Pilot flying/handling pilot must fly the approach with only sole reference to the ADF.
I guess whoever wrote the ops manual is really proud of that. Lenin (living in the same era) would have been proud of him - except Lenin was a lot more pragmatic.
The non flying pilot/pilot monitoring is however allowed to display the FMS overlay on their own individual EFIS display....purely to monitor the ADF/FMS tracks and call out any discrepencies that may be apparent.
And of course if the ADF says you are OK but the FMS says you are all going to die, the FMS is disregarded.
