NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: MH370 circle of position?
From: Peter Monta
Date: 2014 Mar 15, 08:56 -0700
From: Peter Monta
Date: 2014 Mar 15, 08:56 -0700
This language is not precise enough to infer much, but one interpretation is that the aircraft system was reporting on the angle from the Inmarsat bird to the local horizon.
Or rather, we're seeing the estimates of angle between aircraft signal and the nadir of the Inmarsat satellite. It sounds like this process is an acquisition aid for the aircraft's antenna: the aircraft emits these pings, perhaps with a low-gain or omni antenna, and then the Inmarsat infrastructure computes an angle-of-arrival and sends that back to the aircraft, allowing it to speed up the search for alignment of its high-gain antenna.
I would have thought GPS could directly provide the aircraft's absolute attitude without all this handshaking, but perhaps it was desired not to have a GPS dependency.
Cheers,
Peter
Peter
