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-   -   Would you fly below this cloud? (https://www.pprune.org/private-flying/516536-would-you-fly-below-cloud.html)

All-The-Nines 7th Jun 2013 13:34

Would you fly below this cloud?
 
I'm no meteorologist, and I do not know the definitive answer hence why I'm asking, but would you fly a light aircraft underneath a cloud that looks like this? Photos: ATEC Zephyr 2000 Aircraft Pictures | Airliners.net

In all of my flying so far I would avoid something like that with a very large margin. Visibility still looks good through to the other side so I don't think I'd be too concerned about heavy rain/hail at that moment in time, but I'd be more concerned about the potential updrafts. Am I being too cautious, or have I not understood my Met studies too well?

Considering in the UK we're faced with such a mixed bunch of weather which quite often doesn't match the forecasts on the ground, I'd be interested to learn some people's opinion/observations based on the face of it without any further information available to us.

Dave Gittins 7th Jun 2013 13:38

Not if it looked like that.

Of course, it may be that the light or camera setting was showing the cloud much darker than it was.

If it did look like that I'd be wary of updrafts, downdrafts and sudden violent precip of rain or frozen stuff.

Old pilots; bold pilots etc.

piperarcher 7th Jun 2013 14:18

Its hard to make a judgement. I wonder if the fact that the flash has fired in the cockpit (well, it looks that way anyhow), and if the photograph has been processed in Photoshop or similar, leads to the effect it has. That cloud looks rather unnaturally black in my experience, and I have edited enough photos to know how you can really change something quite dramatically quite easily. Any similar cloud at 2000 ft could be made to look worse than it is. Compared to the light beyond the cloud, it looks strangley dark in the foreground.

I know you dont have them, but I'd be wanting to look at Metar's, TAF's, F215 forms and or synoptic charts to know if it really was that bad.

Its definitely wise to be cautious, and to stay well within your own personal, aircraft or license limits, and with time and knowledge make more reasoned judgements about weather anticipated enroute. Once you get beyond the PPL theory, there is a whole host of Apps / Websites that will give reliable and superior information on weather.

I wouldnt look at photos like this though and be put off.

Jetblu 7th Jun 2013 14:27

I would be more put off in that vicinity with no artificial horizon within the panel.

gasax 7th Jun 2013 14:53

I'm with Piperarcher on this one. There is quite a lot of glare on the black cockpit surfaces, which will cause the underside of the cloud to appear to be very dark.

Given the comparative brightness on the horizon I suspect this is all about how the pixels and eexposure have been treated, not a thunderously pitch black CuNib.

If it were genuinely that dark - not a chance, but I suspect it is no worst than the average large Cu on one of those mixed days.

All-The-Nines 7th Jun 2013 15:02

So the consensus so far is that if it did look like that you definitely wouldn't go near it, but in this case it's much more likely a mixture of the photo exposure along with contrast/levels editing in Photoshop afterward?

I've actually studied and passed ATPL Met at 98%, it was the one exam I genuinely studied long and hard as in my mind it is one of the most critical - I would not rest until I understood each subject and I found lots of useful information through Simon Keeling's weather website Weatherweb TV. But that may be why I'm being extra cautious on the face of it, as opposed to someone that may not fully appreciate the dangers involved.

All-The-Nines 7th Jun 2013 15:06

Flicking through the photographer's other photos, you come across this one presumably taken shortly after on the same day Photos: ATEC Zephyr 2000 Aircraft Pictures | Airliners.net.

It looks like the said storm cloud from the first photo is the one seen over on the horizon.

JW411 7th Jun 2013 16:19

Reminds me of an afternoon at the gliding club I used to help run in my spare time many moons ago. One of my friends had an old pre-war German 2-seat glider called a DFS Kranich. I took one of our solo pilots flying in it and it was such a hot day that we were flying it with the canopy off.

We got underneath such a cloud and we were climbing like a train and the bottom was getting blacker and blacker. I suggested to Charlie that we moved off out of the way but it was too late. Charlie was used to flying gliders with powerful speed limiting airbrakes and not plywood balloons with tiny ineffective spoilers.

I took control as we got swallowed up in the blackness and finally emerged out of the side of the cloud fortunately with the wings level and still the right way up. We were both very wet.

So, unless you really intend to go into the cloud with a full set of working instruments, I would suggest going round the outside by a sensible margin.

mad_jock 7th Jun 2013 19:59

I would fly under it no problems.

Because its not a storm cloud.

Its a photo effect linked in with being ornagraphic lift cloud and they are shooting the slot.

Halfbaked_Boy 7th Jun 2013 20:45

I must be honest, I'd probably man up and go for it.

If hail started peppering the airframe like so many shotgun pellets, I'd possibly turn round, if my testicles allowed me to.

phiggsbroadband 7th Jun 2013 21:10

If you look at the ground about 1 1/2 mile ahead there is some sunshine, and he does seem to be turning that way. Then further on there may be brighter weather in store.

Slopey 7th Jun 2013 23:35

Is the TC indication weird in that photo, or do you think he has a bit of bank on - I can't really tell. If he's doing about 140 knots, would he not need a 20+ degree bank angle for rate 1?

flybymike 8th Jun 2013 00:55


ornagraphic... they are shooting the slot
MJ has come up with another unique contribution to the English language.
Stay away from those websites Jock. It turns you blind.

CISTRS 8th Jun 2013 03:24

It's not really a good idea to scud along at cloudbase. You can't see the other guy doing the same thing.

I would give myself say 200 feet of clear air, if terrain clearance allows. This situation looks a bit marginal in the photo.

India Four Two 8th Jun 2013 06:12


Is the TC indication weird in that photo
I thought the same thing. Assuming the ASI is in MPH, the IAS is 170 mph which at 1600' and assuming a slightly warmer than standard day, would give a TAS of about 154 kts. The TC shows slightly more than rate 1. I assumed Rate 1.2, which equates to a 27 degree bank angle. This is clearly inconsistent with the horizon on the the right side of the photo.

So two reasons not to cloud-fly - no AH and a u/s TC!

PS He would probably be alright though - he's got a Big Pilot's Watch. ;)

cats_five 8th Jun 2013 07:35

Once you are that close to (under) the cloud is far too late to be deciding. Would also add that if they are nice small-medium Cus with a good flat dark bottom you might well find gliders climbing under them.

What makes you think it's orographic cloud?

Prop swinger 8th Jun 2013 12:05

The ASI is in kph. He's doing about 100 knots at 4300rpm with the VSI showing a slight descent (I think the VSI is in m/s, which would mean a descent rate of just over 2 knots.)

Flying that fast with the engine at idle would indicate that the cloud was sucking the aircraft up & he was diving to escape. 100 knots at 4300rpm seems a fairly standard cruise setting for a Rotax 2-seater so its unlikely that the cloud was particularly active & at that speed they will be out the other side in less than 2 seconds.

Is the turn co-ordinator even switched on?

mad_jock 8th Jun 2013 19:01

Slot over the high ground to the left and nose crabbing slightly to the right.

We get that effect quite often up north. The blackness is due to the exposure because of the flash. The bottom of the clouds don't even look like CB bottoms.

It looks to me like its quite moist air which has been lifted and become unstable and formed CU as its banged up against the air getting lifted by the hills.

Its more than likely running south with the sea on his rhs out of shot and that's the first bit of high ground after the air has come off the atlantic and it will be hot ground so churn everything up.

UV 9th Jun 2013 07:09

I def would if I was in my glider...

mary meagher 9th Jun 2013 15:48

High pressure day; cumulus clouds are squashed up against the inversion and spread out, killing the lift as sun no longer strikes the ground .

Low pressure day, probably no inversion, nothing to squash the cu and they just grow and grow and turn black ..... and later in the day may generate an interesting cu nimb, with off the scale lift....

Which I experienced in Russia....I was just tucking under the edge, the rain was going up instead of down, and suddenly there was a flash and bang. The glider did an uncommanded 180 and we got the hell out of there! All you spam cans don't need to worry, you are flying around in your own Faraday cage. But even airliners ought to be a bit nervous. A K21 glider near Dunstable encounted a flash and bang, and the canopy disintegrated, the wings exploded, and both pilots did not need to eject as there was very little glider left to climb out of. One sprained his ankle on landing, I believe. The other one found the hair on the back of his head had been sizzled. When the wreckage of the K21 was recovered and studied by the boffins, the voltage of that particular lightning bolt turned out to be considerably in excess of the protection built into airliners......


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