Go Back  PPRuNe Forums > Ground & Other Ops Forums > ATC Issues
Reload this Page >

What has happened to CAVOK

ATC Issues A place where pilots may enter the 'lions den' that is Air Traffic Control in complete safety and find out the answers to all those obscure topics which you always wanted to know the answer to but were afraid to ask.

What has happened to CAVOK

Old 30th Nov 2018, 10:04
  #1 (permalink)  
Thread Starter
 
Join Date: Apr 2001
Location: EGPH
Posts: 121
What has happened to CAVOK

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 isnít used?

Could it be that the automatic weather systems canít detect clouds at a distance from the airport?
renard is offline  
Old 30th Nov 2018, 10:20
  #2 (permalink)  
 
Join Date: Jun 2008
Location: Cheshire, UK
Posts: 326
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.
T250 is offline  
Old 30th Nov 2018, 10:38
  #3 (permalink)  
Thread Starter
 
Join Date: Apr 2001
Location: EGPH
Posts: 121
Thanks for that, thought that might be the reason.
renard is offline  
Old 30th Nov 2018, 14:44
  #4 (permalink)  
 
Join Date: Feb 2015
Location: Cincinnati, Ohio
Posts: 629
One wonders what became of Clear and Visibility Unlimited...

- cavuman1 a/k/a Ed
cavuman1 is offline  
Old 30th Nov 2018, 14:48
  #5 (permalink)  

Only half a speed-brake
 
Join Date: Apr 2003
Location: Commuting home
Age: 44
Posts: 3,507
CAVOK means no Clouds in the TMA below Transition Altitude or 5000 AAL ?
FlightDetent is offline  
Old 30th Nov 2018, 15:17
  #6 (permalink)  
 
Join Date: Nov 2005
Location: River Thames & Surrey
Age: 73
Posts: 9,181
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 is offline  
Old 30th Nov 2018, 15:18
  #7 (permalink)  
 
Join Date: Nov 2005
Location: River Thames & Surrey
Age: 73
Posts: 9,181
Originally Posted by cavuman1 View Post
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.
chevvron is offline  
Old 30th Nov 2018, 16:35
  #8 (permalink)  
 
Join Date: Jul 2004
Location: On the wireless...
Posts: 1,896
Originally Posted by chevvron View Post
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...
Talkdownman is offline  
Old 30th Nov 2018, 18:43
  #9 (permalink)  
aceatco, retired
 
Join Date: Sep 2002
Location: one airshow or another
Posts: 1,431
What ever happened to oktas . . . . . ?
vintage ATCO is offline  
Old 30th Nov 2018, 20:32
  #10 (permalink)  

Only half a speed-brake
 
Join Date: Apr 2003
Location: Commuting home
Age: 44
Posts: 3,507
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."
FlightDetent is offline  
Old 30th Nov 2018, 21:03
  #11 (permalink)  
 
Join Date: Jan 2008
Location: The foot of Mt. Belzoni.
Posts: 1,995
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.
ZOOKER is offline  
Old 1st Dec 2018, 04:27
  #12 (permalink)  
 
Join Date: Nov 2005
Location: River Thames & Surrey
Age: 73
Posts: 9,181
Originally Posted by vintage ATCO View Post
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 is offline  
Old 1st Dec 2018, 04:29
  #13 (permalink)  
 
Join Date: Nov 2005
Location: River Thames & Surrey
Age: 73
Posts: 9,181
Originally Posted by FlightDetent View Post
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.
chevvron is offline  
Old 1st Dec 2018, 15:01
  #14 (permalink)  
 
Join Date: Sep 1999
Location: EGPT/ESVS
Posts: 755
chevvron, FEW is 1-2
Floppy Link is offline  
Old 1st Dec 2018, 16:51
  #15 (permalink)  

Only half a speed-brake
 
Join Date: Apr 2003
Location: Commuting home
Age: 44
Posts: 3,507
Originally Posted by chevvron View Post
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.
FlightDetent is offline  
Old 1st Dec 2018, 20:07
  #16 (permalink)  
 
Join Date: Apr 2006
Location: South Coast and Suffolk
Posts: 150
Originally Posted by chevvron View Post
NSC refers to no cloud below 5,000ft aal.
AND no TCU or CB at any level.
Andy Mayes is offline  
Old 10th Dec 2018, 16:55
  #17 (permalink)  
 
Join Date: Jan 2000
Location: PommyLand - but I'll be back!
Posts: 180
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???
GWYN is offline  
Old 10th Dec 2018, 19:56
  #18 (permalink)  
 
Join Date: Jul 2004
Location: On the wireless...
Posts: 1,896
Originally Posted by GWYN View Post
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...
Talkdownman is offline  
Old 10th Dec 2018, 20:52
  #19 (permalink)  
 
Join Date: Jun 2001
Location: Wherever someone will pay me to do fun stuff
Posts: 1
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 Iím not really sure. So itís not four but three more correctly in my view.
LookingForAJob is offline  
Old 10th Dec 2018, 21:00
  #20 (permalink)  
 
Join Date: Nov 2005
Location: River Thames & Surrey
Age: 73
Posts: 9,181
Originally Posted by GWYN View Post
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?
chevvron is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.