On Sep 5, 10:21 pm, wrote:

I have a APRS tracker that continuously sends position/velocity info
on the ham frequency.

This happens to be a topic near and dear to my uber-geeky heart. On
the one hand we have ELTs, which *hopefully* kick off when a plane
crashes. If it isn't damaged in the crash . . . if the batteries are
still good . . . if the antenna leads stay attached . . . etc. On
the other hand we have a system that is designed to tell you where the
plane is at all times, and hey, if the guy doesn't come home--play
back the recorded position data and go look in the area where the
signal stopped.

--Air-side cost . . . compared to an ELT, the things are quite
reasonable. Compared to a 406 ELT, they're peanuts.
--Ground-side cost . . . the ground side would need to get built--I
would speculate that a receiver/recorder per ATC sector would do
nicely. You could build the ground side for the entire nation for
next to nothing (when measured by gov't standards). There are guys on
this group, right now, that could design and deploy the whole ground
side without even thinking hard.
--Position data recording . . . compared to what a TIVO packs away,
setting up a system to record, say, the last 72 hours worth of
reported positions for airplanes in a given region is pretty darn
approachable. Lat/Lon, speed & altitude. That is not a lot a data.
Don't even record all of it, just record 5 minute intervals or
similar. Get fancy and make the intervals speed-sensitive. It's just
software on a PC, darn it. The amount of data is so small you could
do this on the computer the average junior high kid threw away last
week.
--Traffic avoidance . . . not only could your little ground recorder
get the signal, by golly other planes could too. Be a nice cheap way
to have live traffic in the cockpit without the ADS-B expense,
complexity and hassle.
--No electrical system? Guys at my airport without starters and
alternators are still using a little 12v batt for a radio.
--This system is a bit similar to something commercial shipping has
started doing. It's a transponder system for shipping, but instead of
being assigned a different squawk every time they go out, the have a
permanently assigned squawk. N-number anyone?
--Change the freq so you don't need the Ham ticket.

This stuff breaks my heart. It would be so simple, so cheap, so
effective, it might actually save a life (over and above the poor
track record ELT's have) and it ain't never going to happen. No one
will make money off it so no one will advocate it. I have to go for a
walk to calm down.

Stay safe, folks.

Steve.