How much fog is too much?
 

Had a thought whilst i was driving west on friday morning. When i went past Richmond at 6am i couldn't see past the perimeter fence the fog was so thick. Then when i went past Bathurst airport it was the same story, except 2hours later as well. With Richmond being considered as the second airport for Sydney, and clearly fog is going to be an issue, how much fog is too much before a plane is able/not able to land? Or when planes are diverted from Sydney to Melbourne how much fog has there been? And what measures/procedures do planes use when there is significanly decreased visability when taking off/landing?

Thanks in advance,

Gerard

It depends on the available ILS and approach/airfield lighting status. There are 3 categories; Cat I, Cat II and Cat III, and each category allows for a lower minimum.

I can't guarantee the accuracy of it, but Wiki has an entry on it. http://en.wikipedia.org/wiki/Instrum...ILS_categories

You can have as much fog (or any other visibility affecting phenomenon) as you like, Gerard, providing it doesn't reduce the visibility to below 800m (in Australia) for landing.

The fog at Richmond during the winter months would reduce vis to well below 800m.

Thanks for the help. Was just wondering because if for example Richmond did go ahead then there would be a huge number of diversions..no? And as for regional airports, lets go with bathurst, do carries such a REX factor in the fog during winter into their timetables...or just hope for a good morning and if its foggy then its just a normal delay on the departure/arrival?

Gerard, the visibility requirements could be reduced by putting a higher category of ILS in (this applies anywhere).

I can't quote you on REX, but I know Qantaslink does not factor fog into its winter schedules. It just accepts that there may be disruptions, which are addressed on the day of operations.

Is Sydney going to be Cat III anytime soon?

No.

1. There's no practical need for it because we don't get enough days/hours of CAT III conditions each year.
2. It's way too expensive to maintain for the very few days we'd need it.

There are no airports in Australia that are equipped with anything higher than Cat 1 ILS.

Mick

What extra equipment is required to upgrade a Cat I airport to Cat III and what extra maintenance is required?