IO540,
To put it in simple words;
A non-FM immune ILS or VOR system is U/S. Put another way, it no longer meets the required standard for it to be used as intended.
It is not sensible or legal to use U/S equipment as a sole source of navigation information on an IFR flight.
What you say about the fuel issue is totally true and an unnecessary shoddy practice in this age.
Then, close down all flying schools. They train with non-FM VORs all the time Reference please for the words "legally U/S".
No. I said that there is nothing wrong with this
provded that another appropriate way to confirm the position of the aircraft is available. You will find that most of those schools will do the IMC training in VMC and in visual contact with the surface.
You could very rightly say that charging someone a sum of money to do IMC radio navigation training with U/S equipment which legally can not be used as intended is not providing value for money.
Filters are relatively cheap and are a simple mod. They should have been fitted long before now. Perhaps EASA will replace the CAA bumbling with a simple sticker - U/S due Non-FM immune.
Please feel free to try and convince us that relying on U/S equipment is sensible.
Regards,
DFC