Several years ago, I was flying from the USA to Buenos Aires. That's a very long flight, and it was overnight for us. When I woke up it was early in the morning and we were over Argentina. I don't remember exactly what the plane was, but it was a very large jet. 767 or something like that.
As we got close, the pilot came on the intercom and announced that it was too foggy down below to land, but we still had plenty of fuel reserves left and so he was going to fly in circles for a while and see if the rising sun didn't burn off some of the fog. After about 15 minutes, he came on again and said that the fog was burning off, and we were about to begin our descent into Buenos Aires.
I was in a window seat, and I looked outside. We went into a cloud... and never came out. Literally the first clue I had that we were anywhere near the ground is when I felt the wheels hit the runway. And to this day I've always wondered what in the world was going on in the cockpit.
I don't care how good the pilot's eyes were; there was zero visibility outside that airplane. That fog we were in was the metaphorical "pea soup", and he could not possibly have landed visually. But we came down safe, exactly where we were supposed to be, which means he must have made some sort of instrument-guided landing. But if he was capable of making a perfect instrument landing at that runway all along, why was the fog reducing visibility ever a concern in the first place?
Does anyone here have enough experience to explain what happened that morning?