OK, we'll have to put this one in the "mystery question" compartment until it crops up again. Definitely strange.

Hi Rossy Bob And Richard


Just having a browse and spotted your question on alternates.I sat this exam last week,fortunately i passed with 88% but one of the questions i got wrong was this same question as you are discussing and it was how rossy described it:tempo sct cb thats all it gave,i selected no alternate required and got it wrong, my only thought was that when cb are forecast a alternate is required? Had me confused too.
Anyhow back to study,performance last subject.By the way Thanks Bob for A great website to access info and feedback,has made life easier knowing there is support when required.
Dave

Dave, thanks very much for posting. We'll have to look into this further.

Cheers,

Rich

There is no doubt that there is a difference between Cumulonimbus cloud, CB, and thunderstorms, TS. CB is a cloud type while TS is a weather event. It is true that you cannot have a thunderstorm unless you have a cumulonimbus cloud, however, you can certainly have a cumulonimbus cloud without a thunderstorm.

If a TAF contains CB in the cloud section but does not mention TS in the weather section there is no reason to apply any operational requirement [holding or alternate fuel] unless there is more than 4/8 of cloud below the alternate minimum ceiling. However the AIP says [ENR 1.1 57.2.5] that any mention of TS imposes the OPR no matter what the cloud amount and height may be.

If the exam was marking you wrong for saying that SCT CB would not impose an alternate requirement, then they have got it wrong. I have contacted a number of respected IFR test officers for their opinion and they all agree that CB alone, with no mention of TS, does not impose an alternate requirement.

I answered the same as dave i believe. My interpretation was that no operation requirement existed since there was no other info and the info that was supplied wasnt enought to impose any requirement Definitely no mention of TS and no mention of cloud height or anything. SCT CB only to the best of my knowledge.

Hey Rich, whilst im at it, i have a question regarding flight time limitations.
With regards to CAO 48 para 1.17. If a pilot sets out to do a tour of duty of say 12 hrs and then has a day off, then the following day (say 3rd day) completes another tour of duty of say 11.5 hrs then how long does the period of rest after this second extended tour of duty need to be before he can complete a tour of duty of the usual 11hrs?

Are the requirements for this just the same as those listed in para 1.7 so it would be plus the additional 2 hrs (coz of the .5hrs over 11) and thus become 11 or 12 hrs depending what hrs are embraced or what? Sorry if this sounds a bit confusing.

I understand the requirements associated with normal tour of duties and also tour of duties that aren't rostered in excess of 11 hrs but become longer due to some other factor like holding or diversions but i just cant be sure on what the requirements are after completing an extended (para 1.17) flight with regards to the necessary time of rest required before one could complete a normal 11 hr tour of duty again.

Thanks in advance

Providing you are VFR and below 5700kg, you may do a tour of duty of up to 15hr. You cannot do two consecutive such tours unless you have 24 hours rest between them. e.g. either side of your day off. As for the rest after the second extended tour of duty, there would be no penalty for exceeding the normal 11hr since these extended tours of duty are permitted for VFR below 5700kg. The next rest would simply be a 'normal' rest of 9hr including the hours of 10pm to 6am or 10hr.

Hi Bob
Did you end up getting resolution on the Air Law exam question that everyone was getting wrong where it says, is an Alternate required or 60 mins holding or both or neither if the forecast says TEMPO SCT CB? I have my AirLaw exam on Wednesday and after reading the posts am confused how to answer it if it comes up. Everyone else seems to have entered the correct answer but got it wrong.

Gidday benelong

I can't get a clear answer from CASA on that one. They keep giving me someone else to contact. I must admit that it is a bit of an academic argument, and in practice it would be advisable to treat CBs as always having thunderstorm weather associated with them. If you have previously answered that question and been marked incorrect, maybe it would be wise to answer that CBs automatically impose the OPR even if TS is not mentioned.

I can't for the life of me understand why the wording in AIP ENR 1.1 para 58.2.5 doesn't just say that. Anyway, good luck with the exam - please let us know how you go....

Bob
I posed the question to Bill Whitworth and three of his senior instructors and they all answered that you need an alternate or 60minutes hold. When I told Bill about the TS rule he scratched his head and pondered. All the instructors said that CB basically turns into TS and hence the requirement. They backed this up with AIP 1.1 88 "when TS or their associated severe turbulence or their probability is forecast...". this was good enough for them and they were all posed the question individually. I can see their point now.

Also you have a question repeated in your book a few times asking, In the last 6 days you have flown 23 hours. You are not restricted by the flight time limits of 30 or 365 consecutive days. Today you may fly for a maximum of 8hrs, 3hrs, 7hrs or 2hrs?
The answer you give is 7hrs. I know you can only fly for 30 hrs in a week but your question states (oddly) that you are NOT restricted by the 30 hour rule, hence you should be able to fly for the normal 8hrs in any day. What am I missing here, have I read the question wrong, is it something to do with a day off or what?
Thanks Martin