jamesnixon.com
Melbourne Fog.
23rd. April 2018 
Waking-up in a cloud
Melbourne sits at sea-level. Melbourne Airport is 434 feet above it. So if you wake up just under a cloud, they are in it at the airport. If you are going somewhere by plane, there will be delays. Here are fourteen things non-pilots need to know about Melbourne's two fog seasons, (Autumn and Spring) when high-pressure systems sit over the top
1. All planes can take-off in fog but not all can land in fog.
2. They need 150m visibility to take off and 800m to land.
3. To operate in conditions less than these, you need upgraded:
Airport equipment,
Aircraft,
Pilots, and
Procedures known as Low Vis Procedures or Operations (LVPs/ LVO’s).
4. LVPs slow the operation of the airport by 50%, no towing-of-planes around for engineering / storage, less vehicles driving around, and
5. Protected Areas Become Active: all metal things (ie planes) being kept back from the runway so as to protect the Glideslope and Localiser beams from being affected. All aircraft hold at red Cat 2 and Cat 3 points, further back from the runways, instead of Cat 1 (normal) holding points.
6. Cloud is disregarded as a limiting factor, visibility becomes controlling.
7. There is one level of takeoff visibility. 150m can be reduced to 125m. The runway lights have 15m spacing and the runway edge lights are spaced at 60m intervals.
8. There are three levels of landing visibility:
Cat 1 550 meters
Cat 2 350 meters
Cat 3a 200 meters (3 runway lights visible), and
Cat 3b 75 metres (1 runway light visible; but you may require more at the far end of the runway for taxing purposes).
9. Auto-landings are used for Cat 2 (recommended) and Cat 3 (mandatory).
10. Go-Arounds are performed unless everything is going well at the Decision Height (DH):
Cat 1 = 200 feet,
Cat 2 = 100 feet,
Cat 3a = 50 feet
Cat 3b = 0 feet (Yes, you can go around provided reverse thrust is not selected).
11. Cat 3b means that the aircraft is in perfect condition, if anything fails below 200 feet, Cat 3a will still be available, this is called Fail Operational (ie: something has failed but the whole system still works).
12. Fog thickens up at sunrise, lifting to become low cloud. As soon as the temperature and due point become the same, the fog vanishes.
13. To know if Melbourne Airport is using Lo Vis Procedures, check Twitter handle: @ymmlatis for the phrase:
“LOW VISIBILITY PROCEDURES IN FORCE.
HIGH INTENSITY APPROACH & HIGH INTENSITY
RWY LIGHTING OPERATING.”
14. For years Australia didn’t want to pay for upgraded Airports ( we still only have one runway at Melbourne, Sydney and Perth capable of Cat 3 ops); it was cheaper to suffer diversions six days a year ... so pilots could operate in fog all over the world except Australia, which is why I dubbed Australia:
“The Cleanest Third World
Country On The Planet."
Cheap airlines refuse to pay for pilots to be trained to the higher standard, and to keep them "current", which means giving them extra simulator sessions; so some airlines will get-in during times of fog and others will divert.
23rd. April 2018
_________________________________________________