But they don't require 7700 for that, surely? I mean, if a CAS controller sees a 7000 squawk heading directly for his/her airspace, wouldn't he/she start planning for an infringement already?
7700 flashes, 7000 doesn't. With the advent of moving map GPS you see a lot of 7000's coming up to the edge of CAS then sliding down the side. 7700 accentuates the "rogue" element of the track.
Does D&D have nationwide radar coverage? I though they did VDF triangulation?
Once upon a time yes, but they also have access to all of the NATS en-route radar network.
DuchessDriver - feel free to look at my profile first before teaching me to suck eggs
The whole point about being lost is you DON'T KNOW where you are, you dont know who's CAS you may have infringed (I've been involved in an aircraft lost scenario where the aircraft was 50 miles away from where they thought they were). 121.5 is a single point of contact who will liaise and co-ordinate, effecting transfer of control if necessary, to the relevant ATC unit.
Yes, I will be avoiding any infringer . However, by squawking 7700, and calling 121.5 you can be pinpointed accurately AND SPOKEN TO whilst D&D carry out the above actions. The squawk isn't for my benefit as an ATCO, it's for the lost aircrafts benefit in being quickly located.