Ian W:
"The pings carry the ID of the sender - that is how INMARSAT know what to do with the ping, reject it or accept it and what level of service it should get. If you get a cell phone and turn it on - the first thing it does is start pinging the networks with its IMEI - the networks that do not service that phone take no notice the ones that do respond. So in this case no ACARS data but electronic identity data."
This post implies that the AIRCRAFT initiates the ping.
Other posts have stated that the SATELLITE initiates the ping.
Obviously both can't be right. The pings seem to be a critical part of the information available right now.
Can someone with firsthand knowledge of SATCOM/ACARS architecture help us out here?
Assuming the ping data for MH370 are Kosher (Halal?), how 'accurate' are the range/distance estimates (aka the red arcs) that have been generated?
Are we talking +/- 10km? 50km? 200km?