Air New Zealand ILS Problem : LUSENET : Grassroots Information Coordination Center (GICC) : One Thread

Flight International

Meanwhile, it remains an eternal truth that, just when you think you know all about a well- established system, you find out something you didn't know. Because a member of an Air New Zealand (ANZ) Boeing 767 crew was monitoring raw data as well as the instrument landing system (ILS) indications during an approach to Apia, Western Samoa, he could see that in that case the ILS was showing the aircraft on glidepath when it clearly was not, yet there were no warnings of signal orinstrument faults.

As ANZ has since observed, if their 767 had crashed there would be no indication of any ILS or system error, so the crew would have been blamed. ANZ has since studied an anomaly in ILS indications that can occur while the ground equipment is being maintained, and believes that this is what might have happened to the Korean Air crew in the crash at Guam in August 1997. Not only that, but ANZ believes that up to 40 controlled flight into terrain accident reports warrant review in the light of its experiences - which other airlines have also reported. If ANZ is right, this is another area in which tragedies need not recur, because any alert crew could recognise this ILS "trap".

-- Rachel Gibson (, July 25, 2001

Moderation questions? read the FAQ