I was just wondering if anyone here has encountered significant tangible errors regarding certain conventional navigation systems as we read in the books.

Polarization error - regarding the VOR, NDB, and LOC has anyone here seen any significant effects while using these systems with high angles of bank and/or pitch? If so, what were the effects?

Propeller modulation error - regarding the VOR, has anyone here seen the effects of this error? If so what were the effects and what was the RPM range?

FM interference - regarding the LOC (and perhaps the VOR as well), has anyone seen this interference from commercial broadcast stations? I recall some time ago there was a mandate in Europe to install FM immune receivers....I don't believe your typical bendix/king nav radio in the US is FM immune but I could be wrong.

Quadrantal error - regarding the NDB, has anyone seen the effects of this error, and if so what are they?