We have shown this magnificent video before of a landing in thick fog using autoland taken from the cockpit of a Boeing 757 by Hjörleifur Jóhannesson.
Many readers have asked us to put it back up on the news feed so here we go.
The Category 3A approach is to Oslo Gardemoen Airport. The wind is calm with visibility of just 225 meters on the runway.
Autoland systems were developed to enable aircraft to land virtually blind although they can be used in all levels of visibility.
However there are limits to the amount of wind component that an autoland system can handle.
For instance for a 747-400 the maximum headwind is 25 kts (28mph / 46km/hr), maximum tailwind 10 kts and a maximum crosswind of 25 kts.
However for the autoland to work an airport must be equipped with an appropriate Instrument Landing System (ILS) or Microwave Landing System (MLS).
There are various levels of ILS capability.
CAT 1 has a decision height for the pilot of 200ft (61m) and the pilot must be able to see 2400ft (55m) down the runway. For CAT 11 the decision height is 100ft (30m) and a runway visual range of 1000ft (300m). CAT111a 100ft and 660ft, CAT111b 50ft and 246ft.
Most airports have only a CAT 1 capability.
The first aircraft to be certified to CAT III standards was a Sud Aviation Caravelle in December 1968 followed by the Hawker-Siddeley Trident in May 1972 to CAT IIIa. It achieved CAT IIIb in 1975.
The Trident had been certified to CAT II in February 1968.
In the video listen for the heights being called out by the aircarft's systems. The 757 enters the fog at 500ft and the first lights of the runway are seeen at just 100ft above the runway.
Music on the video is by Paul Schwartz, Cantilena from the Aria 2: New Horizon album. For more videos by Hjörleifur Jóhannesson see: http://www.youtube.com/user/hjorleifur1961/videos
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