What BOM TAF's don't tell you.
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Blip
I live and work overseas mate so I don't need the lecture about what you do and don't get weather wise when overseas.
In Hong Kong it is COMMON and a daily event in Summer that TS are all around the Hong Kong Airport and it is NOT mentioned in the TAF. So my "silly" point is not so silly after all.
Your point was related to Brissy (where I was raised) so that's why I mentioned the ARFOR. You CAN get them in Australia last time I checked.
Gliderboy
ps At the end of the day use all available aids; common sense, experience and local knowledge (if available). Oh and those things on the wings are fuel tanks not airtanks
pps mate you like the quote button don't you
I live and work overseas mate so I don't need the lecture about what you do and don't get weather wise when overseas.
In Hong Kong it is COMMON and a daily event in Summer that TS are all around the Hong Kong Airport and it is NOT mentioned in the TAF. So my "silly" point is not so silly after all.
Your point was related to Brissy (where I was raised) so that's why I mentioned the ARFOR. You CAN get them in Australia last time I checked.
Gliderboy
ps At the end of the day use all available aids; common sense, experience and local knowledge (if available). Oh and those things on the wings are fuel tanks not airtanks
pps mate you like the quote button don't you
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Sorry to diverge the thread again.
One thing on the ARFOR over here in the west (not too sure bout you guys over the other side) that they have started doing that is annoying is replacing place names with thir designator.
This has been going on for roughly 6 months, I feel it is a loss of situational awareness and they always seem to pick places with a funny designator that you have no idea where it is! My PCA is getting a seriously abnormal workout!
The funny thing is other fields on the forcast, like Turbulence and to some extent the cloud it is being written out longhand.
Nil Sig now is Nil Significant
CUF now is Cumloform cloud etc.
At least with the places put the name like '' showers west of Perth(YPPH) after 06z'' for example
One thing on the ARFOR over here in the west (not too sure bout you guys over the other side) that they have started doing that is annoying is replacing place names with thir designator.
This has been going on for roughly 6 months, I feel it is a loss of situational awareness and they always seem to pick places with a funny designator that you have no idea where it is! My PCA is getting a seriously abnormal workout!
The funny thing is other fields on the forcast, like Turbulence and to some extent the cloud it is being written out longhand.
Nil Sig now is Nil Significant
CUF now is Cumloform cloud etc.
At least with the places put the name like '' showers west of Perth(YPPH) after 06z'' for example
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Call me old fashioned...
The cover your @rse component does apply in some instances. Met has been known to advertise possible severe hail on the general forecast after several million dollars worth car damage that wasn't forecast.
Met doesn't ever put 30 or 60 minutes holding fuel on. They just forecast the conditions. Since the demise of OPS in the CAA days the only person responsible for fuel is the pilot in command. As for TAFs, they are regulary amended and to assume that they'll only be amended on the 6 hourly schedule is ridiculous. We deal with amended TAFs all day every day. Major locations also receive a TTF service updated half hourly valid for 3 hours.
Obviously people will get caught out but then as already advertised there's a fair bit of PROBability involved.
Met doesn't ever put 30 or 60 minutes holding fuel on. They just forecast the conditions. Since the demise of OPS in the CAA days the only person responsible for fuel is the pilot in command. As for TAFs, they are regulary amended and to assume that they'll only be amended on the 6 hourly schedule is ridiculous. We deal with amended TAFs all day every day. Major locations also receive a TTF service updated half hourly valid for 3 hours.
Obviously people will get caught out but then as already advertised there's a fair bit of PROBability involved.
Thread Starter
I'm sorry SM4 Pirate but with respect, some of the things you said really don't make sense at all and indicate that you continue to miss the points I am making.
Firstly you said:
So you consider a 20% chance of something happening as really a zero chance do you?
I'm sure the meteorologists don't consider their probability estimates to be made "willy nilly".
I don't care how many times a PROB10, PROB20, PROB30, or PROB40 appears on a TAF. And why should anyone else care? If it is the honest estimate of the meteorologist, so be it.
No. Of course not. You are missing the point again. I am not suggesting that the flight crew will not receive weather updates along the way. Of course they will. But once they depart, they are stuck with the fuel they have in the tanks. For a commercial operation such as a major airline, there is often the commercial pressure to carry the least amount of fuel, especially if that fuel will offload revenue freight or pax.
Now if the crew at flight planning see 10PROB INTER TS, they can at least determine weather or not they will carry 30 mins holding fuel or not. They may decide to negotiate with the weight and balance people as to what can be left behind for the next flight (that does not have to deal with the PROB10 INTER TS or simply has a better load capacity such as a B767 vs B737) and what must be carried on that particular flight. The INFORMED decision can be made as to the cost of carrying holding fuel or diversion fuel verses not carrying the fuel and risking a PROB10, or PROB20.
If a PROB10 or PROB20 is increased in an TAF AMD to PROB30, PROB40, or PROB 50 (which is simply included in the TAF without the "PROB50") then that would come as no surprise to anyone. Those that are forced to divert due insufficient fuel would have taken the INFORMED risk of not carrying the fuel and lost. But if the PROB10 or PROB20 is not included, well then it does come down to "experience" or more likely luck.
CFPlnr's post includes exactly the kind of information I am talking about.
I honestly don't understand why anyone would argue against including this information in a TAF.
Gliderboy also said:
Just trying to keep the conversation legible. 
Firstly you said:
What if the chances don't increase?
then there will be no TS...
then there will be no TS...
If you willy nilly post every % say 10 and above on a TAF then for the 8 times a year a TS hits an aerodrome, it's forecast 250 times...
I don't care how many times a PROB10, PROB20, PROB30, or PROB40 appears on a TAF. And why should anyone else care? If it is the honest estimate of the meteorologist, so be it.
It's called hazard alerting, if you are within 1 hours flight time as an IFR you gt tld about the amended conditions, if VFR it will be braodcasy on area freq's; and flightwatch have all the info available at the click of a mouse; call them.
Are you suggesting a flight departing WSSS will have the latest on BN on departure and take that as the only time the WX is checked?
Are you suggesting a flight departing WSSS will have the latest on BN on departure and take that as the only time the WX is checked?
Now if the crew at flight planning see 10PROB INTER TS, they can at least determine weather or not they will carry 30 mins holding fuel or not. They may decide to negotiate with the weight and balance people as to what can be left behind for the next flight (that does not have to deal with the PROB10 INTER TS or simply has a better load capacity such as a B767 vs B737) and what must be carried on that particular flight. The INFORMED decision can be made as to the cost of carrying holding fuel or diversion fuel verses not carrying the fuel and risking a PROB10, or PROB20.
If a PROB10 or PROB20 is increased in an TAF AMD to PROB30, PROB40, or PROB 50 (which is simply included in the TAF without the "PROB50") then that would come as no surprise to anyone. Those that are forced to divert due insufficient fuel would have taken the INFORMED risk of not carrying the fuel and lost. But if the PROB10 or PROB20 is not included, well then it does come down to "experience" or more likely luck.
CFPlnr's post includes exactly the kind of information I am talking about.
10% chance of thunderstorm activity within 5nm of the airport 14/22Z.
Gliderboy also said:
pps mate you like the quote button don't you
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Blip, I don't want to get into a raging debate; a 20% chance is a 20% chance, not 100%... If it remains a 20% chance then it will not happen (it's reviewed constantly)... The forecast in a TAF is a living event; if the chance goes up; ie it becomes more likely that a storm will actually hit within the 5NM of the aerodrome reference point then the chance goes up and the TAF is amended to include the prob/inter period; mentioning a PROB 30% has the same effect as saying 100% possibility; but a 20% chance has the same effect as saying 0%; you have to draw the line somewhere; I believe it is in the right place.
You will never see a TS hit an aerodrome that is not forecast in a TAF; fact. It might be forecast only moments before, but it will happen.
I do see what you are saying; I just disagree with your point. I see no value in having a 10% chance being considered for fuel/alternate planning; that is 90% chance of not happening; the industry standards currently revolve around 30%; it seems to work, so what is the problem exactly? You seem to believe that we should be considering the chance, but why stop at 10% under your logic, why not 2%?
Having done some met stuff in my time; it's a science, not a science... It's a guess more often than not, educated yes, but still a guess; the change of a 20% chance, to a 30% chance maybe be just nothing more than a gut feeling of an individual based on previous experience, computer modelling be damned.
I guess my final point is, is it broken? if not, then don't mess with it.
You will never see a TS hit an aerodrome that is not forecast in a TAF; fact. It might be forecast only moments before, but it will happen.
I do see what you are saying; I just disagree with your point. I see no value in having a 10% chance being considered for fuel/alternate planning; that is 90% chance of not happening; the industry standards currently revolve around 30%; it seems to work, so what is the problem exactly? You seem to believe that we should be considering the chance, but why stop at 10% under your logic, why not 2%?
Having done some met stuff in my time; it's a science, not a science... It's a guess more often than not, educated yes, but still a guess; the change of a 20% chance, to a 30% chance maybe be just nothing more than a gut feeling of an individual based on previous experience, computer modelling be damned.
I guess my final point is, is it broken? if not, then don't mess with it.
You will never see a TS hit an aerodrome that is not forecast in a TAF; fact. It might be forecast only moments before, but it will happen.
I'm sorry but I have seen a TS hit SYD that was unforecast. Watched a huge line of CBs out out the window and on Wx radar as we flew into SYD. Nothing on the TAF or TTF. Acft dodging left right and centre as they arrived and departed SYD. Nothing on the TAF or TTF. Safely parked at the terminal when the TS hit. Lighnting strikes, heavy rain, black as midnight at 4 in the afternoon. Airport closed to all activities. Nothing on the TAF or TTF. The first forecast to mention TS was a TTF SPECI issued seven minutes after the storm hit the airfield.
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Bleve, ok yes one slipped through the net (and there are probably more examples too)... Perhaps there was a difference in forecast issued and forecast published... The point is it did get changed when the probability went over 30%; even in the case you mention, although it was late...
That experience and your comments highlight to me a fundamental problem with modern Australian aviation forecasts - and that problem is the over reliance on computer modelling. On the day in question it was obvious (for at least an hour beforehand) to anybody that bothered to look out the window or at a weather radar that SYD was going to be affected by TS. ie the human assesment was that the probabilty of TS was close to 100%. Yet nothing on any forecast. I suspect that the BOM was blindly issuing the computer model generated forecasts and the models had the prob at less than 30%. But the models were simply wrong and there was no human input into the accuracy of the forecast, ie using the Mark I eyeball to have a look out the window. I also suspect that ATC at SYD rang up the BOM after the airfield was closed and asked why the TTFs didn't have TS on them and then there was a mad scramble to catch up with reality.
Not too long ago TTFs were issued by real forecasters that used a blend of modelling and local knowledge and experience. That's what is missing these days - the human input. And that's why QF are paying for BOM forecasters to keep an eye on things and if the computer modelled forecasts aren't up to scratch it imposes it's own operational requirements in the form of OPRISK notices to it's crews.
Not too long ago TTFs were issued by real forecasters that used a blend of modelling and local knowledge and experience. That's what is missing these days - the human input. And that's why QF are paying for BOM forecasters to keep an eye on things and if the computer modelled forecasts aren't up to scratch it imposes it's own operational requirements in the form of OPRISK notices to it's crews.
Last edited by Bleve; 17th Jan 2007 at 04:47.
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You guys who fly all the time must see lots of this, cause I only fly 200 hr a year (mostly IFR) and I see enough examples of poor forcasts to make me very wary, but I generally have the luxury of carrying full fuel.
1) Before Xmas I dodged a big Cu/gestating CB north of YBOK that went on to belt the crap out of the Sunshine Coast. No mention of the possibility of CBs on any forcast!
2) Similar thing with a line of CBs between Alice and Ayers Rock middle of last year.
3) My personal favourite - having to fly an intrument appr into an aerodrome that has a CAVOK forcast!
R
1) Before Xmas I dodged a big Cu/gestating CB north of YBOK that went on to belt the crap out of the Sunshine Coast. No mention of the possibility of CBs on any forcast!
2) Similar thing with a line of CBs between Alice and Ayers Rock middle of last year.
3) My personal favourite - having to fly an intrument appr into an aerodrome that has a CAVOK forcast!
R
