In article ,
Andrew Gideon wrote:

The mode S based system, if memory and gossip serves, exists only as a
cost-savings device for the airlines (though I admit I don't quite see
how...unless they've already invested in mode S; have they?).

The airlines already have Mode S (it's a required component of TCAS II).
Cargo aircraft are also being equipped with Mode S.

--
Bob Noel
(goodness, please trim replies!!!)