Originally Posted by
Just This Once...
RVSM compliance et al - if you are shepherding an airliner or just intercepting one it is best if you don't break the congested & carefully choreographed airspace by introducing a non-compliant aircraft to the mix.
As for 1435 Flt they were not Tranche 1 jets in my time, even from the start of the transition from F3. It could have happened since of course but it was never the plan.
Nothing to do with Tr1 vs RVSM compliance.