Cloud base vs Cloud ceiling

[George Yogi]

Can anybody help me to understand , when exactly an aviator refer cloud base or cloud ceiling ? ( I understand the meaning between the two)
Why don't pilots talk about cloud base ? Always i hear cloud ceiling.

From METAR we get cloud ceiling and we can calculate cloud base from OAT and Dew point , but I have never seen Pilots worry about the cloud base.Minimum ceiling is mentioned in our Flying school SOP as a rule for allowing VFR ,IFR , X cntry Flights but a Cloud base would give more clear picture to the pilot right ? since it is calculated from MSL and we use QNH for Local flying. Am i missing some thing here ? All help and comments are appreciated

[unbeg2b]

Cloud base I think is layer of cloud greater than 4 oktas (ie bkn in metar) below 20000ft Amal

[chevvron]

Cloudbase is the lowest cloud over the airfield eg 'few' or 'sct'; cloud ceiling is the cloud cover over more than half the visible sky ie 'bkn' or 'ovc'.

[George Yogi]

Thank you chevvron and unbeg2b but my thought is : If a commercial pilot who always fly IFR , a cloud base would be better than a cloud ceiling right ? so that at the time of take off he can expect where the clouds to be found since QNH and Cloud base are from the same datum. ( For ceiling : definition says , its the height abv surface or water below 20000ft / 6000m where clouds can be found which is covering half the sky)

Question :

1) Does the cloud base refer to a single cloud hence it is not significantly used
among pilots ? compared to ceiling which is a group when it covers more than
half of the sky
2) Is airline pilots really interested in cloud base or ceiling as they always fly
IFR , even though they can look out.
3) Only VFR pilots and Flying schools worry about these since for VFR ceiling
checks are mandatory ?

I know i am confused and quiet irritating , pls forgive

[chevvron]

No because iap mimima always quote 'ceiling' not 'cloudbase'.

[Crazy Voyager]

Clouds are not given in altitude, they're height over aerodrome level.


The only time I'm aware of that cloud base is used is for determining when approach lights have to be displayed. Everything else (I think) uses cloud ceiling.

[+TSRA]

1) Does the cloud base refer to a single cloud hence it is not significantly used
among pilots ? compared to ceiling which is a group when it covers more than
half of the sky

Clouds, in a METAR have their bases defined as height above ground level. That's for all clouds regardless of opacity. A ceiling is defined as any cloud base obscuring more than a certain amount of the sky, either given as BKN or OVC. Therefore, a ceiling is simply the base of cloud for which BKN or OVC is given.

[2) Is airline pilots really interested in cloud base or ceiling as they always fly IFR , even though they can look out.

Even in the IFR world all landings (except those rare, CATIIIc auto lands) require visual reference to the ground in order to land. We are mostly concerned about the ceiling (cloud base for BKN and OVC) being low, but any cloud that obscures our vision below our minimum IFR altitude is also cause for concern.

3) Only VFR pilots and Flying schools worry about these since for VFR ceiling checks are mandatory?

Remember, VFR means you cannot into a cloud or near a cloud within a specified distance. Therefore, flight schools have to weigh the probability that you would break those rules during takeoff, cruise, or landing. There may also be minimum weather conditions for a school in order to obtain insurance which may be much more restrictive than your regulatory body requires. These may, or may not, change with your level of experience. It's the same in the IFR world (about concerning ourselves with the lowest ceiling) but our minimums are much lower.

Hope that helps!

[George Yogi]

Thank you

+TSRA
Crazy Voyager
chevvron

For your Inputs.Will revert back for any further issues.