[time-nuts] Aircraft ping timing

[Jim Lux]

On 3/20/14 12:07 AM, Poul-Henning Kamp wrote:
> In message <279331507.5734621395275538874.JavaMail.actor at webmail5>, "iovane at inw
> ind.it" writes:
>
>> My question was on what would be the expected accuracy of the circle's radius.
>
> Projected onto the surface of the earth, the uncertainty leaves a band
> approx 740km wide.
>

Is there a document that describes the system somewhere?  I've seen 
various descriptions of what's going on. Do they use timing or amplitude 
measurements?