen to. 3) after landing an entry was not made in the maintenance log because I felt certain the problem was with the ground equipment. Both ILS receivers tested normally, both radios received properly on all vors during the flight, no identify was received on the ILS frequency -- and ground equipment in so called 'third world' countries is often suspect. I was wrong, I found out, as on the next leg (flown by another crew) the same indications occurred on the ILS. Supplemental information from acn 397837: I knew from same approach 2 days prior, we were not where we should be, runway still not in sight, captain initiated missed approach, straight ahead. Flew over unlighted area, and found airport, still unlit. Captain HSI showed fly right, fly down indications when visually checked in slot. Both ILS checked on ground before, and after flight checked ok. We later found out #1 ILS had stuck in test mode while in flight. That's why no identify with good ground facility. We initially thought ground facility was at fault.
Original NASA ASRS Text
Title: A B727-200 MAKING AN APCH INTO DKR, SENEGAL, HAS THE ILS SELF TEST SWITCH STUCK IN THE DOWN R POS. FLC FOLLOWS THIS FALSE INDICATION RESULTING IN DISORIENTATION AND CFTT.
Narrative: DUAL (AND UNRELATED) FAILURE OF ACFT ILS EQUIP RESULTED IN AN OFF TRACK APCH AND FLT OVER POPULATED AREA AT 500 FT AGL. MISSED APCH AT 500 FT AGL, FOLLOWED BY A VISUAL APCH TO A NORMAL LNDG. CAPT'S ILS WAS STUCK IN 'SELF TEST' MODE INDICATING 1/2 TO 1 DOT HIGH, 1/2 TO 1 DOT L OF COURSE (IE, COMMANDING FLY DOWN AND FLY R). ATTEMPTING TO CORRECT ON COURSE, CROSSED THE COASTLINE AT ABOUT 500 FT, SAW BUILDINGS BUT STILL NO RWY IN SIGHT, FELT SOMETHING WAS WRONG, MISSED THE APCH (IE, EXECUTED A GAR). THIS TOOK US BACK NEAR THE FINAL APCH FIX. ASKED FO TO CONFIRM ILS FREQ/COURSE AND IDENT -- HE RPTED NO AURAL IDENT. I TURNED TOWARD THE ARPT (USING VOR), ASKED THE TWR TO TURN ON THE RWY LIGHTS (IT WAS NOW DARK) AND THE RWY INSTANTLY BECAME VISUAL. CONTRIBUTING FACTORS: 1) THE ILS PROC IS A DME ARC TO THE LOC: AFTER XING THE 'LEAD- IN' RADIAL, AN INTERCEPT HEADING IS TAKEN, THE ILS FREQ FOR BOTH SIDES MUST BE TUNED, THE INBOUND COURSE MUST BE SET ON BOTH SIDES, THE NAV MODE SELECTOR IS PLACED IN ILS, AND THE ACFT CONFIGN MUST BE CHANGED (FLAPS/GEAR) AND THE TWR MUST BE CALLED. ALL THIS LEAVES NO TIME TO PROPERLY IDENT THE ILS. 2) THE RWY LIGHTS WERE NOT ON DURING THE FIRST APCH (IT WAS JUST GETTING DARK, DUSK IS A VERY DIFFICULT TIME TO PICK OUT A NON-ILLUMINATED RWY). 3) AS THE WX WAS VMC, AND AS HE HAD A GS FLAG ON HIS SIDE (THE SECOND FAILURE), THE FO SPENT 90% OF HIS TIME OUTSIDE LOOKING FOR THE ARPT. 4) THE ADF RMI WAS IN A NON STANDARD SPOT ON THE PANEL ON THIS PARTICULAR ACFT MAKING IT DIFFICULT TO INCLUDE IN THE INST SCAN. HUMAN PERFORMANCE CONSIDERATIONS: 1) EXPECTING TO SEE THE RWY SHORTLY AFTER INTERCEPTING THE LOC STRICT INST PROCS WERE NOT FOLLOWED, INCLUDING STANDARD CALLOUTS. 2) AN UNEASY FEELING THAT 'SOMETHING'S NOT RIGHT' IS AN IMPORTANT FEELING TO LISTEN TO. 3) AFTER LNDG AN ENTRY WAS NOT MADE IN THE MAINT LOG BECAUSE I FELT CERTAIN THE PROB WAS WITH THE GND EQUIP. BOTH ILS RECEIVERS TESTED NORMALLY, BOTH RADIOS RECEIVED PROPERLY ON ALL VORS DURING THE FLT, NO IDENT WAS RECEIVED ON THE ILS FREQ -- AND GND EQUIP IN SO CALLED 'THIRD WORLD' COUNTRIES IS OFTEN SUSPECT. I WAS WRONG, I FOUND OUT, AS ON THE NEXT LEG (FLOWN BY ANOTHER CREW) THE SAME INDICATIONS OCCURRED ON THE ILS. SUPPLEMENTAL INFO FROM ACN 397837: I KNEW FROM SAME APCH 2 DAYS PRIOR, WE WERE NOT WHERE WE SHOULD BE, RWY STILL NOT IN SIGHT, CAPT INITIATED MISSED APCH, STRAIGHT AHEAD. FLEW OVER UNLIGHTED AREA, AND FOUND ARPT, STILL UNLIT. CAPT HSI SHOWED FLY R, FLY DOWN INDICATIONS WHEN VISUALLY CHKED IN SLOT. BOTH ILS CHKED ON GND BEFORE, AND AFTER FLT CHKED OK. WE LATER FOUND OUT #1 ILS HAD STUCK IN TEST MODE WHILE IN FLT. THAT'S WHY NO IDENT WITH GOOD GND FACILITY. WE INITIALLY THOUGHT GND FACILITY WAS AT FAULT.
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.