Tafs and flying today

[Skyseeker]

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

[Penguina]

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...

[rednine]

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!

[J.A.F.O.]

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.

[Flik Roll]

I thought that was why you always include Div. arifields...?? Or is that just me...? :E

[Established Localiser]

As they say up North

"If in doubt......do nowt !"

EL

[bar shaker]

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....

[muffin]

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.

[Miserlou]

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.

[niknak]

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":p

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.

[bookworm]

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.

[dmjw01]

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:

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:
[list=1]
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.

[Human Factor]

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..... :ok:

[dmjw01]

PROB30 really means 1 time in 3 the met man will get it right
It's not really a question of "getting it right" or "getting it wrong".

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
That's more like it! A much better interpretation, and I confess it's something that took me far too long to learn. I've thrown away far too many good flying days through not understanding this.

[rednine]

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.

[niknak]

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... :rolleyes:

[dmjw01]

There are plenty more good days for pleassure flying which are more enjoyable than dodging CBs, hail, winds etc
IMHO, that's nonsense! :)

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.
If you mean me, why not say so?

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!

[S-Works]

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!

:cool:

[Algirdas]

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

[down&out]

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. :O

I do agree about the TAF/ Metform discussions, it took me a while to really understand what TAFs are saying.

[Skyseeker]

Thanks very much for all your responses, very interesting. I have to say that Ive always payed more attention to the tafs and not really spent much time on the 215. From now on i will use the 215 more. Problem is if you are navigating in fairly tight airpsace like between luton and heathrow or between heathrow and gatwick, short of turning around and going back there arent many places to hide. Have to say Id rather not go than get stuck in one of those corridors and have to turn round as Id have spent quite a lot of money only to find that i couldnt do what i wanted to do. In a way Id prefer to save the money for a day when i know id be able to complete what i set out to do.


Thanks for your help chaps!

SS

[LowNSlow]

I also was nearly put of by Sunday's TAF but still managed to get to my destination. Took me an hour against the headwind and 40 minutes to get back with only one slight diversion to avoid a chunky big (cb) cloud. as I went around it I was "followed" by a rainbow. Marvellous. Viz was fantastic as well.

Whilst putting the wunderplane away in lovely sunshine I watched a massive cb passing to the East. Turns out that my house 5 miles from the airfield was being deluged with hailstones!

[bookworm]

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 Private Flying terms, 1 time in 3 you'll find one of these looming over your turning point or destination.

No that's not what it means. It means that there is a 1 in 3 chance that at some time during the 5 hour period, there will be one of these looming over a particular place of your choosing. Since the duration of convective activity, particularly with a strong wind, is relatively short, the probability that it will be there when you want to be there is much smaller than 1 in 3.

so either don't fly or be prepared to vary your route or hold-off. ... Flexibility is the key to air power, someone once told me.....

I'd still agree with that 100%.

[Fuji Abound]

Age old wisdom, as this thread so well illustrates, is that if you are not sure then don’t fly. It is a line that is a bit too easy to trot out. If we always followed this approach we would never become more experienced. For example, did you have doubts before your first solo or first solo cross country - but you went. Why? In those situations hopefully you had confidence in your instructor and accepted that if he felt the conditions were good enough you should be ok. In the same way this weekend you might have felt the conditions were a little more challenging than you were use to, and of course it is easy to say I’ll stay in the pub. Instead, have a chat with a local instructor or more experienced pilot, maybe one of them would come along with you, or, rather than setting out on a cross country enjoy a short local flight.

So far as this week end was concerned the conditions were exactly as the TAF’s and regional forecasts suggested in my part of the world. The big Cbs were very well spaced and visible from miles away. These are typical conditions for this type of forecast. So long as you are prepared to change your course it is easy to steer around the more significant build ups and give these a wide and safe berth.

“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”

Saturday and Sunday were typical blustery days. The advantage is that the cells moved pretty quickly and if one happened to be over your intended destination when you arrived it wasn’t going to be long before it moved away so you could afford to linger a safe distance.

Cbs outrunning typical GA aircraft in the conditions we saw over the week end is a new one on me. Am I missing something?

All in all I take your point that you did not want to get boxed in some of the narrow air space around Heathrow and you had a destination in mind which you might not have reached. Given that was your mission you might have found negotiating the cells that much more difficult. My point is that it is always safer to stay on the ground but then none of us would ever fly. I am asking we consider staying within a reasonable comfort zone by properly assessing and understanding the forecasts and the conditions and being prepared, should we wish, to safely extend our experience.

Skyseeker - I wanted to add one more comment having reread your email. As others have said the viz in these conditions is usually brilliant - exactly as forecast. Going to Bristol I could see the bridge from before Lyneham some 40 mile aways. I appreciate the constraints of the London TMA but around Gatwick and Heathrow there is plently of room for avoidings Cbs in these conditions so long as you are not hugging the edge of the CZ and even if you are using the Burnham or Luton corridor the viz is so good you will spot problems before entering the corridor so as long as you are prepared to route around the other side of the CZ rather than through the corridor there is no reason why you should get any where near a problem CB.

[dmjw01]

And of course, if you do find yourself in a tight class G corridor needing to avoid a CB, and the "only" option is to turn around and go home, there's actually one easily-overlooked option that might allow you to continue to your destination: Push your button and request a zone penetration. Tell the controller that there's a CB getting in your way and you'd like to nip into the zone for a few miles and back out again, and there's a reasonable chance you'll get the clearance you need.

It's not an option that you can rely on of course, but you should stay positive and give yourself every chance of safely completing your intended journey.

[Fuji Abound]

"It's not an option that you can rely on of course, but you should stay positive and give yourself every chance of safely completing your intended journey."

Clearly you would not want to rely on a zone clearance in your pre flight planning however I think if I found myself in a corridor with no where else to go to avoid a thunderstorm but through the zone I would pretty much expect to be given the clearance particularly if I had said why I had asked for the clearance. If I still didnt get the clearance I suspect a pan might even be the order of the day - failure to avoid a thunderstorm is definitely in the category of endangering the safe conduct of the flight!

[rednine]

Be ready for Pan calls? Oh dear oh dear - we shouldn't be flying in this weather really should we?

[Fuji Abound]

Rednine - clearly you should not because you have missed the whole point of the debate.

[S-Works]

what weather? a few clouds and a bit of rain.

[rednine]

I am sorry but I would have to disagree. This debate is about safety and thinking about the weather.

Yes, OK, you can take chances and play the probabilities game and you can win.

However, you can also lose and the consequences of losing are severe!

I have been reading all this with interest and I would still suggest that as we are PPLs and doing this for pleasure and fun then we must be very cautious with the weather.


To justify my stand I ask you to look again at the post where the use of PAN calls is possible. Common sense, to me, would dictate that we should not even consider flying when this might be an option!!!

What are we trying to gain experience for? Again this is pleaseure and my view is that the weather is one of the biggest killers and I treat it with the UTMOST RESPECT.

I showed this correspondence to my airline captain friend who found some of the views amazing! His view, after 35 yeare flying was "I would be on the ground and not even considering flying".

His other comment worried me a little when he decribed some PPLs as "cowboys" - wonder why?

For me, I agree with him and you wont catch me getting experience up nera CBs with a TAF like that - give me a nice clear day where I can enjoy and have as much safety as possible and achieve what I set out to do.

[boomerangben]

This thread is really more about experience and personal limitations. Each of us will interpret the weather differently depending on experience and type of flying undertaken. There is no right or wrong answer. It is only natural for an experienced aviator to consider those TAFs as being good enough for flying, in the same way as the orginal poster found it natural to cancel his/her plans. 6 years ago I would have not flown in those conditions. I was flying on Sunday, and have been flying in far worse. But that is what experience does for you. Those of us with plenty of experience should stay off the soap box when giving advice to those with less experience.

As for the airlines which ignore the PROB bits of TAFs..... that is scarey. Even if you do have autoland.

[PilotOnline]

As I sit in my office looking out at the sky (a somewhat frequent occurance) it is now overcast. On Sunday, had it been so, I'd have stayed on the ground as I would not have been able to see the CB's and therefore avoid them. The cloud cover on Sunday was very broken between Denham and (as far as I went) DTY during my flight time window, which meant I could see where any of the CB's were in that area, where large cumulus were forming etc. I checked the 5,000 and 10,000ft wind before I left to see which direction and how fast they would be moving. I could therefore maintain a significant distance from any of the CB's and enjoy a lovely flight in the local area. Again, with flight planning, I had at least 3 alternates which at no time were obstructed by weather.

To the poster's original comments, I can't fault you at all on deciding not to go. If you were unhappy with the weather and your sole purpose of the flight was to fly that particular route, then yes you probably would have had to turned back or gone a different way depending on what time you were due airborne. Far more limiting in my opinion was the wind at Denham on Sunday. At the end of the day, you assessed the weather, made a decision and stood by it... that's a good thing!

[Fuji Abound]

"Yes, OK, you can take chances and play the probabilities game and you can win."

There is a probability of flying into an embedded CB. We dont fly in those conditions. There was no probability of flying into a CB in 30K visibility over the weekend unless you were blind (and probably stupid as well).

"I have been reading all this with interest and I would still suggest that as we are PPLs and doing this for pleasure and fun then we must be very cautious with the weather."

Neither P stands for pleasure. I always enjoy my flying but that doesnt mean it is always purely for pleasure.

"What are we trying to gain experience for?"

Some of us will take on longer flights. It is likely however careful we are with the TAFs and AFs we will at times encounter weather that is different from that predicted. I would be very concerned with any pilot who was no longer gaining experience from his flying. Only recently I encountered a weather event with no CBs forecast or around which I had never come across before. I am glad I now have the experience of those particular conditions. I think it makes me a better pilot.

"I showed this correspondence to my airline captain friend who found some of the views amazing! His view, after 35 yeare flying was "I would be on the ground and not even considering flying".

His other comment worried me a little when he decribed some PPLs as "cowboys" - wonder why?"

I was flying with a commercial pilot over the weekend. He is with BA. We had a great time. Safety was never an issue. I wonder whether your friend was actually aware of the conditions or enjoying a well earned rest in the pub.

You seem to imply there is some magic in being a commercial pilot. The magic is in the 35 years and there are a number of contributors on this forum who have been flying for that long in GA. I suspect they might be rather offended to be referred to as "cowboys". However since your friend was once a PPL himself maybe it takes one to know one?

:ooh:

"To justify my stand I ask you to look again at the post where the use of PAN calls is possible. Common sense, to me, would dictate that we should not even consider flying when this might be an option!!!"

Have you really read the thread. Every flight should start with the possibility of making a PAN or MAYDAY. Hopefully it never happens. The point was never that you should plan a PAN call for weather avoidance, rather a debate about wether if you were amazingly refused a zone clearance due to weather a PAN call would secure the clearance you sought.

[IO540]

I know from a UK Airbus pilot that under their procedures they ignore a PROB30 TEMPO in a TAF.

But then an airliner has a lot more options when it comes to icing conditions, and has weather radar, and ready access to any available bit of air they ask for.

As Fuji says, it is absolutely right that one should not avoid flying just because one is "unsure" or something like that. That just leads to giving up flying. Any go/no-go decision should be made on technical reasons alone.

I am no weather expert but as regards forecast CB activity, if I had to fly in the area then I would look at the lowest forecast bases, subtract a bit for good measure, and if the result is still well above the MSA I would go. So if the CB bases are forecast at 3000ft, I would assume they could be at 2500ft, and plan the flight for 2000ft and ask if that is well above the MSA. The MSA does count even on a VFR flight because the vis is likely to be next to zero in a heavy shower. In reality one would fly around a heavy shower but one has to have an OUT option of which a 180 back home is the least favoured.

I would not set off into IMC (i.e. without a VMC on top option, due to airspace etc) if there could be embedded CBs; my stormscope is pretty good but it won't see them until they get pretty serious.

One wouldn't do a scenic flight with a bird on a day like that, though :O

[S-Works]

Blimey, rednine you strike me as being a bit afraid of the weather. I assume you are either very low hours or very cautious. Neither of which I am knocking. If you are high hours then you must be doing some pretty dull flying?

We all make our own calls and those calls are based on experiance. There are a lot of us on these forums who have a significant number of hours and base our judgements of when to fly on this experiance. My airline friends (some of whom I have more hours than) do not judge my decisions. I also think it is insulting to a lot of the experianced aviators here to assume because they have chosen not to fly 350 drunk chavs around for a living that they are any less professional as aviators. Some of us prefer to have proper jobs that pay vast salaries so we can buy more toys!

So I make my point again, it was just a few clouds and some showers and no big deal.

[Maxflyer]

Strikes me that one of the most important lessons here is not how to read a TAF or 215, but what is your own level of experience. I am keen to fly when time and money allow and I am now in the fortunate position that I have access to a Cessna owned by another PPRuNe contributor. I have flown with him in conditions that on my own I would not have attempted. The strange thing is that we had a good time, flew safely and for my part learnt a great deal. This has added to my experience and given me a new confidence to fly at a time when otherwise I would be grounded. It must be noted that I will still rely on all weather data to gain an informed idea of what to expect. Equally, I would still stay on the ground at times my friend would choose to fly, but that is a personal choice based on my level of experience compared to his.

[rednine]

Well actually, 22 years experience and about 1100 hours! Does that help? Guess we will all have to stick to our opinions then eh?

However, you are quite right in that I am terrified of the weather - actually I am terrified of anything that if mistreated will kill me!!


Rednine

[Fuji Abound]

"Well actually, 22 years experience and about 1100 hours!"

So tell us in your 22 years have you never flown on an occasion when the viz was +30K and isolated CBs. Are you saying that if any CBs are forecast you would never fly or if you are not saying that then in what circumstances would you fly? Are you instrument rated?

I am genuinely interested.

[kookabat]

Just to weigh in to this particular debate... I've recently got my PPL, only have about 80 hours in the logbook. Had a shocker of a time weather wise in getting this far, I cancelled a LOT of navs based on the forecast when, of course, it cleared up later on in the day. Then again, there were other times when it certainly DID NOT clear up.
On a few occasions, while hanging around the flying school because the weather was crap and I wasn't going anywhere, a number of Cherokees from a particular flying school at which a fair few of my mates were learning popped up and appeared over the nearby escarpment - with, as I later found out, those mates of mine usually as solo students on board. They all had around the same amount of experience as me at the time, so if they could do it then why didn't I go?
The answer is that they were (and still are) training for CPLs and bigger and better things. I'm not. I fly purely for the hell of it. If it isn't fun, there's no point. I have precisely no commercial pressures on me completing a flight or not. And that's the way I intend it to stay.

It's always better to be down here, wishing you were up there, than up there, wishing you were down here!

Adam

[rednine]

Kookabat

You and I are in agreement and we have no pressures and do it for fun!

Just to confirm that I have flown many hours in IMC but in carefully selected conditions. I have also flown in CBs and have experienced TSs - its not where you want to be!!

Been there, done that and got the T shirt!

Never again if I can help it!!

[S-Works]

ah well 1100 in 22 years shows a cautious streak. Some of us have flown that in the last 3 years and so I think that respect for the weather is probably tempered with that experiance.

I am not knocking your choice's we all make ours based on our experiance and currency.

I have flown around quite a few Cb's and recall a very memorable vectored ILS in Guernsey a year or so ago with Ludwig that did have me wishing we were else where. Black as night and the airframe sounded like it was being sandblasted. But we survived to tell the story and leant from it.

I do fly for business but as I have no work ethic have no pressures either, but that does not stop me expanding the envelope of personal experiance.

[Fuji Abound]

Rednine

I am sorry I just do not understand.

I can understand people being selective about the conditions in which they fly - no problem at all with that. I can understand pilots being cautious - thats sensible.

I cant understand the stance you have taken.

You have flown in CBs and TSs. OK well that is a lot further than anyone on this thread has discussed. I dont suppose for one moment it was where you wanted to be. Thats not what the question was about.

The original questioner was asking, as I assume a relatively inexperienced pilot, whether conditions over the weekend were suitable for flying safely given the TAF and AF forecasts suggesting a 30% prob of CBs and +10k vis. I think he is entitled to an informed reply from pilots with a good level of experience.

You suggested that pilots who fly in these conditions were "cowboys" and a commercial pilot friend would "not even consider flying"

I simply do not understand given your experience how you could reach that conclusion. I also do not think it is born out by the facts. There were plenty of other pilots flying, a lot of instructors up with students, and I didnt here a single pilot ask for a weather diversion. Were they all "cowboys"?

With your level of experience are you seriously suggesting there are particular problems avoiding CBs given these conditions? If you are what specific problems do you have in mind and why?

[rednine]

Wow!

almost 400 hours per year as a PPL - thats some experience! Wish I could afford that - thats almost 10 hours a week - fantastic ! However, guess I will have to stick to my meagre flying.

However, perhaps that just illustrates the point that you have had a massive experience and as the average PPL flys about 15 hours a week then we must urge caution - you are an exception with your mass of experience and we don't want less experienced guys thinking its OK to have a go!

But OK for someone of your experience and skills,

Good luck with the flying!!

[S-Works]

Never considered myself to be experianced but I do a good amount of flying. Owning an aircraft and not having to share it certainly helps!

Tommorrow I am off to Alderney for the night and Friday to collect the twin then a weekend in France. I am fairly sure that we might encounter a few storm cells over the course of the week!

:cool:

[dmjw01]

It's incredible that this thread has developed into this!

I don't understand those who keep trotting out the irrelevant statement that "the inside of a CB is not a place you want to be". Well, duh! Can somebody explain to me how do you end up inside a CB when the vis is 30km+, the cloudbase is decent and the CBs are isolated? Personally I fly with my eyes open, not shut. ;)

Also, people keep saying "but we do this for fun, so why fly in these conditions?" To which I say: 30km+ visibility is fun. The CBs are miles away from you; just keep it that way and enjoy the lovely conditions!

Regarding the airline captain who said he wouldn't fly in such conditions: The airline pilots I've spoken to fall into two categories. There are those who live, breathe, eat and drink aviation in all its forms and use any excuse to go flying in their spare time; and then there are those who have no interest in flying except as a way of paying the bills. I'd bet that particular captain fell into the latter category, in which case he probably hasn't flown a light aircraft for years - so he's making the right decision not to fly based on his lack of relevant experience.

Jeez... Yes - CBs are dangerous. They're evil buggers - nobody's disputing that. But when you're driving on the roads, the cars coming the other way are dangerous too - but you can see them and avoid them. On a decent day such as the one we're talking about, you can see and avoid the CBs with great ease.

[Maxflyer]

Of course you can always use the ADF as a cheap stormscope to point out where those cells are hiding!

[Miserlou]

NikNak,
PROB30 TEMPO is not a very high probability.

TEMPO means a temporary change the total duration of which does not exceed half of the tempo time period.

Prob30 means a 30% chance of.

So to correctly interprete the Cranfield TAF, there are rain showers forecast for a total period of less than 2 hours between 1300z and 1700z which will reduce the visibility to 7km from Cumulo-Nimbus clouds whose bases, at 3000', cover between half and 7/8 of the sky in the vicinity of the airfield. There is a 40% probability (or less than half of these showers) that these showers will reduce the visibility to 4km and be heavy rain showers with thunderstorm and hail.

So you could be looking at one huge cell which closes in for half of the afternoon or, more probably, lots of showers passing through but for not more than 2 hours in total, 15 minutes per cell per hour, perhaps.


Just to confirm and clarify,
PROB TEMPO=Disregard,
TEMPO or PROB30-40 alone, Showery or trancient (TS and SH)= Disregard.
Persistent conditions, haze, mist, fog, precipitation=Applicable, mean wind shall be within limits, disregard gusts.

[IO540]

Of course you can always use the ADF as a cheap stormscope to point out where those cells are hiding!

That's a very old one which refuses to go away, it even gets repeated by ATPL instructors who should know better, and like a lot of stuff that keeps coming up in this game it's almost completely wrong.

An ADF will be affected by nearby CB activity but not in any manner that's predictable enough to be of any use.

Even a WX500 or similar stormscope cannot be relied on for embedded CB penetration. What one can reasonably rely on is that if it IS showing a cluster of strikes, the ride is definitely going to be very rough (done it myself) and that heading is best avoided, and if one can't avoid it then one has to slow right down. But an absence of indication does not mean absence of moderate or severe turbulence. Preferably do this without the bird in the RH seat :O

[Miserlou]

I've been away for a few days and have just read more thoroughly the middle pages. Now for some trouble!

RedNine,
Your mate sounds like the perfect example of why such a lot of airline pilots are such p*ss poor SEP pilots. Many of them maintain SEP priviledges but not currency and suddenly it's a different world sitting alone in a single engined piston aircraft, VFR in uncontrolled airspace. They are used to having everything, all the knobs and whistles, and a sparring partner to match.

Back to that TAF, there's nothing wrong with 7K viz in rain either especially with the base at 3000'. Bumpy perhaps but still legal and often you can see the light on the other side before you go in.

TS you want to avoid, of course. A very conservative rule would be the number of thousands of feet vertical extension is the number of miles away you want to be.
Don't confuse CB and TS; the difference will come to you in a flash.

[Wrong Stuff]

I'm another one who thinks RedNine is wrong-footed on this. Even if you stay on the ground whenever the slightest bit of poor weather is forecast you're still not guaranteed to never meet anything threatening. Forecasts are just best predictions and there will always be occasions when they're wrong. Anyone with a significant amount of hours will have come across unforecast adverse weather.

This is especially true for longer legs or day trips away as the further into the future you look, the less accurate the forecasts become. Local bimblers may be able to avoid bad weather, but I don't believe most PPLs want to just stay in the local area. Look at any European synoptic chart - the further you travel the more likely it is you'll have to contend with the possibility of less than ideal weather. If you want to do a day trip to Le Touquet what are you going to do when a few unforecast isolated CBs start to build up in the afternoon?

It's much better to have thought about these problems beforehand, worked out how to circumvent them safely and preferably built up real experience of doing so - perhaps with the accompaniment of an instructor or a more experienced pilot - than it is to first come across them when you're not expecting them and you're not prepared.

The cowboys in aviation are the ones who stick their heads in the sand and don't think about how to deal with unexpected problems. I don't see how a pilot who is able to safely plan diversions around bad weather and has a number of backup plans they've thought about beforehand can be described in such a way.