Overwing, interesting you call it that way, because that's pretty close to the way the HIAA sees it. Here's a quote from the Chronicle Herald (our local newspaper) today: "Although a HIAA spokeswoman said earlier Friday evening that 'significant delays' were the result of heavy fog and runway upgrades, it was the poor weather that caused the biggest problem for travellers. 'Our operations people have told me that the fog is so thick they would expect delays, regardless if we had our instrument landing system,' Gina Connell, aiport authority spokesperson said about 10 pm Friday. 'There's no way they would have landed.'"

I took that with a grain of salt ... I've flown into YHZ bi-weekly for years and never had a go-around or a diversion due to fog; this stuff we have right now is thick, but it's not uncommon.