Comment Google needs to look at itself!! (Score 4, Interesting) 117
Guess who is my ad provider? Google AdSense.
Google, heal thyself.
You're missing the point. The idea behind GPS-driven ADS-B is that it REPLACES surveillance radar.
Here's how it works right now: The ground-based radar sends out a signal; it hits the aircraft and bounces back; ATC now knows which direction and how far away the aircraft is. On top of this, there is a transponder in the aircraft which sends back a coded number assigned by ATC, so that ATC can determine which dot on their radar screen is which aircraft. Additionally, if the transponder has (and has enabled) Mode C (which is required in most congested airspace), it sends back the aircraft's altitude. ATC now has a 3-dimensional fix on the aircraft, with positive verification as to who you are.
ADS-B gets rid of all of this. Instead, the aircraft has a GPS receiver, which gives itself a 3-dimensional fix in space. It transmits this information along with a unique identifier, when interrogated, to ATC. ATC utilizes this information to identify and track the aircraft in 3 dimensional space, as is now done with conventional radar/Mode C.
The problem is, what if GPS goes out? What if some pimply 17 year old kid buys a GPS jammer from Mexico and sets it up on his roof? Every aircraft in the area suddenly loses their ability to receive GPS signals, and all of a sudden ATC has no idea where any of the aircraft are. There is no backup system, because part of NexGen is the decommissioning of all primary surveillance radar.
THAT is the issue.
Nothing succeeds like excess. -- Oscar Wilde