Our SOP says:-
The APPR pb shall not be pressed until:
• The ILS is tuned and identified.
• Clearance for the approach has been received.
• The aircraft is on an acceptable intercept heading.
• Raw data confirms correct sensing.
• The aircraft is not laterally displaced to the extent that a false capture may occur.
Certainly 25 nm ICAO ILS protection zone is to be observed.
VR
