Primarily for general aviation discussion, but other aviation topics are also welcome.
#1877204
PeteSpencer wrote:Top tip for @Supercat :… protected from snarky and often unhelpful responses such as have appeared already on this thread.
:


You must be reading a different thread to me Pete. I don’t see any snarky or unhelpful comments.
There are a few bemused responses along the lines of ‘these are basic questions that should have been covered in your training’, that’s all. Nothing wrong with that, particularly if they encourage the OP to go and study Met more.
#1877208
Supercat wrote:For instance, having checked the weather, metars and TAFs, would you go out for an hour or two's nav if it was overcast but otherwise benign? ( I know that most of the UK is like this 65% of the time...) I seem to be worried that the cloud level might drop and I'd be stuck. This might not happen in real life :D


I didn't answer this one earlier. Cloud base/ceiling can, of course, drop when the synoptic weather situation changes, i.e. when a different air mass nudges in. This should be apparent from the TAFs. However in my experience, in the absence of such a change cloud bases tend to rise rather more often than they descend.

My naive model of this is of a boundary layer (lowest few thousand feet) whose temperature is influenced mostly by the temperature of the surface. As the sun gets to the land during the day, the boundary layer warms, which means that the temperature and dewpoint tend to widen from ground level up (like ripping open a tear on the sounding), raising the condensation level at which you find cloud. By contrast, when the heating stops in the evening, the cooling of the surface layer tends to cause condensation near the surface, which means that your enemy tends to be fog and mist rather than simply a lowering cloud base. But there are obviously exceptions. Maybe a proper meteorologist can comment.
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By PeteSpencer
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#1877216
lobstaboy wrote:
PeteSpencer wrote:Top tip for @Supercat :… protected from snarky and often unhelpful responses such as have appeared already on this thread.
:


You must be reading a different thread to me Pete. I don’t see any snarky or unhelpful comments.
There are a few bemused responses along the lines of ‘these are basic questions that should have been covered in your training’, that’s all. Nothing wrong with that, particularly if they encourage the OP to go and study Met more.



I suppose ‘it depends ‘, as the late Professor Joad would have said, ‘ on what you mean by snarky’ (And unhelpful):

‘ well your instructor should have told you this’. and ‘ you must have studied this already and should know it as you’ve done the met exam (I paraphrase)’

are snarky and unhelpful in my book . :wink: :wink:
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#1877226
bookworm wrote:I didn't answer this one earlier. Cloud base/ceiling can, of course, drop when the synoptic weather situation changes, i.e. when a different air mass nudges in. This should be apparent from the TAFs. However in my experience, in the absence of such a change cloud bases tend to rise rather more often than they descend.

My naive model of this is of a boundary layer (lowest few thousand feet) whose temperature is influenced mostly by the temperature of the surface. As the sun gets to the land during the day, the boundary layer warms, which means that the temperature and dewpoint tend to widen from ground level up (like ripping open a tear on the sounding), raising the condensation level at which you find cloud. By contrast, when the heating stops in the evening, the cooling of the surface layer tends to cause condensation near the surface, which means that your enemy tends to be fog and mist rather than simply a lowering cloud base. But there are obviously exceptions. Maybe a proper meteorologist can comment.


Thanks for the explanation, I pointed in my earlier comment that unexpected fog/mist AND low clouds is what worries me when flying VFR in Oct, I can go now and sleep happy about “low clouds” late afternoons, well as long as I have load of fuel and Biggin Hill or Dunkeswell are open and sit above the fog blanket :lol:

Indeed, it’s from the uneven shape of temp/dew spread profile: the condensation on the tiny boundary near the surface will surprisingly push the cloud-base higher, this is not captured in a simple linear model of temp/dew spread profile vs cloud-base…
By TopCat
FLYER Club Member  FLYER Club Member
#1877231
My concern about this thread, and indeed the reason for my response early on suggesting that the OP summarise what he does know, is that threads like this generate enormous numbers of replies, many helpful, and some conflicting.

And none of which, no matter how helpfully intended, will be anywhere near complete or structured enough for a recently qualified pilot to acquire the knowledge (s)he needs on such a vitally important question.

I don't read any of the replies as snarky (ironically, other than the one from the OP that I and @lobstaboy have commented on), and my first response was certainly not intended as such.

However, I did read the OP with a certain amount of alarm, as it suggests to me a woefully deficient training course.

If someone has got to the end of a PPL course without (a) knowing enough about weather to be confident of solo flights in benign conditions, and (b) where to look for more information (there a whole book on Air Law and Met, for instance, as a starting point - I'd be very concerned if a new pilot hasn't read and digested most of that), then something has gone wrong.

Whatever that something is, I very much doubt that a long thread with useful titbits will put it right, no matter how well-intended.
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By foxmoth
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#1877244
lobstaboy wrote:In practice you’ll find it helpful to give yourself some simple wx minima. Say 2000’ cloud base and 20k viz.


Sensible minima are fine but if you use these you will hardly ever fly in the UK! Most forecasts /METARs don’t give viz over 10k anyway and you can set off with these conditions then find it way worse when you head home so the fly towards a front is sensible. As for icing, don’t fly where you might get freezing rain and don’t fly in cloud and you should be OK, if and when you do any sort of IR course this should be discussed further.
#1877253
There is lot of “myths” around when one gets their PPL, these goes away when one gets better understanding of weather, more qualifications and more experience

Someone quoted this document which seems to be useful for someone who just started to read

https://www.astralaviationconsulting.co ... rces/icing

AFAIK, you have to look very hard to find SEP airframe icing accidents in UK, maybe 2 or 3 in last 50 years? (obvious reasons: more awareness and it’s easy to avoid: flat terrain with low MSA, moderate temperatures and ability to fly off airways and outside airspace on IFR),

People take data from winter flying in Colorado or Alaska and make a whole dinner out of "airframe icing" or "FIKI aircrafts", in the other hand lot of engines certified in Florida/California will fall out of the sky in UK moist air and will require religious carb icing & alternate air application and awareness, it’s bad enough that CAA did write & send an AIC about it:

https://nats-uk.ead-it.com/cms-nats/exp ... 077_en.pdf

Not down playing the risks or inflating them just understanding things better helps to get a sense of those that matter and those that don't … I think it's better for VFR PPL pilot to spend more time concentrating on carb/engine ice (maybe hundereds/thousands of accidents/incidents) and remain VMC and let "airframe icing" sleeps :wink:
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By VRB_20kt
FLYER Club Member  FLYER Club Member
#1877278
Fly in decent weather and fly often. You’ll gain experience. As that happens your personal minima will begin to lower. Then one day you’ll wish you were on the ground and roll back your minima a bit for future flights.

Just remember
- because something is legal doesn’t make it advisable.
- You don’t have to land at your intended destination.
- The weather is rarely exactly as forecast

There’s some interesting advice in the responses you’ve had. You have your PPL ticket to learn. That doesn’t prevent you from flying with an instructor or mentor. Happily the next hundred hours or so are rumoured statistically to be some of the safer you will ever do.
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By TopCat
FLYER Club Member  FLYER Club Member
#1877393
Cessna571 wrote:Well, either that scared off the OP or he didn’t want to answer any questions.

Or he's AFK, reading books on Met. Let's hope, eh?

The OP always seemed to me a strange question.

Pilots are smart people, they very rarely ask dumb questions. "How do I figure out if the weather is ok to fly?" (I paraphrase a little) is such an enormous question that it struck me as a bit odd.

I didn't expect this thread to end all that well. I may be wrong, of course - it hasn't yet.
#1877586
The OP was asking about “airframe icing”, it’s a very technical subject and some of useful answers and excellent links were posted in the first page

He was not asking for “life lessons” :lol: I personally take these from Uber drivers, they are far more knowledgeable when it comes to this :D