Mode S radar identification
In the UK, MATS Part 1 Section 1: Chapter 6: 5B appears to allow
"direct recognition of the [Mode S] Aircraft Identification Feature on the situation display [to] be used to establish surveillance identification, subject to either:
(1) correlation of the Aircraft Identification Feature with the aircraft identification entered in the flight plan and displayed to controllers on flight progress strips; or
(2) correlation of the Aircraft Identification Feature with the aircraft’s callsign used in a directed RTF transmission to the controller."
I had Southend do precisely that the other day:
"Southend, G-XXXX request traffic service"
"G-XXXX, Southend, identified, traffic service, pass your message"
However on departing Cambridge and changing to Stansted/Essex, I'm still asked to squawk ident.
I'm curious to know why "direct recognition" is not used by TC in those circumstances, and also whether Mode S alone is used for radar identification in this way in other states.