Visibility conditions

The flight took place at night. There was a new moon, but this was unlikely to have given much light. It was winter time, with clouds extending to considerable height, possibly completely hiding the mountain peaks. The flight itself was authorized under “IFR” (Instrument Flight Rules) and the conditions appear to be “IMC” (Instrument Meteorological Conditions) which means there was little, if any, visibility out of the cockpit. We should not be misled by reports from ground stations apparently indicating good visibility. These provide accurate sightings at ground level, for example visibility 5 miles, scattered cloud at 4000 feet. But if a plane is flying in scattered cloud, the visibility is consistently less because it is flying in and out of cloud, and is adversely affected by the slant angle while looking through it. The only way to have good visibility is to fly above the cloud cover.

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