Tafs and flying today
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Tafs and flying today
BRIZE NORTON EGVN 081021Z 081212 31013KT 9999 SCT040 PROB30 TEMPO 1218 32015G25KT 5000 SHRA
CRANFIELD EGTC 081200Z 081317 30014KT 9999 SCT040 TEMPO 1317 30017G27KT 7000 SHRA BKN030CB PROB40 TEMPO 1317 4000 +SHRA TSRAGS
BENSON EGUB 081023Z 081217 30012KT 9999 SCT040 PROB40 TEMPO 1217 30015G25KT 5000 SHRA
COVENTRY EGBE 081200Z 081322 31015G28KT 9999 SCT035 TEMPO 1318 7000 SHRA SCT030CB PROB30 TEMPO 1317 4000 TSRA SHGS BECMG 1821 30010KT
Hi,
I was planning to fly a triangular route today from Denham via Brize and Coventry, coming back past Cranfield. I looked at the above tafs and decided against it. I am now sat at home staring at a gorgeous blue sky! The flight would have been this aftenoon.
Was I being over cautious? Its just that these prob30 TSRA SH etc never seem to actually happen which is so frustrating!
What do you all think?
SS
CRANFIELD EGTC 081200Z 081317 30014KT 9999 SCT040 TEMPO 1317 30017G27KT 7000 SHRA BKN030CB PROB40 TEMPO 1317 4000 +SHRA TSRAGS
BENSON EGUB 081023Z 081217 30012KT 9999 SCT040 PROB40 TEMPO 1217 30015G25KT 5000 SHRA
COVENTRY EGBE 081200Z 081322 31015G28KT 9999 SCT035 TEMPO 1318 7000 SHRA SCT030CB PROB30 TEMPO 1317 4000 TSRA SHGS BECMG 1821 30010KT
Hi,
I was planning to fly a triangular route today from Denham via Brize and Coventry, coming back past Cranfield. I looked at the above tafs and decided against it. I am now sat at home staring at a gorgeous blue sky! The flight would have been this aftenoon.
Was I being over cautious? Its just that these prob30 TSRA SH etc never seem to actually happen which is so frustrating!
What do you all think?
SS
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TAFs looked similar last weekend: wasn't going to go, changed my mind in the end and there was not a thundercloud or even the briefest shower in sight. Sometimes it just seems there's no way of knowing in this kind of wx, doesn't it?
What is totally predictable is when you've run out of cash... I'm here with you on the ground, Skyseeker.
There will be other days...
What is totally predictable is when you've run out of cash... I'm here with you on the ground, Skyseeker.
There will be other days...
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Skyseeker
No you made exactly the right choice! OK, if you play the probability odds then you could have gone and been 70% OK!!? However, if the 30% probability did happen then you could have been in serious trouble.
I am afraid its one of the frustrations of the UK isn't it and this particular type of weather.
As they say, better to be on the ground wishing you had gone, than having gone and wishing your were on the ground!
Don't let any one persuade you to start taking chances with this type of TAF
Well done!
No you made exactly the right choice! OK, if you play the probability odds then you could have gone and been 70% OK!!? However, if the 30% probability did happen then you could have been in serious trouble.
I am afraid its one of the frustrations of the UK isn't it and this particular type of weather.
As they say, better to be on the ground wishing you had gone, than having gone and wishing your were on the ground!
Don't let any one persuade you to start taking chances with this type of TAF
Well done!
20 mins ago it was bright blue skies here, now it's dark and grey with hail and probably all kinds of nasty stuff you can't see.
If in doubt, there's no doubt.
Being scared in the air is no fun.
If in doubt, there's no doubt.
Being scared in the air is no fun.
Join Date: May 2003
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Have been happily ensconsed in the pub most of the day, watching it switch from blue skies to +TSRA and back again.
Fierce squalls with it too.
As its NW, its cross at my strip and not a day to even think about opening the hangar doors.
Always go with caution and you will never be up there wishing....
Fierce squalls with it too.
As its NW, its cross at my strip and not a day to even think about opening the hangar doors.
Always go with caution and you will never be up there wishing....
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Its been pretty nasty here in the Midlands as well. Spells of nice sunshine then loads of gusty squalls and hailstorms etc. I was going to go for a quick flight between showers but decided against it.
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A wise man said, "You fly where the weather lets you fly."
So if your plan was to fly exactly that route no matter what, then you did the right thing not to go.
However, if you are prepared that at any time circumstances(weather) may impede your progress, and you are prepared to circumnavigate Cbs or hold off while a shower clears the field, then you missed a lovely day flying. I wasn't at the airfield looking at the sky so I've no idea what it was really like.
It's your shout.
Just as an aside, PROB(30-40) TEMPO are disregarded in airline terms.
So if your plan was to fly exactly that route no matter what, then you did the right thing not to go.
However, if you are prepared that at any time circumstances(weather) may impede your progress, and you are prepared to circumnavigate Cbs or hold off while a shower clears the field, then you missed a lovely day flying. I wasn't at the airfield looking at the sky so I've no idea what it was really like.
It's your shout.
Just as an aside, PROB(30-40) TEMPO are disregarded in airline terms.
niknak
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SS
Good thing you didn't go, because you would have met exactly what the tafs said, but then again, I do have the advantage of up to date technology which permits me to say "I told you so"
Miserlou
Please appraise us all of which airlines "disregard prob 30/40% on tafs", I've yet to come across any that do - it's an incredible risk to take.
Good thing you didn't go, because you would have met exactly what the tafs said, but then again, I do have the advantage of up to date technology which permits me to say "I told you so"
Miserlou
Please appraise us all of which airlines "disregard prob 30/40% on tafs", I've yet to come across any that do - it's an incredible risk to take.
Last edited by niknak; 8th May 2005 at 19:54.
Convective weather is, by its very nature, localised. Provided you make sure that you leave yourself an out, you can circumnavigate showers. But you do have to be prepared to modify your route and/or hold while showers pass.
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IMHO, Skyseeker is making the classic mistake of reading the TAFs to the exclusion of other sources of weather data. It's a mistake I used to make too.
Two things are important to know about TAFs:[list=1][*]They're not really aimed at VFR pilots. Why else do you think they fail to report visibilities above 10km, and are only available at airfields that have instrument approach procedures?
[*]They give a forecast for the immediate vicinity of the airfield.[/list=1]
The second point often leads people to misinterpret things like "PROB30 TEMPO 1316 SCT020CB". What this actually means is that there's a 30% chance of a CB going directly overhead the airfield (or very, very close). It certainly doesn't mean that there's a 30% chance of the whole sky being covered by scattered CB's over a wide area. Also, "SCT" means 3 to 4 oktas of cloud cover, which can easily be provided by a single CB. A TAF gives you a view "through the microscope" of what's going to happen in the 2.5 mile radius around the airfield - useful to have, but it badly needs to be put into context.
This is why you should look at Metform 215, which is the best form of weather data aimed at VFR pilots. This will give you two very important pieces of information that do not appear on the TAF/METAR:
When you see a PROB30 (or 40) for CB's, you should expect that there definitely will be CB's around, but they'll be well separated.
So, just because you saw blue skies all day doesn't mean the TAF was wrong. If you'd been up in the air, you'd have seen that the 215 gave a very accurate picture of "isolated" CB's.
Two things are important to know about TAFs:[list=1][*]They're not really aimed at VFR pilots. Why else do you think they fail to report visibilities above 10km, and are only available at airfields that have instrument approach procedures?
[*]They give a forecast for the immediate vicinity of the airfield.[/list=1]
The second point often leads people to misinterpret things like "PROB30 TEMPO 1316 SCT020CB". What this actually means is that there's a 30% chance of a CB going directly overhead the airfield (or very, very close). It certainly doesn't mean that there's a 30% chance of the whole sky being covered by scattered CB's over a wide area. Also, "SCT" means 3 to 4 oktas of cloud cover, which can easily be provided by a single CB. A TAF gives you a view "through the microscope" of what's going to happen in the 2.5 mile radius around the airfield - useful to have, but it badly needs to be put into context.
This is why you should look at Metform 215, which is the best form of weather data aimed at VFR pilots. This will give you two very important pieces of information that do not appear on the TAF/METAR:
- Visibilities above 10km. It makes a big difference if you know the vis is going to be 30km - you'll be able to spot those CB's from miles away and will have plenty of time to think about your route to avoid them.
- The Metform will usually say "ISOL" (isolated) when the TAF says "PROB30" where CB's are concerned. IMHO, "isolated" is a much more descriptive way of thinking about what's really going on.
When you see a PROB30 (or 40) for CB's, you should expect that there definitely will be CB's around, but they'll be well separated.
So, just because you saw blue skies all day doesn't mean the TAF was wrong. If you'd been up in the air, you'd have seen that the 215 gave a very accurate picture of "isolated" CB's.
Last edited by dmjw01; 8th May 2005 at 19:46.
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Formally, a number of airline's ops manuals allow crews to disregard PROB30 forecasts for a fuel decision. For example PROB30 TEMPO 1217 +TSRA could theoretically be ignored in terms of taking extra holding fuel.
In practice, any sensible crew would work out that PROB30 really means 1 time in 3 the met man will get it right so it's probably worth sticking a bit extra on.
In Private Flying terms, 1 time in 3 you'll find one of these looming over your turning point or destination so either don't fly or be prepared to vary your route or hold-off. Also remember these are very localised forecasts. Flexibility is the key to air power, someone once told me.....
In practice, any sensible crew would work out that PROB30 really means 1 time in 3 the met man will get it right so it's probably worth sticking a bit extra on.
In Private Flying terms, 1 time in 3 you'll find one of these looming over your turning point or destination so either don't fly or be prepared to vary your route or hold-off. Also remember these are very localised forecasts. Flexibility is the key to air power, someone once told me.....
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PROB30 really means 1 time in 3 the met man will get it right
I say again: the TAF is a forecast for the immediate vicinity of the airfield. What the PROB30 is really saying is there's a 30% chance of one of the isolated CB's happening to drift directly through the airfield's ATZ. The precise position and motion of individual CB's is something that weather forecasting simply can't predict with any certainty.
1 time in 3 you'll find one of these looming over your turning point or destination
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Skyseeker
Having read all these comments, remember that we do this for fun - we are not paid to fly and we don't have schedules to meet and we pay handsomely to ENJOY IT!
What other people do is up to them - but I am with you! There are plenty more good days for pleassure flying which are more enjoyable than dodging CBs, hail, winds etc and worrying what you are going to come across.
Having read all these comments, remember that we do this for fun - we are not paid to fly and we don't have schedules to meet and we pay handsomely to ENJOY IT!
What other people do is up to them - but I am with you! There are plenty more good days for pleassure flying which are more enjoyable than dodging CBs, hail, winds etc and worrying what you are going to come across.
niknak
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I think some may be getting or sending the wrong message.
Surely the message is, even if you're the most experienced aviator in the world, if the taf says "prob 30 or 40", there's a very high chance that CBs may be encountered anywhere in the vicintity, not just at the airfield.
Anyone who has had the misfortune to experience it will know that a CB can manifest themselves and out - run most types of G/A aircraft, and will almost certaintly bite you if you are stupid or unfortunate enough to fly in the vicinity of, or, God forbid, inside one.
There endeth the lesson...
Surely the message is, even if you're the most experienced aviator in the world, if the taf says "prob 30 or 40", there's a very high chance that CBs may be encountered anywhere in the vicintity, not just at the airfield.
Anyone who has had the misfortune to experience it will know that a CB can manifest themselves and out - run most types of G/A aircraft, and will almost certaintly bite you if you are stupid or unfortunate enough to fly in the vicinity of, or, God forbid, inside one.
There endeth the lesson...
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There are plenty more good days for pleassure flying which are more enjoyable than dodging CBs, hail, winds etc
Obviously I'm not suggesting that you grossly exceed your limits, but if you use your understanding of the weather, and you think about your alternatives, and you're constantly watching the showers and thinking about which direction they're moving (they always follow the wind), it is perfectly safe to fly on days like today.
In fact, by ruling out these days you're missing out on some of the best visibility (a direct consequence of an unstable atmosphere), and you're missing out on seeing the awesome, powerful beauty of the weather.
I used to rely on having a carefully planned plog with precise headings and timings on it, but I've now learnt the important skill of being able to make up your plan as you go along. Try it on a day when the weather is non-threatening: go up and fly around with no pre-flight route planning at all, just estimate headings. Prove to yourself that it works, then you can use that skill to steer around showers. It's easy!
I think some may be getting or sending the wrong message.
The message I'm trying to put across is that if the Metform 215 says "ISOL" CB's, combined with nice 30km+ visibility, you'll be able to avoid the CB's by the required margin if you keep yourself flexible. I don't think anyone's suggesting flying through or under the darn things, or even clipping the edge of one!
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and I think some maybe propogating unrequired fear.........
I flew today with cells of CB's all over the place. Went to Wickenby to collect my children, flew them out to lunch and flew them home again before flying back home myself. Spent the whole day dodging Cb's and rain storms and at one stage had to hold off for 10 mins before I could land due to big rain and hail storm straight over the runway. Shows the really power and beauty of nature and stunning viz!
Guess what, both engines are still where they should be and my children had a great time and not a spilt drink between them.
If we only ever went flying in this county when the weather was "perfect" we would spend most of out life with our eyes cast skywards.
As has been stated here, use ALL the available sources of weather and your personal judgement which will grow with experiance to make the appropriate calls adn don't be put of by clubroom theory that all CB's are dangerous and will kill you. When they all start joining together into one giant 100mile wide storm is the time to sit on the ground. rest of the time fly round them!
I flew today with cells of CB's all over the place. Went to Wickenby to collect my children, flew them out to lunch and flew them home again before flying back home myself. Spent the whole day dodging Cb's and rain storms and at one stage had to hold off for 10 mins before I could land due to big rain and hail storm straight over the runway. Shows the really power and beauty of nature and stunning viz!
Guess what, both engines are still where they should be and my children had a great time and not a spilt drink between them.
If we only ever went flying in this county when the weather was "perfect" we would spend most of out life with our eyes cast skywards.
As has been stated here, use ALL the available sources of weather and your personal judgement which will grow with experiance to make the appropriate calls adn don't be put of by clubroom theory that all CB's are dangerous and will kill you. When they all start joining together into one giant 100mile wide storm is the time to sit on the ground. rest of the time fly round them!
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I'm with dmjw01 - I flew today and the viz was fantastic - easy to see the weather and run around it, the winds were not too strong. Before t/o, the rain showers and the direction were clearly visible, so I routed to use the clearer areas, could see way ahead whilst airborne, and whilst it was bumpy in patches, it was quite safe - and that's in a Thruster TST!
A
A
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I have to agree about the weather today - my first flight of the year and was lovely! Fantastic vis, bit bumpy but could see any showers miles off.
Great to be back in the air.
Called up missis D&O before driving home and she was p*ssed off it as it was one of the showers was over our home and she could get out in the garden.
I do agree about the TAF/ Metform discussions, it took me a while to really understand what TAFs are saying.
Great to be back in the air.
Called up missis D&O before driving home and she was p*ssed off it as it was one of the showers was over our home and she could get out in the garden.
I do agree about the TAF/ Metform discussions, it took me a while to really understand what TAFs are saying.