I will divert if the wx drops below the limit and I don't have an alternate from the missed approach. I know it would be annoying but that is the intention of the rule in my opinion.
I do about 700 hours a year and have never had to do it in the last decade that I can recall so it's not a big imposition.
For you to be airborne without alternate fuel, and the wx dropping to the extent that an alternate is required on destination, something unusual has happened either with the forecasting, or your decision making at the pre-flight stage.
Sometimes due payload/ destination combinations it is on the cards to have to bug out at top of descent but it hasn't happened to me yet.
If you began your descent and threw away your opportunity to divert somewhere suitable and the wx ( which has already been incorrectly forecast) continues to deteriorate then I think you'd have a hard time explaining your decision not to divert.

Why?

You said the wx was incorrectly forecast!

In the scenario I painted ( poorly I know) , the pilot knows that the destination has deteriorated to the point that it requires an alternate. If the pilot has the option to divert at that point to a suitable airport, but chooses to reduce his/her options to just one airport, an airport that requires an alternate, and then an incident occurs due to the weather deteriorating further, how would you explain the decision? I might be wrong but I doubt you'd be able to convince many that your decision to fly out of range of a suitable airport was a good decision.

Captain Fathom, During the investigation of the Mildura incident the ATSB sought clarification from CASA about this.
CASA said "In addition, CASA clarified that there was no ‘strategic difference between an in-flight scenario and a pre-flight plan' in relation to the use of forecasts. "
And "for in-flight planning considerations the decision making must be based on the forecast element so a pilot must hold an alternate and applicable fuel but is able to make a decision to attempt an approach at the destination should the flight crew calculate additional fuel is available to do so. Specific operator procedures and fuel policies may also need to be considered. "
Thoughts?

Hindsight is a wonderful thing.
You can only make a decision on the information available at the time.
That information may or may not be accurate.
You can't spend your aviation career wondering how you will explain your desicions to the authorities. You'll never take off in that case!

Hindsight is not required in the scenario we're discussing. The pilot knows that wx is now below alternate requirements, the pilot knows that the wx forecasters are having a bad day, the pilot knows he/she still has the ability to divert. Simple.
To get in that scenario is very unusual in Airline flying. Both the big players in Australia require their jets to have enough gas to get to an airport that does not require an alternate
so it is planned for. I can't speak for other types of operation.

Eh? From the Mildura report:

Might've changed since then...

Cap'n Bloggs,
What you've posted above doesn't rule out what I said
Just because you can dispatch without an alternate doesn't mean you can be airborne and not have fuel to an airport that doesn't require an alternate.
I'll give a practical example;
If I am inbound to YMML in my 737 and planning to land with 2.5 T ( Just over an hour) and I get new YMML wx that say vis has dropped to 5km ( my company says I can't use Special alternate minima), I now have to look around to find an airfield that I can reach that doesn't require an alternate.....no problem YMAV will do, but if YMAV is also 5km Viz I have to keep searching, no worries, YSCB looks CAVOK. I am still legal as I can currently reach YSCB. No emergency exists. Now I need to calculate when I will lose my ability to divert to YSCB, let's say that on descent though 5000ft I will lose my ability to divert to YSCB. I now can't go past 5000ft without being in breach of both company manuals and CASA's understanding of the rules. If I get to 6000ft and YMML and YMAV still require an alternate I have to bug out to YSCB in order to 'always have fuel to a suitable airport '.
This all sounds very inconvenient on paper but in real life, if the wx is anywhere near the alternate requirements, you simply carry YSCB from the YMML runway when you choose your departure fuel. Easy.

And there in lies the stupidity of our whole situation.

You are at 6000ft, so 20nm give or take a bit from the airfield, you are flying the star and can see the runway.

The forecast i.e. the prediction of what the computer models reckon the weather will be like (because the BOM has removed humans with forecasting experience from the equation pretty much) says an alternate is required.

Do you bug out to canberra to “stay legal” or do you use your ability as an authorised met observer to say “i can see the runway and i can see the surrounding weather environment (no great wall of showers about to cross the runway or approach path for example) and i am going to go and land at my destination”

Fuel policies, CAR234 and met forecasting are a means of risk mitigation intended to obviate the need for some poor sod to plonk his/her aeroplane in the field/ocean/multilane highway because they didnt consider the weather.

There needs to be some measure of common sense (yeah I know, that isnt all that common) and use of the captains decision making perogative not blind adherance to rules even when they produce a less than optimal result.

If you go and fly a 747,380,777 or other such large people mover, the decision making becomes more challenging as the ability to find other airfields that can accommodate your aeroplane is reduced.

"or do you use your ability as an authorised met observer to say “i can see the runway and i can see the surrounding weather environment (no great wall of showers about to cross the runway or approach path for example) and i am going to go and land at my destination”

Is a pilot an Authorised met observer?

73Qanda, you gave the impression that QF and DJ aircraft carry an alternate. That is only the case when the weather at the destination requires an alternate. Otherwise, you arrive with your 2.5t and hope like hell when you're on final, the airport doesn't close.

That is exactly what happened at Mildura. Neither QF or DJ carried a true alternate, and both got caught out badly.

I am concerned that uneducated readers might think that "the big players in Australia" do carry alternates. They don't, as QF found out in their A330/CBR and A330/PER when the weather changed enroute a few years ago.

Snakecharma, I understand European rules require carriage of a "proper" alternate at all times ie fuel to get to your destination then to your alternate. Your problem then goes away.

I always thought so, as we pass on observed to other activities etc

At what point have you 'arrived' though? From where you can make the observed with confidence?

Yes, in some situations... AIP GEN 3.5, section 4.5.2. :ok:

Sorry Bloggs I didn't intend to give that impression.
Fair enough. For all the uneducated readers out there;
If you're on a Qantas or Virginia Australia jet, the company has instructed the Captain that he or she must ensure that at all times while airborne, there is sufficient fuel in the tanks to fly to an airport that has not dropped below the alternate weather requirements, or if it has, they have the fuel to hold until it is better again. This airport may be your destination and as such you won't necessarily have an alternate if the weather is mint.
Caveat, real life may get in the way in which case you are technically in an 'emergency' and the Captain will do whatever he or she thinks is best.

Does the company have to instruct this, or is it basic airmanship that you have fuel to land somewhere/anywhere?
When you takeoff, you have fuel to go somewhere!

Well yeah.
In as much as clearly defined at least.

73qanda,

It is difficult to understand some of the things you are saying.

At "all times"? Are you serious? Do these words ("at all times") appear in your ops manual or some CASA rule? Or is this just your interpretation?

If the forecast for your destination was good before you departed, and you didn't load any alternate/holding fuel and your destination is REMOTE, how on earth can you say that, for the latter part of the flight, you have fuel to go somewhere else? How is the "at all times" being met, in this case?

Yeah, easy - when talking about YMAV, YMML and YSCB. How about if you're going somewhere REMOTE? What do you do then?

But for how long will you remain "legal"? Soon after you set course for YSCB, you will cease being "legal" will you not?

And why do you use the word "legal"? Does your Ops Manual stipulate that you must have alternate/holding fuel on board even when the requirement for same was unforeseen prior to departure?

They appear in the Qantas Flight Administration Manual ( not my manual).
I think I'll just cut and paste a couple of paragraphs out of the Mildura report in an attempt to make my point clear. I doubt it actually will because some of the posts above quite clearly show a lack of understanding of some common definitions, but here goes.

All of the quotes below are cut and paste from the ATSB's Mildura report.

Qantas issues instructions to it's pilots through a manual that says;
Keep in mind that to be a 'Suitable Airport' weather has to be above alternate minima.
So that's QF.

Virgin instruct their pilots through a similar manual, their manual says
In practice that is the exact same policy as QF but expressed with different words.

The ATSB noted this;
And so did this;
And CASA scratched their heads for a while before saying that there was And For me, that is quite clear. If I am wrong I am always ready to learn and admit it so I look forward to someone explaining that you can ignore the alternate requirements while airborne, but at this stage I'll keep on putting on gas for the nearest suitable if destination is within cooee of the alternate minima.
PS, if you do have a crack at it, please explain why someone went to the trouble of inventing Special Alternate Minima for use airborne? What advantage would it give if alternate minima isn't used inflight?

73qanda
 

73Q, I don't think you're a High Capacity pilot or you'd know that you're quoting is what you'll find in every airlines Fuel Policy, and you're taking it out of context!
It doesn't imply you'll have fuel to another port if your destination suddenly requires an alternate due to un-forecast changes, however if you have fuel to another port at the time it deteriorates, your obliged to apply the altn requirement and divert, or if it goes sour you'll answer for it.

The inflight quote ensures you don't continue on to destination after departure if your fuel level reduces to the level below what your min arrival fuel is pre departure. If your burn is > than planned (stronger H/Ws) such you won't have that fuel, you need to divert. E.G. o/head your last suitable A/P you must have burn to dest, app fuel, 10% of both and your FR etc. Less than that and you cannot continue. At some point after you leave behind that last suitable and your destination wx goes below altn min you will obviously not have altn fuel. Or if your last suitable enroute goes to altn as well.

SLAM is based on specific requirements and is available pre and inflt.