One of my favorite KML collections from the early days of Google Earth (way back in 2005 – which is a long time in Internet time), was the real-time flight tracker by FBOweb that lets you watch incoming aircraft for several major airports in the US. I am a bit disappointed they haven’t enhanced the tracker very much considering all the new features in Google Earth since 2005. But, it still amazes people when I demonstrate live updating positions of planes in 3D approaching a major airport. (See a list of several cities to follow in this post).
Recently I ran across another real-time flight tracker in the Netherlands for Google Earth. The Geluidsnet web site (in Dutch) lets you watch planes arriving and departing from a few airports through this Google Earth network link 
(once it loads, click on “Schiphol area” to see the tracks for the last 30 minutes). They display a vertical “fence” below each plane to help visualize the altitude and paths. Orange fences are arriving aircraft, green are departing. The visualization gives a better sense of position and the number of planes when viewed from an angle. If you look closely, you will notice every few seconds the positions (and fences) change. Updating data like this is done using the power of the Google Earth “network link“.
You would think the data is coming from aircraft transponders. [UPDATE 1530 ET: And they are! In doing a translation of a page on the Dutch-speaking site, I read how they were taking sound measurements for noise pollution purposes related to aircraft – and interpreted this to mean that was how they were getting the data. But, locals have explained to me the data is in fact coming from transponders.]
About Frank Taylor
Frank Taylor started the Google Earth Blog in July, 2005 shortly after Google Earth was first released. He has worked with 3D computer graphics and VR for many years and was very impressed with this exciting product. Frank completed a 5.5 year circumnavigation of the earth by sailboat in June 2015 which you can read about at Tahina Expedition, and is a licensed pilot, backpacker, diver, and photographer.
Can you point exactly where you read that they are using acoustic measurements to determine the aircraft positions? I find that very hard to believe. Simple ADS-B receivers are fairly cheap and they does the trick exactly.
@Timo: Here is the page where I read about how they gathered the data – I may have misinterpreted the translation, but it appears they are using sound technology for environmental purposes and the resulting data is being processed to determine the information on the planes.
http://www.geluidsnet.nl/geluidsnet/over-geluidsnet/
From that Dutch website, I understand that the main purpose of that organisation/website, is measuring the “noise pollution” of the air traffic, so that’s what they are measuring. OTOH, the part that’s much more interesting for most Google Earth enthousiast, i.e. following the path of the plane is taken from the transponder RF signals sent by the aircrafts. So, two very different things I believe. Hey, now I can see which planes pass over my house!
[I am an native Dutch speaker (from Belgium)]
I too liked to monitor the Flight Tracker. However, what I really liked was listening to the air traffic controllers at locations like Atlanta it was constant chatter. I’m amazed at how they do their job.
With this rate of improvement in Google earth, I believe in no time they would be able to provide simulation modes. Its just a beginning with 3D flight tracking.
The information is from the planes beacons indeed, for the technique, see: http://en.wikipedia.org/wiki/Transponder_%28aviation%29
Since they log all info, you can also view the flightpath of the crashed Turkish Airlines flight on February 25th of this year, http://www.geluidsnet.nl/fileadmin/publicaties/radar.vlieghinder.nl_en_geluidsnet.nl_TK1951_track.kml
For info on the crash: http://edition.cnn.com/2009/WORLD/europe/02/25/turkish.plane.amsterdam/index.html
The site itself is actually not plane-minded, but more for generating evidence and insight into the problems of noisepollution. Previously data was only sparsely available and grossly aggregated, making it hard to plead your case with.
I understood it in the same way, they are making studies how air traffic is affecting the noise pollution. I am pretty sure that they are capturing the ADS-B messages sent my airliners. Same kind of application can be seen from http://www.flygradar.nu/
Is there a way to actually fly the KML file I upload to Google earth on the same plane/altitude as the track? I haven’t been able to do this but it would be a great feature!