Originally Posted by
Denti
And that is why there is the Terrain Inhibit switch, to silence those many nuisance warnings you get if flying around with an old database.
Or,you could be using terrain inhibit for valid databases but warnings that are unavoidable for landings at certain airports, usually mountainous. I used to fly into a couple of airports that had close in high terrain, one of which gave occasional Terrain alerts and the other one that gave alerts every time. As this was in the visual segment of an approach, the company procedure was to select Terrain Inhibit. Keep in mind that not all alerts are inhibited when this is done so if you are coming in close over a hill or cliff and get too close, you still get an alert.
The other situation was arriving at a relatively flat airport but with an open pit mine on short final with the aircraft at about 500 feet above airport elevation. The radar altimeter would suddenly increase several hundred feet as we passed over the deep mine and then have a sudden closure rate as we crossed over the far edge of the mine. The sudden decrease in radalt altitude triggered a terrain warning that could not be cancelled.