GalaxyFlyer wrote:Because it knows there’s a runway in front of it and using GPS knows where it is in relation to that runway. Just try landing at an airport that’s NOT in the database. It warned you unless you construct a pilot defined waypoint as the airport. Yes, I’ve had to do that.
Woodreau wrote:There's two basic systems - GPWS and enhanced GPWS.
the basic GPWS relies solely on the radar altimeter and guards against 7 different modes:
Excessive descent rate ("SINK RATE" "PULL UP")
Excessive terrain closure rate ("TERRAIN" "PULL UP")
Altitude loss after take off or with a high power setting ("DON'T SINK")
Unsafe terrain clearance ("TOO LOW – TERRAIN" "TOO LOW – GEAR" "TOO LOW – FLAPS")
Excessive deviation below glideslope ("GLIDESLOPE")
Excessively steep bank angle ("BANK ANGLE")
Windshear protection ("WINDSHEAR")
Enhanced GPWS adds a virtual terrain database paired with aircraft position.
So when you're approaching to land, the aircraft knows you are in proximity to a landing runway and as long as you are above the terrain clearance floor, there is no terrain warning.
aeropix wrote:Since everybody already gave complete and accurate answers, I will just make a small comment about the thread title: "GPWS" stands for "Ground Proximity Warning System" so the title of the thread translates to "Ground Proximity Warning System System".
I won't say it's right or wrong, even though I have my opinion. Just pointing it out for your own consideration. Something like,
"GPS System" that I hear often = "Global Positioning System System"
"ATM Machine" = "Automated Teller Machine Machine".
I'll leave it up to you to decide if that sounds correct, or should perhaps be just "GPWS" with no "extra" "System" or maybe use "GPW System".
Or leave it as is, your call.
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