Alternate / Holding requirement due to TS and associated turbulence

[JulieFlyGal]

Referring to AIP ENR 1.1, section 58.2.5 which reads;

"When thunderstorms or their associated severe turbulence or their probability is forecast at the destination, sufficient fuel must be carried to proceed to an alternate or hold for 1. 30 minutes INTER or 2. 60 minutes TEMPO' "

Simple question is, does simply having 'CB' on the TAF constitute having 'thunderstorms or their associated severe turbulence' at the destination?

Or is it only 'TS' in the TAF that triggers this requirement for an alternate or holding?

[Josh Cox]

The way I apply that is:

If the TS/CB is in the base forecast, i.e. not an inter or tempo, then alternate is required,

If the TS/CB is in the inter or tempo section of the TAF, then an inter or tempo is required.

[Arm out the window]

In GEN 3-5 12.12.6 it says 'whenever cumulonimbus is forecast, the degree of associated thunderstorm activity or probability of occurrence is included', so I think that probably answers your question.

If CBs are in the TAF then the probability of thunderstorms will also be there, and whether they're on the whole time or for INTER / TEMPO.

[itsnotthatbloodyhard]

In Australlia it's as AOTW says - I don't think I've ever seen CB forecast without an associated TS risk. Around Asia, though, it's not uncommon to see CB on a forecast without any mention of TS, and what dehg5776 says is correct - no requirement to carry extra fuel. I know what I'd be doing, though.;)

[esreverlluf]

CB only = no legal requirement, however the practicality would be . . .