Originally Posted by
TangoAlphad
Then the aircraft is unlikely to carrying out Cat 2 ILS's..
As with all things, you can't write to cover all eventualities however most aircraft shooting an instrument approach at an airfield with a tower are likely to have a flight plan. If it doesn't and a controller suspects they are busting minima I'm sure they have a procedure to follow state depending and if the aircraft is commercial or not.
Few helicopters fly airways on an IFR flight plan but it's by no means unusual to carry out ILS approaches to airports where RVR is measured.