Must...Fly!, I was looking at the Metair forecasts a few minutes ago and deciding if I should do similar so glad that you beta me to it.
In the last nine or so days there have been four mornings when MEL ('YMML') has experienced fog. The effects have been variable, from disastrous one day for the domestic airlines with two hour plus delays for some flights, and hour long ones or cancellations for others, to another morning when at least four international flights (carriers such as CZ GA and PR) that were arriving in MEL around 0630 hours having to divert to SYD. The other couple of days didn't seem to be nearly so bad.
As often the case, weather is highly localised. Fog hasn't seemed to be quite the problem where I live in Melbourne that it has been lately at the airport.
Many AFF members already 'fly the night before.' This can be wise, but it adds to the cost of a trip if using an hotel or other paid accommodation, and not everyone (especially those with children) can spare the time, or want to adopt this strategy.
Don't be surprised if from around the 0600 - 0700 hours mark there are extensive delays. If the fog continues to 1000, delays will rapidly compound. ATC will typically hold flights at an origin such as ADL or SYD. Crewing will get out of whack with cancellations inevitable, and some passengers unable to fly at all or promptly.
Unfortunately MEL has become so important (lagging SYD only by a smidgeon in overall passenger numbers, and probably ahead of it domestically as SYD has a greater percentage using international flights) that on such days, at least a third of most domestic airlines' fleets travel to and from MEL so if the aircraft has to visit during the morning, in a worst case it can be then late all day. This depends on whether the aircraft schedules have padding and also if some of the allowed turnarounds are generous.
My worst fog-related delay at MEL some years back saw a wait of seven hours until VA uplifted me. Lack of information did not impress some fellow travellers.
On such days one feels for airline operations staff as despite sophisticated software and years of experience, working in such a situation and trying to balance costs with getting us to where we're going must be stressful.
