concerned about misconceptions
I fly in the USA. We use slightly different terms and measures.
Generally speaking:
CAT 1 ILS approaches require 1/2 mile visibility...this can be slightly reduced with better approach and runway lighting. It is against the rules to start an approach if the weather is reported below minimums. I can only imagine that the metroliner had received word that the wx was at or above minimums when they started the approach.
even though some of the published metars might indicate below minimums, fog can change so quickly that values might be reported from the control tower that have not yet reached the media. indeed attempting approaches to opposite ends of the same runway indicates knowledge of local wx phenomenoa and is something I would attempt at many airports.
There is so much talk about 3 approaches. The only thing that really matters is if the fatigue of making so many approaches has taken its toll on the pilots and if the fuel is starting to demand diversion to a safe alternate airport. While some airlines may actually have it in their rules (flight ops manuals), one simply shouldn't read too much into this...
Except when there is a condition known by the slang term: Get There ITIS (as in laryngitis). Sometimes, (and I AM NOT SAYING THIS TIME) you can want to get some place too badly and you try too hard...perhaps ,and I say again PERHAPS, bending the rules slightly. Again, I don't know if that is the case in this situation.
The metroliner most likely is not equipped for coupled autopilot approaches. At least mine were not. Maybe this one was, maybe not. The metroliner is an adequate if not deluxe sort of plane. I would rather drive a rolls royce than a honda civic...but both will probably get you there just fine. Same sort of thing with the metroliner...and it aint' no rolls.
The engines on this type are just fine. While I mentioned the NTS system, its not a big deal, just an interesting thing to pilots who have flown different type engines.
Now, what can go wrong? What caused this crash?
I will say that landing a plane in foggy conditions is very demanding upon the crew. Mistakes can be made. As some have said, it is possible to see an airport's runway 10 miles away, but the last 20 feet it can vanish in fog. I've had this happen and boy, it gets your attention fast. It is also possible to over control or over compensate if you are off the exact centerline of the runway. You've just been ''on instruments'' and now must quickly transition to visual cues, cues that can be obscured by the fog. I still think about some less than perfect maneuvering near the end of an instrument approach in my own flying. And that was over 20 years ago. It never got close to clipping a wing tip, but it wasn't as gentle as I would have liked.
A myriad of mechanical problems could have happend...but probably didn't. There is more than one attitude gyro for example, the plane is flyable on one engine...though engine out ops are demanding, especially at low altitude.
The discipline in the cockpit for an instrument approach is very demanding. I do not have any access to the training methods of this airline. But I've flown for 3 small airlines and one big airline. The big airline did it right, one of the three small airlines did it right (of course they were the first to go out of business...doing it ''right'' costs money) the other two airlines didn't do a good job of training.
So...I think they started each and every approach ''legally''. That the number of approaches, except as outlined above, doesn't matter.
What happened? We need more information and I'm sure the authorities will do an honest job of finding out.
But we should, as pilots and interested observers, continue to have discussions of how to improve our own flying.