I have seen some ILS CAT III landings on YouTube and they are hair rising.
As a VFR pilot I cannot imagine the excitement and anticipation a pilot must be going through when conducting one of these landings.
Can you explain when a decision to attempt a CAT III landing versus a diversion to an alternate? (assuming both aerodrome and aircraft are sufficiently equipped)
When would you conduct a CAT IIIA & IIIB auto land?
When a pilot is properly trained and certified to conduct automatic landing in bad weather conditions, he has to abide by certain rules.
Auto Landings are classified into the following based on the limitations on visibility and cloud base.
Cloud Base (Decision Height)
20 (Boeing) or 23 (Airbus)
If you are an instrument-rated pilot without auto landing qualifications, you can only land in a Category I airfield that has a visibility of 800 meters (550 RVR) and a cloud base of 200 feet. Thereafter, you must disconnect the autopilot and land visually because you are not qualified to do an auto land.
When you are properly trained, you would be qualified for auto landing classified as Category II and can legally conduct an auto landing. However, you are restricted to a minimum visibility of 350 meters (300 meters in the US) and a cloud base of 100 feet.
With more experience, you are then re-certified to a Category IIIB qualification permitting you to land not only in Cat IIIA condition but also in Cat IIIB with a cloud base of 20 feet and a visibility of 100 meters.
I believe Category IIIC airfield are no longer maintained by any commercial airports around the world today due to the very high cost of maintaining such a facility although pilots and planes are capable of performing them.
If you are a VFR (visual flight rules) pilot, (being non-instrument rated), you are forbidden to attempt any auto landings.
If you are trained and qualified to conduct auto landing, and based on your qualification (Category II or IIIB) you would made your decision according to the limitations on the tables above.
For instance, if the weather reported at London Heathrow airport tells you that the visibility is 100 meters and a cloud base of 20 feet and you are flying a Boeing 777, you can legally land. If the visibility drops to 50 meters (above 1000 feet), you must divert to your alternate airport. So the decision making is quite simple if you understand the rules.
The moral of the story – if you are well trained and qualified, auto landing is the way to go. The excitement and anticipation is not what you think.
In fact, I used to feel more confident when I have to do an auto landing in bad weather as it reduces my stresses of having to make a diversion!
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