[CAN NOT REPRODUCE]The fog does not limit the visibility of airport lights

[Goggles]

OK, figured it out.

 

 

 

I loaded the latest beta version and the visibility mod works. At night, you cannot see the lights all the way to the end of the runway with reduced visibility, except below.

 

 

Bug fix has not been carried over to the regular 2.9.16.18 version. Only in the open beta version.

 

 

 

In the open beta version:

 

 

 

At night, you can still see lights beyond the set fog visibility:

 

 

Visibility set to 200m, lights appear to 350m

Visibility set to 300m, lights appear to 550m

Visibility set to 1200m, lights appear to 2400m: At Batumi, runway length is 2400m, so you can see to the end. Should only be able to see lights up to 1200m, half way down the runway.

 

 

 

Tweaking required, to reduce visibility of lights in fog at night by at least 40%.

 

 

 

At night, when fog is selected, if the cloud density is set to 9 or 10, there is no fog anymore, and the sky appears bright light blue, and horizon appears against shadow of blocked objects.

Edited June 21, 2020 by Goggles

[Goggles]

"At night, you can still see lights beyond the set fog visibility"

 

 

That means, if you want to shoot a CAT II (RVR 1200 feet = 360meters), you have to set the fog visibility to 185 meters, if you want a realistic night visual environment. The runway lights are about 50 metres apart, and with the fog visibility set to 185 meters, I can count 7 lights: 7 x 50 = 350 meters.

 

 

 

You also have to set the cloud height to 300 meters, thickness 2000 meters and density to 8. Fog thickness 1000 meters. Otherwise, the vis goes up.

[BIGNEWY]

It seems ok for me, fog behaving as it should as far as I can tell.

 

thanks

[Mars Exulte]

Why wouldn't you be able to see the lights? It's fog, not a brick wall. The whole purpose of the lights is to be visible in poor conditions.

[discwalker]

Why wouldn't you be able to see the lights? It's fog, not a brick wall. The whole purpose of the lights is to be visible in poor conditions.

 

https://en.wikipedia.org/wiki/Smolensk_air_disaster#Approach

The Yak-40 crew estimated visibility was 200 metres (660 ft), but told PLF 101,[10] "you might try...(to make an approach)."

 

In the attached mission Spawn at Maykop, visibility clearly more than 500m what is set, as time passing by fog became stronger.

fog_test_2020_Morning_500m_visibility.miz

[Goggles]

Why wouldn't you be able to see the lights? It's fog, not a brick wall. The whole purpose of the lights is to be visible in poor conditions.

 

The lights are key in having sufficient visibility in order to continue an approach and land. That's why most runways used for low visibility approaches have high intensity approach lights and high intensity runway centre line and edge lights. Without those, especially at night, you would not be allowed to continue the approach and land if the visibility was too low for visual flight rules.

 

That's why, in low conditions such as fog, visibility is measured using lights, since it's the lights that guide you into making a successful approach and landing, and not ground features that may appear.

 

To that end, instruments that measure runway visibility essentially determine how far the runway lights can be seen, and report that value as the Runway Visual Range visibility.

 

Before the advent of transmissometers, with the latest versions using lasers and forward scatter meters, Runway Visual Range (RVR) was eyeballed using runway lights:

 

"Originally RVR was measured by a person, either by viewing the runway lights from the top of a vehicle parked on the runway threshold, or by viewing special angled runway lights from a tower at one side of the runway. The number of lights visible could then be converted to a distance to give the RVR. This is known as the human observer method and can still be used as a fall-back."

 

(https://en.wikipedia.org/wiki/Runway_visual_range)

 

When it's pitch black and foggy (less than 1800 meters), it wouldn't make any sense to report other than how far the lights can be seen, as you can't normally see anything else to guide you, especially in foggy conditions.

 

In the real world, runway light intensity can be varied, and turning the lights up to maximum only marginally improves the visibility. However, the instrument that measures visibility, the transmissometer, is calibrated to take into account runway light intensity. But it still reports how far the lights can be seen.

 

If you ever get a night rating, you will learn to approach and land with the airplane's landing lights off, as it is the perspective of the runway lights that should guide you, rather than other ground features that may or may not appear.

 

 

Any pilot who is to conduct an instrument approach wants to know if there is sufficient visibility at minimums (200 feet AGL on a Cat I) in order to continue the approach and land, meaning: at decision height, are there enough runway lights ahead that will allow sufficient reference to safely manually land the airplane.

 

 

So, as far as DCS is concerned, when the 'Fog' feature is ticked, there is no basis for setting a visibility that doesn't correspond to how far the lights, including runway and approach lights can be seen.

[Goggles]

https://en.wikipedia.org/wiki/Smolensk_air_disaster#Approach

 

 

In the attached mission Spawn at Maykop, visibility clearly more than 500m what is set, as time passing by fog became stronger.

 

 

 

Visibilty 200 meters, clearly a Cat III operation, at an airport that was essentially non-precision. That's how far the Yak crew could see the lights. Should never have attempted the approach; any civilian doing that would have been canned.

[Goggles]

It seems ok for me, fog behaving as it should as far as I can tell.

 

thanks

 

Do you acknowledge that the change was not implemented in the latest stable version?

 

It works for me only in the open beta.