On Mon, 03 Mar 2008 18:31:05 +0000, Jim Logajan wrote:

I just did a quick scan of the DoD comments posted today
(FAA-2007-29305- 0154.1) and it looks like they are complaining about
the cost or unlikelyhood of retrofitting some of their aircraft to be in
compliance. Hmmm.

And those are real issues. I wish there was some magic wand to wave to
drop the price.

[...]
Nit: I'm not clear how transponders in two otherwise NORDO aircraft
stops either from bumping into each other. Or to what extent transponder
(or ADS- B Out) equipped aircraft prevent MACs near or at non-towered
airports.

You're right that the benefit is limited to the owner that chooses to do
the minimum. That's the bad side of this. But it's the "cost" of having
owners foot the bill for building this "network", I'm afraid.

One alternative to this would be to mandate -IN as well as -OUT. I'm
glad that that's not being done, in that it gives the owner more choice.
To my mind, the mandate covers the minimum necessary to build the network
that makes the benefits available to anyone taking the next step. W/o
the mandate, that benefit would be far more limited.

Separate from this, the GA owner can choose whether or not to spend the
extra dollars to gain direct benefit from this network.

My understanding is that if they want to fly VFR above 10,000 MSL they
will be required to have ADS-B Out. This is a _new_ cost requirement for
using that portion of the airspace - even to VFR flights. Not only is it
a new cost, it provides the VFR pilot no benefit.

That is true. But as I've written, this mandate is necessary so that the
benefit of ADS-B-IN be available. That's why I compare this to
transponders: it provides benefit to aircraft participating in
transponder-in (ie. taking to ATC {8^) but an aircraft can choose to not
participate.

- Andrew