What has happened to CAVOK

[renard]

Lots of ATIS reports in the UK no have

Visibilty 10km
No Cloud Detected

This seems pretty much the same as CAVOK.

Any reason why CAVOK isn’t used?

Could it be that the automatic weather systems can’t detect clouds at a distance from the airport?

[T250]

Been this way for a while.

'NCD' stands for no cloud detected, by the automated system. CAVOK can only be promulgated by a human observer should the criteria be met.

[renard]

Thanks for that, thought that might be the reason.

[cavuman1]

One wonders what became of Clear and Visibility Unlimited...

- cavuman1 a/k/a Ed

[FlightDetent]

CAVOK means no Clouds in the TMA below Transition Altitude or 5000 AAL ?

[chevvron]

CAVOK = vis + 10km, no CB, no other cloud below 5,000ft aal and no precipitation.
It's always the last bit people forget.
(Nothing to do with being in or under a TMA)

[chevvron]

One wonders what became of Clear and Visibility Unlimited...

- cavuman1 a/k/a Ed
I may be wrong but I believe CAVU is only used in the USA.

[Talkdownman]

I may be wrong but I believe CAVU is only used in the USA.
Well, C and V are not likely to be U in the UK, are they...

[vintage ATCO]

What ever happened to oktas . . . . . ?

[FlightDetent]

UK differences from ICAO Annex 3 (my PDF copy may not be the latest)

"The reporting of clouds in the METAR of operational significance will be introduced on 6 October 2005. From this date, the abbreviation NSC (no significant cloud) will be used if there are no clouds of operational significance, no TCU or CB; the abbreviations CAVOK and SKC are not appropriate."

[ZOOKER]

A few months back, my local airfield, 3NM to the west, was giving 'No Significant Cloud' on the ATIS. At this time, I sat, with a nice Chardonnay, watching the TS in the overhead. Down to cost at the end of the day. A great shame, as during the present period of inter-glacial climate change, we need the most accurate Wx obs we can get our hands on.

[chevvron]

What ever happened to oktas . . . . . ?
Superseded by :
FEW = 1 Okta
Scattered (SCT) = 2 to 4 oktas
Broken (BKN) = 5 to 7 oktas
Overcast (OVC) = 8 oktas.
FEW and SCT are 'cloud base' and BKN and OVC are 'cloud ceiling'.

But then you were joking weren't you.

[chevvron]

UK differences from ICAO Annex 3 (my PDF copy may not be the latest)

"The reporting of clouds in the METAR of operational significance will be introduced on 6 October 2005. From this date, the abbreviation NSC (no significant cloud) will be used if there are no clouds of operational significance, no TCU or CB; the abbreviations CAVOK and SKC are not appropriate."
NSC refers to no cloud below 5,000ft aal.

[Floppy Link]

chevvron, FEW is 1-2

[FlightDetent]

NSC refers to no cloud below 5,000ft aal. I seem to remember the same, however the class on that day had "New ICAO METAR standard 1998" listed on the schedule.

I did look up the CAVOK definition in Annex 3, and the 5000 limit is not there. No operational significance they say.

[Andy Mayes]

NSC refers to no cloud below 5,000ft aal.

AND no TCU or CB at any level.

[GWYN]

Ummmm..............Chevvron and Floppy Link, what I have never understood is that if FEW, SCT, BKN and OVC are defined in terms of OKTAS, why, oh why, did we ever have to get rid of OKTAS and introduce another level of complexity???

[Talkdownman]

if FEW, SCT, BKN and OVC are defined in terms of OKTAS, why, oh why, did we ever have to get rid of OKTAS and introduce another level of complexity???
Because, it seems, everything has to be complicated into fours, as are the CAP774 types of ATS: Basic, Traffic, Decon, and Procedural. Then everything will blur into one another and make life difficult.

Anyway, I'm surprised EASA hasn't decimalised it again, for it was 'tenths' before oktas...

[LookingForAJob]

types of ATS: Basic, Traffic, Decon, and Procedural.Sorry to be OT and a pedant, but I think you mean FIS. Although how a procedural control service can be called a FIS I’m not really sure. So it’s not four but three more correctly in my view. :bored:

[chevvron]

Ummmm..............Chevvron and Floppy Link, what I have never understood is that if FEW, SCT, BKN and OVC are defined in terms of OKTAS, why, oh why, did we ever have to get rid of OKTAS and introduce another level of complexity???
Maybe because the Americans have been doing it since the '60s?:rolleyes: