alt Hacker NewsAirline captain here... A visual approach to an airport in mountainous terrain on a moonless night is very risky.
In our operation, departing to an airport with missing weather reports would not be permitted, so in a Part 121 scheduled service this flight may not have been able to dispatch legally.
Airliners have DME/DME triangulation which allows them to achieve area navigation (RNAV) without GPS. The interference would have precluded a GPS approach but may have left the GPWS ("Terrain! Terrain!") alerts unaffected.
In this case the ILS was not available, but only because the local altimeter setting was not available. In this case I could accept a visual approach, but use the ILS to provide lateral and vertical guidance towards the runway.
There are many things I have learned about flying from years at the airlines that I would have had to learn the hard way at a Part 135 or Part 91 operation. One of those things would have been when to say "no".
Take the airplane to a mountainous airport with missing weather reports at night with NOTAM'd GPS interference? No.
Do a visual approach on a moonless night with no GPS for terrain awareness? No. Fly the ILS even if it's NOTAM'd out.
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Would using the ILS without the local altimeter actually be a safe way to land the plane? (Ignoring whether or not ATC is allowed to give you clearance for that.) Is the requirement of a local altimeter just overly cautious?
It was hammered into me that moonless nights could be as or MORE dangerous to me than flying into weather - at least when you fly into a cloud you KNOW you're fucked.