B747 FIRST OFFICER REPORTS ERRATIC ILS AND GS INDICATIONS DURING APPROACH TO DNMM; RESULTING IN MISSED APPROACH THAT NARROWLY MISSES THE CONTROL TOWER.

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DURING APCH TO LAGOS (DNMM) ARPT IN IMC CONDITIONS; WE SUDDENLY EXPERIENCED FLUCTUATING LOC AND GS INDICATIONS AT THE SAME TIME AS BREAKING OUT. IT FIRST SEEMED THE ILS WAS NOT BEING PROTECTED THEN MORE LIKE IT WAS FAILING. FO (ME) STARTED TO LEVEL OFF AND INITIATE A GAR BUT CAPT WAS EXERTING FORWARD PRESSURE ON YOKE. I THOUGHT HE HAD THE ARPT IN SIGHT AND ANNOUNCED 'YOUR ACFT.' AFTER I DID SO I SAW THE RWY OFF TO THE L AND STATED 'GAR; GAR.' I ASKED IF HE WANTED FLAPS 20 DEGS WHICH HE ACKNOWLEDGED. TWICE I STATED 'POSITIVE RATE' AND HE THEN CALLED FOR THE GEAR AND WE WERE ESTABLISHED IN THE CLB. I DID NOTIFY TWR OF THE GAR AND RECEIVED INSTRUCTIONS TO THE VOR FOR A NEW APCH. AFTER CONTINUING TO THE VOR WE CONDUCTED A SUCCESSFUL APCH AND LANDED. IN THE BLOCKS ANOTHER ACFT ASKED THE TWR TO VERIFY WHAT INDICATIONS WE HAD AS THEY ALSO EXPERIENCED WILD FLUCTUATIONS OF THE ILS SYS. WE BLOCKED IN AND WERE REQUESTED TO COME TO THE TWR. THE CAPT; ALONG WITH A SECOND CAPT AND 1 FO; WENT TO THE TWR WHILE I REMAINED WITH THE SHIP. A WRITTEN RPT WAS REQUESTED DUE TO THE PROX OF THE LOW APCH WITH THE TWR AND IT WAS WRITTEN BY THE CAPT IN THE SEAT AND RETURNED TO THE OFFICIALS. WHILE ON THE GND A COUPLE MORE ACFT EXECUTED LOW APCHS AND GAR'S AND THE ARPT DID CONDUCT FLT CHKS ON THE ILS. IT SHOULD BE NOTED THAT ON A PREVIOUS FLT 1 WK EARLIER ATC COMPLETELY DISAPPEARED FOR APPROX 10 MINS AND THE FIELD BECAME TOTALLY UNCTLED. THE VOR APPEARED TO BE OTS AS USUAL AND THE LEVEL OF ATC PROFICIENCY IS LOW. THIS IS A VERY DANGEROUS AIRFIELD TO OPERATE IN OR OUT OF AT ANY TIME. THE MINIMUMS ON THE ILS ARE 400 FT AS I RECALL AND THE FIELD ELEVATION IS 135 PLUS WHATEVER THE TWR/BUILDINGS ARE.