Flight planning with this patchy weather
 

This weather (I'm looking across the middle of England) looks like it presents some breaks in between the gloom. Do most VFR pilots abandon plans during this sort of weather or do they hope to nip out and get down during lulls? I suppose this question is really asking whether UK weather requires one to be opportunistic or is that the beginning of the slippery slope to get-there-itus?

I canned the the cross country part of my flight yesterday. Probably could have avoided the worst of the weather but was not prepared to take the risk. If the gaps would closed up things would have got very tricky.

Still did a little aerobatics though.

Ok as long as….
 

You have enough fuel on board to divert or hold as required. Enough charts and airfield information to divert and know what’s there. Enough time before dark or other factors to get somewhere safely.

The storm cells yesterday were less of a problem because you could see them. It gets more difficult when the cells are embedded in the general clag. Knowing which way the cells are actually moving is useful. A large and active cell that passed over Headcorn yesterday laid down a white carpet (of hail) a couple of miles wide across the southeast. It made it relatively easy to see the direction of travel of the cell.

I think that UK weather requires the PPL to be somewhat pragmatic.

Much of the forecast information will give conditions which are 'conservative' - so frequently either the general situation will be better than forecast or specific aspects of it will be. I often note that the TAFs will oftne make a flight seem unlikely.

But - well there is always a but, now and then the shear variety of our climate will result in really much worst weather than forecast or localised conditions which really mean standing on the ground looking up is the only safe alternative. In about 300 hrs of proper cross country flying, I have made at least a dozen major diversions or U-turns and ended up on the ground omewhere I have no intention of being. I have also had probably a similar number of occasions where I have delayed leaving by at at least a day.

So as a 'dispatch rate' it starts to look like around 10% of my VFR cross country flights have had major alterations - but I do live in Scotland and by cross country I mean in excess of 2.5hrs..

But then even for 'local' flights I have had at least 5 major diversions in around 800 hrs - so approaching a 1% rate when you can simply look out of the window (mainly haar and localised rain / hale / snow).

Just one of these things we have to put up with. Some times you can be lucky with the Wx and get a half-decent break but up my way things have been decidedly dodgy for the past few days; not worth the risk.

If you don't like the weather, wait a while; it'll change :)

It depends on what you want to do.
Generally you can see the cells quite clearly and assuming you are not limited by airspace restrictions, it is easy to detour around them. So circuits and short local flights are OK.
X countries are more challenging, but take a look at the weather radar to see how much space there is in between cells.

In addition early mornings and evenings are best when there is less heat from the sun.

TAFs will always be pessimistic because the forecaster has to throw in anything remotely likely under the PROB30 heading.

The UK F215 is even more pessimistic, throwing in everything including the kitchen sink, and then adding moderate icing in all cloud even if the wx is CAVOK.

So one needs to have a physical look at the actual wx. One can use weather radar, sferics, satellite IR images, etc.

And a quick look at the MSLP chart will give you plenty of clues. The troughs (their actual position is meaningless; the forecaster just draws them in randomly) mean a PROB30 TEMPO of TS, and sure enough for EGKK you now have, for tomorrow,

PROB30 TEMPO 1313/1318 4000 +SHRA

I am no forecaster and would never suggest anybody can beat those who do it for a living, but it's not hard to get a rough grip on what is coming. It's just that in the PPL people spend hours on the stupid slide rule when they could be learning to read wx data presented to them on a plate, using that new fangled method (never mentioned in my PPL) called the internet :)

A while ago I knocked up this pic, largely from the POV of high altitude IFR. It is self explanatory. One interesting thing I found repeatedly is that you get TS where there is a change from a cold to a warm front.

I wish real charts were marked up like that - wold make things a bit easier :}

Yup, loved the prob 100 really **** WX. I mean..no decode necessary or anyfink...

If I have to go anywhere a significant distance VFR and the weather is crappy I start out for the nearest airport more or less in the direction I with the the idea I will takeoff and have a look. If after takeoff I don't like what I see I just go back. If I get to it and things still look doable I set course for the next aiprort and repeat the process. There have been many days when I made 500 miles when I though I would be lucky to make 50.

But you have to have hard no go criteria. In other words you have a minimum altitude that you will not descend below. Anytime cloud forces you lower you turn around. The same for visibility.

Ive had my IMC test at netherthorpe scratched last two days due weather, very frustrating!!!:ugh:booked for later today, still look marginal last time i looked but i have icing concerns but thats whats makes this counrty great the varied weather......yeah right.

What altitude are you flying at?

Not sure today, my examiner may have changed plans, yesterday was 2 holds booked at doncaster 3500 then ILS. Other inbound traffic was diverting round weather yesterday.

Just want to get it knocked off now I am getting bored under the visor and ive got too much going on elsewhere to give it 100%

This is a nice pic, from a couple of days ago

http://www.zen74158.zen.co.uk/aviati...image.ashx.gif

From bitter experience the oft quoted remark "better being down here wishing you were up there...." is worth repeating

Peterh337,

Thanks for your links, I am just going through MET theory study for my forthcoming exam, and will start the practical flying soon. However I wanted to start getting use to MET planning from the start. Your links are most valuable. :ok:

I find MET an interesting subject, but quite a lot of information to get through and understand. :ooh:

For someone wanting to get a good practical grasp of weather post-PPL, does anyone recommend any follow on training. I know Simon Keeling runs such courses. Are they effective? The Met Office seem to do some as well.

IME, IMHO, they are not helpful because they just cover the same old met theory, which is almost impossible to use for anything practical because there is no website which can give you the data to "plug into" that understanding, so to speak.

That was my gripe with the JAA IR met also. Completely useless for understanding weather, I found.

What is needed is knowing how to directly use the various internet-sourced weather data to make practical go/no-go decisions. I am not aware of anybody doing that.

That's a really good question - weather is one of the things I feel I have the weakest practical grasp of post-PPL.

This is why I think the way to approach this is by looking at hypothetical mission scenarios, in a classroom setting, using internet data.

It is completely wrong to think that one can (on any significantly reliable basis) outforecast the forecasters. Yet the way met is taught everywhere is just that... they teach you about polar tropical and maritime tropical etc etc airflows. I always find that stuff goes right over my head and I cannot see any way to relate it to reality. What matters at the end of the day is the tafs, metars, the frontal picture, radar, etc.