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Cloud Amount

  • linc90
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linc90 created the topic: Cloud Amount

Hey Rich Bob sorry for all the questions
I just did one of the online practice exams on alternates if the questions says

TAF YCCY 121930UTC 1220/1308 2101KT 6000 RA SCT010 FEW008
FM130400 9999 RA FEW015 SCT050
if my arrival is at 0410 what holding fuel do I require ?

I know we need 20min holding fuel because of the 30min after FM time from bad to good weather

Just wondering how it got bad weather ? is it because of the cloud SCT010 FEW008 accumulates to BKN(AIP ENR 1.1-86 para 58.2.1 note ) if so for alternate minimum sake do you say the cloud is at BKN008 because FEW008 this is the lowest cloud and the cumulative of the both if that makes sense ?

Thanks again Linc
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bobtait replied the topic: Cloud Amount

If both cloud layers are below the alternate minimum you must consider both. Note the AIP ENR 1.1 para 58.2.1 does not say the TAF has to mention BKN below the alternate minimum. It simply says you need an alternate if there is 'more than SCT' below the alternate minimum.

Bob
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  • jamup1977

jamup1977 replied the topic: Cloud Amount

On the same question FM 310400 I thought its 30 minutes before and 30 minutes after

so dont we have to calculate holding fuel from 0330 to ETA 0410?
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bobtait replied the topic: Cloud Amount

For a FM, when the weather is forecast to change from BAD to GOOD the 30 minutes is applied after the stated time (04) and the OPR will apply until 0430
For a FM, when the weather is forecast to change from GOOD TO BAD the 30 minutes is applied before the stated time (04) and the OPR will apply from 0330.

In this case, the weather is changing from BAD to GOOD, so the OPR applies until 4030. So since you arrival is at 0410, you can carry holding until 0430 because that's when the OPR will be lifted. See AIP ENR 1.1 para 59.2.3
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  • jamup1977

jamup1977 replied the topic: Cloud Amount

Thanks BOB.

Can you explain this on page 197 Question 9.

NON Pre Apr Aerodrome alternate minima is the ,

LAST +500 AND vis not less than 8 KM but answer for this C ( LAST +500 OR 8 KM)

Example on page 147 done on LAST +500 AND 8 K vis

Difference ??
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bobtait replied the topic: Cloud Amount

It depends on the wording in the question.

A question that's asking for the conditions that constitute the 'alternate minima' is asking for the items that must be considered when you are planning an alternate. You must CONSIDER both the cloud base AND the visibility.

However if a question asks what conditions would IMPOSE the requirement for an alternate. then EITHER the cloud OR the visibility could impose that requirement.
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