flying under CBs is OK
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flying under CBs is OK
IO540 made this comment on another thred.
I would like to throw that statement open to the whole Private Flying Forum and see how many people agree with IO540 that flying under or through CBs is OK.
Regards,
DFC
I would like to throw that statement open to the whole Private Flying Forum and see how many people agree with IO540 that flying under or through CBs is OK.
Regards,
DFC
Sub Judice Angel Lovegod
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There is no absolutely correct answer, as there are CBs and CBs, but the hazards of flying beneath them include:
Hail damage
Lightning strike
Microbursts
Severe turbulence
Severe icing
Radio interference
Temporary blindness
Tornados
...each to his own.
Hail damage
Lightning strike
Microbursts
Severe turbulence
Severe icing
Radio interference
Temporary blindness
Tornados
...each to his own.
Humus Motor
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Sirs or Madams, I have no wish to get into a personal argument between folks on this forum .. but after, well, nearly 40 years flying, you might forgive me for throwing in a few observations ...
I have the pleasure of flying both a vintage light aircraft and pretty high performance jet airliner. I also have the responsibility of teaching said jet, both in the simulator and in the aircraft. Part of the sim syllabus is a demonstration of the downdraft potential under large Cbs, which can easily exceed the vertical performance of the aeroplane, and for your info, we can often squeeze 5-6000 ft per min. rate of climb from this aircraft if it's reasonably light. There are some scenarios where it is impossible to escape, despite being in clear air with the runway in sight. This is why my colleagues and I hold off when there are Cbs on the approach or the take-off path.
Call me old-fashioned, but personally, I would rather eat my own leg than deliberately fly my light aircraft under a Cb, wherever the MSA is.
Of course, you will get away with it for a very large percentage of the time. But one day................
I have the pleasure of flying both a vintage light aircraft and pretty high performance jet airliner. I also have the responsibility of teaching said jet, both in the simulator and in the aircraft. Part of the sim syllabus is a demonstration of the downdraft potential under large Cbs, which can easily exceed the vertical performance of the aeroplane, and for your info, we can often squeeze 5-6000 ft per min. rate of climb from this aircraft if it's reasonably light. There are some scenarios where it is impossible to escape, despite being in clear air with the runway in sight. This is why my colleagues and I hold off when there are Cbs on the approach or the take-off path.
Call me old-fashioned, but personally, I would rather eat my own leg than deliberately fly my light aircraft under a Cb, wherever the MSA is.
Of course, you will get away with it for a very large percentage of the time. But one day................
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Under "large" CBs - very definitely one to always avoid. Only once experienced a micro down burst (and in fact it wasnt any where near a CB) and never again. A very unsettling experience.
However as Earthmover says there are CBs and large Cbs. I suppose as always it does depend on the actual size of the CB.
However as Earthmover says there are CBs and large Cbs. I suppose as always it does depend on the actual size of the CB.
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You have to decide on what cause a CB I think. A CB in a big cold front then maybe a problem but a bit of hot air from a hair dryer then I think is ok. But you stay away from CB in France. Those French CB they very tricky guys.
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There seems to be some misunderstanding as to what a Cb is. Cumulo=fluffy cloud, nimbus=rain.
When it starts to rain then you have the dissipating stage which is the stage where microbursts and the rest of the Pandora's Box is unleashed. You don't want to play in this playground.
Cumulus are bumpy but rarely worse than uncomfortable.
Towering cumulus are somwhat worse (that's how they got to be towering) and you may also experience noticable wind shears.
Do note you don't need an anvil for a Cb.
Common sense should tell you that it can rain from a small cumulus cloud. This makes it a Cb but if there is very little vertical extent then there is very little chance of the more serious phenomena usually associated with the term Cb.
If you can't ascertain the vertical extent then one should steer clear. As I always say, "Discretion is the better part of valour, and cowardice is the better part of discretion!"
When it starts to rain then you have the dissipating stage which is the stage where microbursts and the rest of the Pandora's Box is unleashed. You don't want to play in this playground.
Cumulus are bumpy but rarely worse than uncomfortable.
Towering cumulus are somwhat worse (that's how they got to be towering) and you may also experience noticable wind shears.
Do note you don't need an anvil for a Cb.
Common sense should tell you that it can rain from a small cumulus cloud. This makes it a Cb but if there is very little vertical extent then there is very little chance of the more serious phenomena usually associated with the term Cb.
If you can't ascertain the vertical extent then one should steer clear. As I always say, "Discretion is the better part of valour, and cowardice is the better part of discretion!"
Humus Motor
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I wish I hadn't said 'large' - more likely perhaps, but research has shown that microbursts can occur near any vigorous convective activity. Oh, and it's not just a phenomenon confined to the USA - the 'European microburst' is less well studied, or known - but it most definitely does exist.
I have absolutely no misunderstanding whatsover about what a Cb is thank you - and if you think microbursts are just associated with rain, may I suggest you look up references to 'dry microbursts'. Google's a good start.
You pays yer money and yer takes yer choice. I took my choice a long time ago, and I'm not going to either argue the point or willingly take that risk in an aeroplane. I've said my piece for what it's worth and I'll leave it to you to scrap over!
Good luck guys!
I have absolutely no misunderstanding whatsover about what a Cb is thank you - and if you think microbursts are just associated with rain, may I suggest you look up references to 'dry microbursts'. Google's a good start.
You pays yer money and yer takes yer choice. I took my choice a long time ago, and I'm not going to either argue the point or willingly take that risk in an aeroplane. I've said my piece for what it's worth and I'll leave it to you to scrap over!
Good luck guys!
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I wouldnt! If u follow the textbook exactly, it says that flying within 10k of CB is bad news. That has to cater for worst case scenario i guess, but with an advised 10k avoidance radius, flying right under one is just askin 4 trouble in my book.
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I believe that Earthmover has succintly put the problem of flying near/under CB's. There is no reason why anyone would want to in my view. The dangers on offer are extreme.
Steer clear of them. A CB has the power to overide all you command. There is no argument in favour.
Steer clear of them. A CB has the power to overide all you command. There is no argument in favour.
when?
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I had to help a pilot that got caught below several CBs in a PA28 a couple of years ago. Trying to find a route between the CBs as well as the mountains. (It's a bit of a pain when you face 2 foes Cumulunimbus and Cumulus Granitus.......
Judging from his voice, flying below CBs are not OK at all!!!!
Judging from his voice, flying below CBs are not OK at all!!!!
First, for those who haven't participated in the other thread, I think DFC has deliberately quoted IO540 out of context. You've taken what was originally a statement of conservatism (that IO540 would cancel a flight where CBs are forecast with bases below the MSA) and re-quoted it to make it look rash. That's very low.
For those of you who spin anecdotes about CBs and what they can do, and post pictures of mean looking CBs... you could equally post a picture of a man-eating tiger in answer to the question "do you pet cats?"
Convective cloud is a continuum from small fair-weather cumulus to the meanest supercell. Meteorologists differ on when cumulus becomes cumulonimbus, but the best definition I've seen is that a CB starts when the upper levels glaciate. Since convective precipitation is predominantly born of the Bergeron process, that means that most showers are CBs. If you've ever flown in a shower, you've flown under a CB.
For those of you who spin anecdotes about CBs and what they can do, and post pictures of mean looking CBs... you could equally post a picture of a man-eating tiger in answer to the question "do you pet cats?"
Convective cloud is a continuum from small fair-weather cumulus to the meanest supercell. Meteorologists differ on when cumulus becomes cumulonimbus, but the best definition I've seen is that a CB starts when the upper levels glaciate. Since convective precipitation is predominantly born of the Bergeron process, that means that most showers are CBs. If you've ever flown in a shower, you've flown under a CB.
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Another thing to bear in mind is that you find gliders under, and sometimes in, cumulus. Unless you get a nice planform view they can be difficult to spot AND, if you've got a fan on the front, you're the one who has to do the avoiding 
As for flying through the clouds it's worth being aware that gliders do occasionally take "cloud climbs". The ONLY requirement (apart from Rule 29) for a glider, in the UK, to comply with when flying in cloud is that "No glider shall enter cloud unless all its occupants are wearing parachutes and have been instructed in their use".
My own approach, when there are well separated Cu around is to avoid them (smooth ride and less chance of finding a gaggle of gliders) when I've got an engine. Of course, when I'm not converting money to noise, thats a completely different story
As for flying through the clouds it's worth being aware that gliders do occasionally take "cloud climbs". The ONLY requirement (apart from Rule 29) for a glider, in the UK, to comply with when flying in cloud is that "No glider shall enter cloud unless all its occupants are wearing parachutes and have been instructed in their use".
My own approach, when there are well separated Cu around is to avoid them (smooth ride and less chance of finding a gaggle of gliders) when I've got an engine. Of course, when I'm not converting money to noise, thats a completely different story
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Earthmover,
Sorry, I didn't mean it to sound like I was refering to you but I have been following the other threads mentioned.
Just pointing out that due to the range of size and extent of a Cb some statements (by others) can be interpreted as extremely over-cautious.
Cancelling an IFR flight due to forecast Cb's might be considered thus.
Sorry, I didn't mean it to sound like I was refering to you but I have been following the other threads mentioned.
Just pointing out that due to the range of size and extent of a Cb some statements (by others) can be interpreted as extremely over-cautious.
Cancelling an IFR flight due to forecast Cb's might be considered thus.
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The morning started early with a planned 8 am departure. A check of the TAFS indicated nothing untoward and the morning air was clear and the sky bright. There was bated anticipation among the young passengers (all three of them!) as this was the first part of the journey to Manston to meet up with friends to go and watch the open at St Georges. I expected an uneventful and relatively short flight.
As expected the air proved to be silky smooth and the aircraft settled down at around 3,500 feet I seem to remember. There was nothing much to do as it was to early to listen and spot the other traffic as most people were still not airborne and I was content to enjoy a lovely morning, watching the scenery pass by and listen to the chat between the passengers.
I suppose the scan of the instruments had become a bit lazy - that’s strange I thought something doesn’t feel quite right. Oh my goodness we appear to be descending quite rapidly. A more intense scan of the panel didn’t provide a solution. The rpm and manifold pressures were normal, but I had a distinct feeling the engine was losing power. An even more intense stare at the EGT and the oil pressure provided no more comfort that to confirm all was probably still well with Mr Lycoming horses up front. Time to work those horses a bit harder, but rather than full power arresting the descent, the rate of descent increased with the aircraft now at full pitch up and full power. Infact the ground was coming up to meet us quite quickly.
A quick glance over the left shoulder confirmed that a grass strip with which I was familiar was within reach. Rightly or wrongly I concluded if all else failed that would just have to do.
It was one of those occasions were at the time I distinctly remember convincing myself that I had run out of things to try and there wasn’t a great deal more to be done than see what happened next. I was still convinced that for some reason the engine was not producing much power.
At about the point I recall I was thinking it was time to make a right turn on to final to the by now rather inviting grass strip, the silky smooth descent was suddenly replaced by the most intense choppy turbulence. For those of you who have sailed, the best analogy is when you are driving a small boat through a very short chop. We were going uphill rather more quickly than expected!
The passengers had been oblivious to the events unfolding until now but the Gameboys temporarily came to rest by their sides and they developed that quizzical expression kids do before you drop from the top of Oblivion at Alton Towers.
The roller coaster seemed to last for an eternity rather as had the descent but in reality I suppose it was a few minutes or so. Almost as suddenly back came the silky smooth air of earlier. The journey continued uneventfully other than a quick call to London info to warn them of the rather unusual weather encounter.
Hindsight as always is a wonderful thing. I do recall by that point in the journey there was a high overcast but reasonably well broken. I don’t seem to remember there were an indications of build ups above. I do recall there was a relatively dark looking isolated storm cell well away to the south - I would have guessed at least 30 miles away. There was some high ground to the north, but I use high in a very relative sense, the downs north of the Weald I don’t suppose are more than a few hundreds of feet high.
I don’t know to this day exactly what caused the phenomena but clearly there was a very intense down draught proceed by a funnel of turbulent rising air. It sounds very similar to what other people have described around thunderstorms and large Cbs.
I do know that the down draught was way outside the performance capability of the aircraft. Had I had time to be scarred I would have been!
Sorry to bore you all with the story but I know had I read a similar account I might have woken up at that time to what was going on - not than I am sure I could have done a great deal more about it. However it does emphasise the comments made here that the type of down draughts associated with Cbs are best avoided.
I still think as ever with any weather phenomena as other have said there are occasions when the sky is lightly peppered with very small fair weather clouds that are technically very immature Cbs. I would not expect this type of phenomena to be associated with those conditions but I could well be wrong?
Finally I recall a trip to North Weald for what was the annual trade fair. Come going home time there was a very large storm cell off to the West. I was absolutely amazed at the number of pilots who departed towards the storm cell. IMHO opinion it was madness. Sure enough 15 minutes later there was torrential rain and hail. What were they doing?
As expected the air proved to be silky smooth and the aircraft settled down at around 3,500 feet I seem to remember. There was nothing much to do as it was to early to listen and spot the other traffic as most people were still not airborne and I was content to enjoy a lovely morning, watching the scenery pass by and listen to the chat between the passengers.
I suppose the scan of the instruments had become a bit lazy - that’s strange I thought something doesn’t feel quite right. Oh my goodness we appear to be descending quite rapidly. A more intense scan of the panel didn’t provide a solution. The rpm and manifold pressures were normal, but I had a distinct feeling the engine was losing power. An even more intense stare at the EGT and the oil pressure provided no more comfort that to confirm all was probably still well with Mr Lycoming horses up front. Time to work those horses a bit harder, but rather than full power arresting the descent, the rate of descent increased with the aircraft now at full pitch up and full power. Infact the ground was coming up to meet us quite quickly.
A quick glance over the left shoulder confirmed that a grass strip with which I was familiar was within reach. Rightly or wrongly I concluded if all else failed that would just have to do.
It was one of those occasions were at the time I distinctly remember convincing myself that I had run out of things to try and there wasn’t a great deal more to be done than see what happened next. I was still convinced that for some reason the engine was not producing much power.
At about the point I recall I was thinking it was time to make a right turn on to final to the by now rather inviting grass strip, the silky smooth descent was suddenly replaced by the most intense choppy turbulence. For those of you who have sailed, the best analogy is when you are driving a small boat through a very short chop. We were going uphill rather more quickly than expected!
The passengers had been oblivious to the events unfolding until now but the Gameboys temporarily came to rest by their sides and they developed that quizzical expression kids do before you drop from the top of Oblivion at Alton Towers.
The roller coaster seemed to last for an eternity rather as had the descent but in reality I suppose it was a few minutes or so. Almost as suddenly back came the silky smooth air of earlier. The journey continued uneventfully other than a quick call to London info to warn them of the rather unusual weather encounter.
Hindsight as always is a wonderful thing. I do recall by that point in the journey there was a high overcast but reasonably well broken. I don’t seem to remember there were an indications of build ups above. I do recall there was a relatively dark looking isolated storm cell well away to the south - I would have guessed at least 30 miles away. There was some high ground to the north, but I use high in a very relative sense, the downs north of the Weald I don’t suppose are more than a few hundreds of feet high.
I don’t know to this day exactly what caused the phenomena but clearly there was a very intense down draught proceed by a funnel of turbulent rising air. It sounds very similar to what other people have described around thunderstorms and large Cbs.
I do know that the down draught was way outside the performance capability of the aircraft. Had I had time to be scarred I would have been!
Sorry to bore you all with the story but I know had I read a similar account I might have woken up at that time to what was going on - not than I am sure I could have done a great deal more about it. However it does emphasise the comments made here that the type of down draughts associated with Cbs are best avoided.
I still think as ever with any weather phenomena as other have said there are occasions when the sky is lightly peppered with very small fair weather clouds that are technically very immature Cbs. I would not expect this type of phenomena to be associated with those conditions but I could well be wrong?
Finally I recall a trip to North Weald for what was the annual trade fair. Come going home time there was a very large storm cell off to the West. I was absolutely amazed at the number of pilots who departed towards the storm cell. IMHO opinion it was madness. Sure enough 15 minutes later there was torrential rain and hail. What were they doing?
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Depends what you mean by OK.
Last summer, after a memorable trip round the Orkneys and Outer Hebrides, I flew back to London IFR through some generally mucky weather that turned out to have embedded CBs.
I survived just fine.
But it was extremely bumpy, the rain was so heavy it was coming in through the canopy seals, I scared myself and my pilot passenger ****less, we witnessed a lightning strike that was too close for comfort and the paint job on by aeroplane was slightly damaged.
So it was not OK and I won't be deliberately doing it again. If Cbs are forecase, I now specifically ask any radar service for information on the storm cells. But if I find myself in that situation again, I will know it will probably not kill me.
Last summer, after a memorable trip round the Orkneys and Outer Hebrides, I flew back to London IFR through some generally mucky weather that turned out to have embedded CBs.
I survived just fine.
But it was extremely bumpy, the rain was so heavy it was coming in through the canopy seals, I scared myself and my pilot passenger ****less, we witnessed a lightning strike that was too close for comfort and the paint job on by aeroplane was slightly damaged.
So it was not OK and I won't be deliberately doing it again. If Cbs are forecase, I now specifically ask any radar service for information on the storm cells. But if I find myself in that situation again, I will know it will probably not kill me.
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As for flying through the clouds it's worth being aware that gliders do occasionally take "cloud climbs". The ONLY requirement (apart from Rule 29) for a glider, in the UK, to comply with when flying in cloud is that "No glider shall enter cloud unless all its occupants are wearing parachutes and have been instructed in their use"
A bit worrying though - what do they do to keep separation from other gliders? Are they just trusting to luck??
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CB's are not fun to fly through. A year or so ago Ludwig and I flew to Guernsey. The trip ended up with a vectored ILS through a thunderstorm, black as night and the airframe sounded like it was being shotblasted!
We would go from 1000ft sink to a 1000ft climb in seconds. Made coming down the glideslope hard work, I have never been so happy to see the runways lights appear in the rain.
I prefer to steer clear as the ride is not the most pleasant. But I dont see the need to cancel a flight when cb's are forecast on a 9999 day. I just take extra care to keep clear. Embedded is a different story.
We would go from 1000ft sink to a 1000ft climb in seconds. Made coming down the glideslope hard work, I have never been so happy to see the runways lights appear in the rain.
I prefer to steer clear as the ride is not the most pleasant. But I dont see the need to cancel a flight when cb's are forecast on a 9999 day. I just take extra care to keep clear. Embedded is a different story.