IFR through Towering Cumbulus

[crxcte]

I know as a pilot we don't fly through towering cumulus clouds.  But, when the clouds are small what is the limit on the height?  I will fly through a towering cumulus cloud when less than 8,000 MSL.  Sometimes its a little bumpy but never bad. 

What is the limit to fly through a towering cumulus?  We never know what the updraft winds are on these things are.

 

[flight2000]

My personal limit is to avoid anything larger than 3,000 feet in height unless it's just a straight overcast layer.  The cumulus clouds around Kansas are normally easy enough to fly around and not through.  ATC hasn't given me any issues with deviation around the big stuff.  YMMV.

Brian

[FlyDave]

The energy in any cumulus cloud can be quite significant. I think even with 3,000' of vertical developement the turbulence can be severe.

In my glider at 17,500' I've hit 1000+ fpm up just 400' below cloud base with the variometer (VSI in a glider) indicating an increasing climb rate. I had to move quickly to the edge of the cloud with full spoilers and gear down so I would not get sucked up into the cloud. It can get pretty hairy below a cumulus cloud (Cu (queue) as we call them). There can also be a shear line between the rising air directly below the Cu and the descending air just outside the perimeter. This alone can bend an airplane depending on your speed. I haven't been inside a Cu but I'll bet its an E-ticket ride and not a fun IFR experience - not to mention dangerous!

I think it's best to avoid them ANY time you can, but this is just one of my "minimums".

[roundout]

I won't go through them. Usually it's easy enough to avoid them. If you're flying along in a solid layer where you can't determine the location of building clouds, well, you've already screwed the pooch. I know people do it, but it's simply asking for trouble. I have seen clouds build at several thousand feet per minute before, even in to the flight levels. Just a couple weeks ago I was swinging the gear in a King Air 200 and we had been watching some storms for about 150 miles and made a plan to get through them about 20 miles out based on what we saw with our eyes, the radar, and XM. By the time we flew the last 20 miles, the clouds had started developing rapidly and we had to totally amend our plan to avoid them. Keep in mind this is at nearly FL300. 

 

Conditions can just change too rapidly to fly through them. It's not worth it. Besides, you might spill coffee on the interior of your airplane. 

 

[FlyDave]

A couple of things that I forgot to add to my previous post that might ruin your day are:

• 
  
• Lightning
  
• Hail
  

[Ned Gravel]

MIke Elliot posted a four part series on IFR and Cumulus on the Aviating.com Mooney List at: http://lists.aviating.com/mailman/private/mooney/2010-July/038350.html.  It was written by Jay Ledbetter and is full of golden words of Wisdom.  

• 
  
• How can you tell if a cloud has hail in it from the outside?
  
• What is the difference between a black and a grey base of a cumulus cloud?
  

Good article.  Highly recommended.

[Jeff_S]

So, that would be an interesting article to read but it appears to be password protected. What's the secret to get in?

[Ned Gravel]

I received permission from the author to post it here. It is posted on the aviating dot com site for Mooney drivers in four (4) parts. I am going to put them all into this one post.  Wish me luck.   It opens with a comment from Mike Elliot:

Three days ago, a newly minted IFR student of mine emailed me, Michael
Baraz and a friend of his, Jay Ledbetter and asked us how the heck he
was supposed to hold altitude getting banged around like a ping pong
ball in cum. clouds. His training exposed him to some of that, but he
had his safety valve, me, sitting next to him so it never occured to
him to think that he may bust altitude, as I wouldnt let him let it
get that far out of bounds before I would tap on his altimeter or ask
him if he was decending to land etc. Now in real life, single pilot
IFR, he decided to ask the three of us this question. What resulted
was a terrific exchange between him, Michael, myself and Jay. Jays
response was so good,  Michael and I both encouraged him to develope
it further into an article.

Here is what Jay has come up with. I hope you enjoy it as much and
find it as valuable as I do.
----------------------------------------------------------------------------------

What I Wish Somebody Had Told Me
                     ---
Advice to New Instrument-Rated Pilots

By Jay Ledbetter                                             June, 2010

When we were learning to be Private Pilots, we all learned a little
about instrument flight…precious little.

I remember quite vividly, back in 1967 as a hopeful pilot-to-be, how
it all began.  My instructor was a retired Air Force bomber pilot, and
he taught me as he was taught.  A lowly Piper 140 was not worthy to
sit alongside a B-47, but he taught me to fly it as if it were the
same plane.  Almost every day, I would meet him in his cramped little
office at the little uncontrolled airport in Artesia, New Mexico. I
would plop down on the other side of his desk, dropping my little
logbook in front of me onto the top of the old olive-drab WWII office
desk, and  smile.  He would smile back, and offer a greeting and his
big hand.  He was a great guy.

We began the lesson, as we did each time, with a short “here is what
we are going to do today” session.  His eyes sparkled, and his quick
smile changed the pattern of the freckles on his cheeks as on this day
he described in lofty terms the intricacies of instrument flight.  To
him, he was describing an intimate relationship that he had cultivated
over the years, as if he were lovingly polishing an antique car he had
personally restored.  From my side of the desk, he might as well have
been describing the precise method by which one fastens the
left-handed fribberjabit onto the frenambulator assembly.  I paid
attention, and I tried to visualize what he was saying, but sadly… I
didn’t get it.  No pilot ever does, until you do it.  I guess that is
why the FAA forces you to actually fly the plane with reference to
instruments alone.  You can’t study your way to proficiency with
regards to learning instrument flight.

“Ready to go?” he asked (it was his usual question, and a signal that
the talk-through session was at an end) as he stood from the old
swivel chair that had been rescued from an Army-Navy store in town.  I
never answered.  I was still trying to visualize the bolt that held
the fribberjabit in place.  It didn’t matter, though, because he was
already well past me, on the way to the door. An affirmative answer on
my part was assumed.  For me, the concept of being “ready”, was a
somewhat fluid concept.  It occupied a wide range of conditions from
“are you kidding?” to “sure, let’s go do this.”  Today I was somewhere
closer to the left side of the scale.  Either way, we were headed out
the door, and it would be unspeakably awkward for me not to follow.
As he passed the filing cabinet in the corner of the office, he
snatched off its top a large bulky white plastic bent thingy that I
had not noticed before.

I wondered what he might be planning to do with that weird device.  It
lacked a long handle, so would not serve well to scoop out any
significant volume of the candy wrappers that were accumulating to an
alarming depth in the rear footwell of the little Piper.  He ate a lot
of candy.  He told me it settled his nerves.  Today, his pockets
bulged with a bit more than his normal supply.

After the preflight, he kept the curious device in his lap through
start-up and taxi.  After a careful analysis of its design and
position, I concluded that he intended to use this device as a shield
to protect his nether regions from further damage by some of the
debris that would circulate around the cabin in truncated arcs as I
practiced stall recoveries.  One of the most important things I
learned about stall recoveries is that if you push the yoke forward
quickly enough at the beginning of a stall, you can enter that zero-G
or even negative-G zone where all the loose things (both light and
heavy) in the cabin arrange themselves randomly on the ceiling, and
then fall back briskly into new and exciting locations as you pull the
yoke back again to bring the plane into the 1+ G range.

Stall recoveries scared me… and despite all his training and combat
missions flown over enemy territory, my stall recoveries also scared
him.  Sometimes one or both of us would involuntarily let a bad word
escape to join the rubble which was moving up and down in the cabin
generally tracing in the air the letter “M”.  I would still be flying
the plane, though - not because I had great aviation skills, but more
as the result of physiological factors. With that degree of terror it
is simply impossible to let go of the controls.  When your hands are
on the controls, you are the pilot, like it or not.

We took off, and headed to the practice area (which generally occupied
most of the south-eastern corner of New Mexico).  After he finished
sweeping a number of displaced candy wrappers off the top of the glare
shield with his hand, he handed me the strange device and said “I’ve
got the airplane.  Put this on.”  I thought this act expressed the
greatest level of self-sacrifice I had ever witnessed to date.  No
wonder he was a military hero.   Deep emotions welled up, and I have
to admit that I teared-up just a little as I placed the device in my
own lap.  Its light weight still was still sufficient to remind me how
tender my bruised lap was from repeatedly testing the upward limits of
the seat belt system in previous days.  I would be protected from
injury and he would leave himself exposed.  What a guy.

“No, you put it on your head.” He instructed.  The look on my face
must have been as effective as a radio transmission in telling him
what I was thinking.  I was weighing the relative values of my brain,
and my… when he quickly snatched the device from its resting place and
after adjusting a head strap, placed it firmly on my head.  He
adjusted the white plastic shield into a position where it took the
position of a grossly outsized baseball cap’s visor.  Two things
occurred to me, somewhat simultaneously, at this time.  First of all,
I couldn’t see outside the plane.  Secondly, since he was adjusting
this device onto my head with both hands, nobody was flying the plane.
 Both of those realities left me in a panic as I said, “I really can’t
see, now.”   “Good.” He responded, “Now, fly the plane using what you
can see.”   For the next few lessons, I did what you, and every other
new pilot, has done.  But I will bet you got to use those new-fangled
foggles.  What an improvement those are.  They hardly hurt at all when
they fall off the ceiling.

Our vision thus encumbered, we all learned to fly rudimentary
maneuvers solely on the instruments we saw before us on the panel.  Up
to that point I thought that an “unusual attitude” was when Granddad
interrupted with laughter the most tearful moment of a Gretta Garbo
movie.  As part of our private pilot instrument training, we all
learned that when our bodies are lying to us, the instruments are
telling us the truth.  We learned to do an immediate course reversal
and immediately get out of inadvertent flight into instrument
meteorological conditions.

But at some point, we have all wanted to take the next step – to get
an instrument rating to open up for us far greater flying
environments. Then, we spent hours and hours looking at nothing but
the instruments.  We found ourselves flying intentionally into IMC
conditions, and learning to see the insides of clouds (which don’t
give very much attitude information), and watch little streaks of
condensation form on our windscreens.  It was all so new… and so
scary.  But it was the threshold of another level of flying skill.
Soon, our visual flight was limited to taking off, and that last
minute or two on final approach as we reached the decision altitude.
We learned that on occasion the instruments can lie to us, and you
have to do a type of lie-detector exercise to see which one it is.
Then you have to identify the lying instrument for what it is, and
block it from view (lest you inadvertently rely on it).

I remember the day I finally got my instrument ticket, and was able to
get my head “out of the cockpit” once again.  It was surreal.  I could
see!  I had to learn how to fly visually all over again, and how to
balance that with instrument-only flight as the flight conditions
changed.

I am sure you experienced much of what I did, with varying degrees of
bad words released into the air.  But the end result was always the
same… an instrument rating, with or without a trashcan full of candy
wrappers.

Instructors, especially instrument instructors, have huge volumes of
information inside their heads.  They try to cram inside our heads
sufficient information to prepare us for the three phases of our
instrument exams – the written, the oral, and finally the practical
flying phase.  They do a great job in helping us get past those
hurdles, which appear as snowcapped mountains on our horizons as we
begin the daunting task of obtaining our instrument rating.  Then that
magical day arrives and we finally convince the examiner that we are
worthy of his blessing.  A few keystrokes in the computer, and we are
now “certified”.

We, as newly-rated instrument pilots learn much more than the “basics”
needed to pass the exams, but the sad truth is that most of us who
finally have earned that coveted rating don’t spend the next fifty
hours flying with our instructors – so we can progress from the
“masters” level to the “doctorate” level of instrument flying.  That
is probably because we, as students, are reluctant to keep paying for
further flying lessons.  But I am fairly sure that the instructors are
equally happy to have a break, so they can take some quiet time to get
their hands to stop trembling once again. After a few group therapy
sessions, they will be ready for their next student.  A new
instrument-rated pilot needs to progress quickly past the entry level
of instrument flight, because if we don’t progress to the next levels
we risk not only our lives but the lives of those trusting souls who
ride along with us into the blue… or worse, into the gray.

It is my position that when you first put your new license into your
wallet, with that coveted “Instrument” word imprinted on the back, you
are finally ready to really learn.  I call an “instrument ticket” a
“learner’s permit”.

An instrument rating is a statement by your instructor, ratified by
the FAA’s designated pilot examiner,  that you have progressed to the
threshold level of competence to allow you to fly in instrument
meteorological conditions (when current).  Becoming proficient at a
level to allow you to be truly safe, is at a yet higher level.  Get to
that competence level, and do it with purpose.

So, you now have an instrument ticket, and are flying on IFR flight
plans and occasionally encounter IMC.  Great.  Now you are getting
some real experience!  That empty right seat serves as a constant
reminder that you are the PIC, and that you are in charge of all the
decisions – both good and bad – that will shape every flight.

I have learned a lot since I began single-pilot IFR flying.  I have
learned a lot of it the hard way.  I am writing this to you, in order
to give you a few lessons I wish someone had given me, early on.  You
have some skills, and are demonstrably competent in IFR flight.  But
maybe a few pointers I will give you now will find their way into your
bag of tricks, and might save you some trouble later on.  I wish
someone had written this information for me when I was in your place.
So, I will do this for you.  Someday, you might consider doing this
for someone else.

You may grow to love the IFR flight environment as much as I do.  I
never fly VFR unless on a short currency flight, check-outs, or taking
people sightseeing and such.  I suspect you now are really
appreciating the safety and security of IFR flight.  But with that IFR
ticket comes another challenge... flying IFR also allows you to get
yourself into much more dangerous situations much more quickly.
Recognizing those before they envelope you, and avoiding them, is the
key.

Let's talk about clouds, and turbulence.  And let's talk about some of
the finer points of IFR flight involving clouds and such.

Turbulence, especially in IMC, will focus your instrument scan like a
laser.  Stay on top of it, but don't be too aggressive.  Gradually
correct for altitude excursions, because updrafts are almost always
coupled with downdrafts, which net closer to zero.  When everything
settles down, take stock of where you have gone, and get back to where
you need to be... gently.  If you are in moderate turbulence, where
control of the aircraft is somewhat "iffy", then do tell the
controller.

As far as getting IFR approaches, don't expect a lot during the summer
time of year. Every year I must fly with a safety pilot to stay
current.  Normally I get a lot of approaches, but I don't get any
holds.  Keep track on your personal calendar and in your logbook of
your currency.  Calendar your next currency expiration date, and plan
some currency flights before you expire.  There is always an
instrument-rated pilot out there who has the same problem as you do,
and who will be happy to fly as the safety pilot with you, as you will
with him.  If not, then call your instructor and ask him to give you
some additional training which will culminate in currency.  By that
time his bad dreams will have diminished, and his hands steadied.  He
will be happy again to fly with you.  Instructors are smart, but all
have short memories.

Put your instructor’s phone number in your phone.  I have called my
instructor from all over the country, to help me think-through
situations, and help my decision-making when I lacked confidence.  It
is much better to call your instructor to confirm a good decision you
have considered than to avoid making the call that could save you from
a bad decision.  With an abundance of counsel, there is wisdom.

I love cloud flying.  As you well know, clouds are different from one
another.  Stratus (stable air) clouds create huge areas of poor
visibility (hence IFR), but little or no turbulence.  You will see a
lot of that in the fall and winter. There can be little puffy cumulous
(cotton balls) and those don't really count.  But most cumulous
(unstable air) clouds are generally isolated from one another (unless
they are combining into a squall), and have clear skies between.  The
warmer weather of late spring and summer brings this type of cumulous
clouds.  Cumulous clouds are full of bumps (and bruises) because they
are developing vertically.  The interior segments of cumulous clouds
are always churning, hence lots of turbulence.  Some of that
turbulence will be reminiscent of some of my more spectacular stall
recoveries.

All developing cumulous clouds have a flat bottom.  That bottom
represents the level at which the updrafts from below hit a level
where the moisture becomes visible. That is the dewpoint level.  You
can use that level as a very general guide regarding where you will
find calmer air.  For reasons I do not fully understand, when you fly
into the airmass above the bottoms of cumulous clouds, the air is
smoother.  So, they give you a little-smoother-altitude guide in the
sky.  Flying below vertically developing cumulous formations will be
bumpy too.  Remember that there is as much air movement going on below
the dewpoint level as there is above it.  Gliders get under developing
cumulous clouds to take advantage of the updrafts and gain altitude. I
have seen a parachutist become caught in a cumulous cloud updraft and
carried higher and higher - even though he desperately wanted to get
to the ground.

If you see a rain shaft coming from the bottom of a generous cumulous
cloud, you might want to avoid it to the degree you can. If you can
see through the rain shaft easily (not heavy rain), then use caution
if you need to fly through it.  If you can't see through it - avoid it
altogether.   Rain is an air pump, and creates some amazing
downdrafts.   Besides, rain and lightning often are seen together.

Rain is not always your enemy.  You can land in the rain, and I have
done it a bunch of times.  The rain that comes from stratus clouds is
widespread and gentle.  But some rain can be very dangerous.

Cumulous clouds, in their dissipation stage, form concentrated rain
shafts.  Avoid landing through a heavy rain shaft.  Remember that the
air that is swept downward in that shaft must go somewhere.  Envision
pouring water on the porch.  The water hits the porch, then it jets
out very fast to all sides.  That is what the air does too. When it
hits the ground, it spreads out in all directions.  Have you ever been
near a rain shaft and felt a rush of cold air from its direction?
That is called a "gust front" by the non-pilots.  Pilots know that is
an indication of some amazing low-level wind shear, and its effect on
flying aircraft can be deadly.

As you fly an approach toward a rain shaft near the ground, you may
see a quick spike in airspeed, followed by a decrease in groundspeed.
You have just flown into the gust front.  The plane actually flies a
little better, if slower.  The tendency is to reduce power to continue
the decent.  That will play into the problem, later. Then you enter
the part of the downdraft that is pretty vertical.  Now you need to
apply a lot of power and some nose-up pitch to maintain altitude.  You
might lose a little airspeed as you do so. That multiplies the danger.
 What comes next is what can kill you.  As you fly to the other side
of the downdraft, the direction of the wind switches to behind you.
Your airspeed drops dramatically, and if you are at Vso+10, you just
might stall... with no chance to recover before you plant it in the
field.  That is precisely what happened when Delta Air Lines flight
191 flew into such conditions on the afternoon of August 2, 1985,
while on final approach to KDFW.  Miraculously, three of eleven
aircrew survived, as did twenty-six of one hundred fifty-two
passengers.  We all learned a hard lesson that day.  This event led to
a number of improvements in the sensor arrays around major airports,
and some helpful safety briefings.  But the sad truth is that pilots
still kill themselves, and others, by ignoring these lessons.

If you must penetrate a rain shaft of any density at pattern altitude
or lower, remember to carry some extra speed to compensate for these
effects.  I would suggest you break-off an approach if you must pass
through a rain shaft that you cannot see through.  I remember clearly
one night landing some years ago, when I was carrying passengers back
from Montana to Denver Centennial.  We had been in IMC almost the
entire trip, and we were in and out of snow and rain storms as we
decended into the Denver class B.  The ATIS told me that at
Centennial, there was rain in the vicinity, but current visibility was
three miles and the ceiling was better than a thousand feet. It was
the culmination of hours of high-intensity flying, and as I was being
vectored for the ILS 35R approach, the city lights illuminated the
flat bottom of a dark cloud over the approach end to 35R.  A rain
shaft decended from the base of the cloud directly across my approach
path.  I turned to final at the FAF (CASI), dropped the gear and
flaps, and adjusted the propeller and manifold pressure to the right
“numbers” for a ninety-knot decent.  I kept my eye on the rain shaft
and the runway lights.  I could always see the lights through the
rain, and so continued.  By the time I got halfway to the runway, the
rain shaft had dissipated, and moved off to the west of the flight
path.  So, I continued the approach.  The landing was uneventful, but
I kept my hand on the throttle and carried a little extra speed just
to be certain that there was no wind shear coming off the shaft that
might affect the safety of the flight.  I was on high alert.  These
are things you learn by experience… or from stories like these from an
old pilot.

Cumulous clouds with a grey bottom are ok.  They have some turbulence,
but it is generally not bad. If you have the choice, the upper levels
of the smaller cumulous clouds are generally safer and smoother than
the lower levels.  If the cloud has a black bottom, that means it is
pretty large, and is developing pretty mean guts.  You can still fly
shallowly through the edges (with great caution), but I do what I can
to avoid those. Turbulence can extend away from the edge of the cloud
in some of the larger ones.  If you see rain coming from the bottom,
then that is a sign that there will be really bad stuff going on
inside.   The rain-induced air pump extends to some altitude within
the cloud.

If you eyeball-estimate the cumulous cloud ahead is more than a
half-mile across, then begin to use higher caution.  Those are getting
big enough to have some heavy turbulence inside.  If it is more than a
mile across, and has a black bottom, then I would suggest you find a
way around it.  When they are this big, they get dangerous.  Remember
that flying just under such a cloud is not much safer than flying
through it.  Remember, there is no cumulous cloud that does not carry
with it some turbulence.  The rule of thumb is that the bigger the
cloud, the more severe the turbulence.

Some of the very big cumulous clouds have a green cast to the
underside.  If you see that, stay well away.  That color always means
hail. It can also mean incipient tornado development.  Hail is lifted
high into the cloud by the most amazing updrafts.  An updraft that can
lift a ball of ice, can lift your airplane like a leaf.  Hail
sometimes works its way high enough to be swept to the side of the
cloud by upper level winds, and then it falls free of the cloud at
distances up to twenty miles from the cloud column itself.  Be
particularly wary under the "anvil", because this is the way the upper
level winds are blowing from the storm, and hail can be present (and
invisible) in this area.

You can encounter some surprise icing in cumulous clouds.  Remember
that the interior of clouds is substantially cooler than the air
temperature elsewhere.  As you fly toward, and then into, a cloud, you
can open the vent and use the back of your hand within the wind stream
inside the cabin to see what I mean. It is an amazing change in
temperature.

Rain can be lifted very high inside the cloud to the colder areas of
the atmosphere, cooled almost to freezing, and then fall back through
the cloud to impact your airplane without gaining much warming in the
descent.  When you fly through some of the larger cumulous clouds, be
watching for icing as well.  I always turn on my pitot heat before
penetrating any cloud at any altitude.  I turn on the other anti-icing
equipment before penetrating clouds when I see the OAT outside the
clouds is within ten degrees of freezing.  If you do pick up a little
ice inside cumulous clouds, on the other side of the cloud as you
enter warmer air, it will usually sublimate away.

One of the most deadly conditions for pilots (especially those without
weather radar info in the cockpit) is embedded thunderstorms.  When
there is widespread stratus, limiting visibility, then a few areas of
vertical development can begin, and those can build into some pretty
serious storms - all hidden from view by those nice gentle stratus
clouds.  The transition from smooth stratus clouds to developing
cumulous clouds is gradual, and can be initially unnoticed until it is
too late to avoid them.   If you have a strike-finder, you can find
those well-developed thunderstorms in the system, or you can use your
ADF (set to a frequency not coinciding with a station) as a guide.
With the ADF tuned, you will hear the pop and sizzle of the strike in
the speaker, and the needle will point to the strike.  If you can
afford one of the new Garmin GPS systems which supports XM weather,
you might want to get one and use it for weather awareness.  The
images are only a few minutes old, but give you very good information
on what is going on ahead.  They are expensive, but when compared to
your life, they are cheap.  In planes without XM weather or weather
radar, I try to get above all the stratus layers, so I can see the
pop-ups and avoid them if I need to.  You can even see the cumulous
developments from between layers.  I have been able to do that as
well.  Don’t be lulled into a false sense of security because the
clouds you are in are smooth, and you don’t see any developing storms.
 What you don’t know can hurt you.

If you are in turbulence that is so robust that you can't hold
altitude within a couple of hundred feet, then call the controller and
tell them what is going on.  You may wish to ask for a “block
altitude” clearance.  Even if they don't give you a block clearance,
just knowing that you are having difficulty will often help them give
you a modicum of grace on the altitude issue.  Putting that particular
information "on the record" by a radio call can also avoid them
busting you officially on the altitude issue.

Another important thing to remember in turbulence is to keep your
wings level. I am aware of a Saratoga which lost a wing entirely
(exceeded structural limits on airframe) by flying into a
thunderstorm.  He went into the storm with two, and came out with one
on... and one off.  The postmortem on the accident was published, and
the consensus was that the pilot tried to correct for a strong updraft
by pointing the nose at the ground and wound up exceeding Vne trying
to stay at assigned altitude.  The "book answer" is to keep your wings
level, and accept altitude excursions.  The book is right.  Again,
notify ATC when you are doing that, so they can understand what is
going on with the reading on their screen.  If it gets too bad, don't
hesitate to ask for an immediate course reversal and get out of there.
 It's often better to go back to where you know the plane is flying
well, than to take chances on what lies ahead.

Finding out where the cloud tops are is great.  PIREPS are helpful, so
look at those on DUATS or ADDS.  You can find some information on tops
in the first paragraphs of the DUATS briefing.  But tops are only
useful for stratus layers.  You will be unlikely to be able to get
over any significant vertically-developing cumulous in a plane that is
not turbocharged.  When I can, I usually do get above all the clouds I
can.   At least I want to find a clear place between levels in stratus
formations.  With towering cumulous formations, they normally have
some clear air space between them, and you can weave a little left and
right between them without asking for clearance to do so.  Just don't
stray more than a quarter-mile or so from your flight-planned path.
You might talk to the controller to tell him what you are doing, so he
doesn't get confused by your weaving flight path across his scope.

Maybe the best thing about IFR flight is that the good ATC guys will
happily steer you around storms.  It happens a couple of ways.  First
of all, remember that their new displays only give them Nexrad stuff.
They don't get to see every cloud.  Unless there is enough moving
moisture in the cloud to generate a return signal, they can't see it.
Also, some significant turbulence associated with moist air (not a
cloud) is enough to create a green display as well.  So, they have
better, but limited, information on precipitation on their screens.  A
good controller will identify trouble ahead (maybe that you can't
see), and suggest a route around it for you.  You can take his advice,
or if you can see better than he can what is ahead, you can suggest
your own routing.  They will generally approve your routing - since
they know that you are the PIC, and supposedly have better visual info
than they do.  Or, if you see a buildup ahead, you can start doing
some planning yourself.  You can sometimes see which way the whole
system is moving, and fly behind it.  You can sometimes outrun the
system by flying ahead of it.   It is very common for pilots to
request a course deviation to get around a buildup.  You can do that
by calling ATC and saying something like this sample radio traffic,
"Denver Center, 56Echo, request course deviation twenty degrees to the
south to avoid buildup ahead".  The response is normally, "56Echo,
deviation approved. Notify when back on course direct Centennial".
When you have cleared the buildup, you can jink back to your original
course, and then call ATC to tell them you are back to direct
Centennial.  This brings me to my next point... fuel.

IFR flight over any reasonable distances rarely goes the way you plan
it.  I know the regulations about carrying enough fuel to make your
destination plus forty-five minutes.  I think that is much too
aggressive.  You can just bet on some ATC reroutings, forced altitude
changes, and jinking around buildups in most every flight. The ATC's
plan, rather than your plan, is what will prevail.

I really hate to fly into that last hour of fuel.  When I get a
significant forced rerouting by ATC which extends my distances, I
already begin looking for a place short of my destination with fuel
where I can set her down.  On one of my normal routes (between Denver
Centennial and Durango) it is not uncommon for me to file for a more
direct northern route, and wind up getting cleared for a dog-legged
southern one, or visa versa. These routes are separated by half the
state, and make thirty minutes difference in flying time. I have tried
over and over to anticipate what they are going to do, to no avail.  I
think they must sit around at clearance, and say "How can we mess with
Ledbetter today?"  So, remember that extra fuel is your friend...
unless you are on fire.

Remember that HIWAS and other weather information is still available
to you during IFR flight.  If you have a second radio, you can tune in
the information, and listen to both radios so you don’t miss some
information, or a call.  Sometimes I call Flight Watch to see what
they are showing.  You do that by telling the controller that you wish
to leave the frequency in order to pick up weather information.
Unless they are getting ready to hand you off to another controller,
they will normally allow you to do that, and will instruct you to
check-in with them within a few minutes.  There is still not much
cross-talk between the controllers and the weather guys.  That is a
problem without an easy solution.  I find myself a quiet segment on my
trips, and use those to take advantage of the weather briefings I can
get from the other sources.

Take advantage of other pilots ahead of you.  As you talk to ATC, you
may  hear chatter with other planes of similar type ahead of you.
They can give you lots of information.  If you are experiencing some
turbulence, or worried about icing, or such, you can ask ATC to
inquire of the pilot ahead what is going on at his altitude and
location.  You will hear the report first-hand, or ATC will relay.  I
had one flight coming back to Centennial from Roswell (entirely in the
clouds), where I had a Bonanza about 40 miles ahead of me on the same
routing.  I was often clear of clouds (barely), but my routing kept me
mostly in a near-solid cloud bank where I had no real visibility to
the side or above or below.  I was picking up a trace of ice on
occasion, and wanted to know whether I had a chance of breaking out of
the clouds, or whether a change in altitude would make any difference.
It looked to me that the clouds were closing in tighter, ahead.   I
did what I just suggested you do, and found out that he had just
broken out of the clouds into clear skies forty miles ahead.  I was
able to relax, and follow him into the blue.

As you know, airliners give regular ride reports.  On occasion, ATC
will want to know what your ride is as well.  You can ask for ride
reports ahead at your altitude as well, and other pilots will gladly
report.  Sometimes a change in altitude will make all the difference
in the ride.

You have probably already seen the layering effect of air.  If you are
in a lower airmass, and pass into a higher one, there will often be
indicators of passage.  Higher moisture in the lower layer - showing
up as haze - will be a sign.  Often, air masses don't move together,
and the boundary between them is characterized by continuous
turbulence (light chop, normally).  Moving up a thousand feet will
often get you out of the boundary chop layer.  You can encounter these
layers in solid IFR as well, so even though you think you are
encountering turbulence solely based on clouds, you may be only
experiencing turbulence at a boundary layer.  ATC is normally happy to
give you changes in altitude to avoid turbulence.  You can ask for it,
and the worst they will do is to refuse you until traffic clears, then
they will grant your request.  I did find myself in IMC coming back to
Centennial from Sheridan, Wyoming one afternoon.  I was given a
westerly routing (again, not what I filed for).  I climbed to get on
top of a thick cloud layer, and was running just above the tops.  It
was beautiful, and a neat place to watch the sunset.  But the cloud
tops kept getting higher.  I would ask for higher altitudes, a
thousand feet at a time, as I flew south, to stay above them.
Finally, I was reaching the point where the plane really didn’t want
to fly well anymore (it was not turbocharged), and I was finding
myself in the clouds more than out of them.  I could see blue sky
above, but couldn’t get to it. I also could get occasional glimpses of
the cloud bottoms below, only a couple of thousand feet below.  I was
starting to pick up a little frost on the front of the wings.  It was
nothing that affected the flight of the aircraft, but it was not
something I wanted to see continue.  I determined to ask for lower.  I
got on the radio to Center and told them I was picking up some ice,
and wished to have lower.  I told them the target altitude I wanted.
Center told me that my request was denied, because that altitude put
me below the MEA at that location.  I was over the mountains west of
Cheyenne.  The controller did give me a glimmer of hope. He told me
that in a few miles he would pass me to Denver Center, and they would
have the authority to give me lower.

Immediately upon checking in with Denver Center, I asked for lower.  I
got it.  Problem averted.  The bottom line is that controllers don’t
sometimes care if you are picking up ice.  They figure you put
yourself where you are (regardless of whether that is true or not),
and if you are picking up ice that’s your problem.  Then they lean
back in their padded chair and take another sip of coffee from a mug
that has “Air Traffic Controllers are gods” written on the side.
Remember the old saying:  “When the pilot makes a mistake, the pilot
dies.  When ATC makes a mistake, the pilot dies.”  If you must, argue
with them.  I have done it, and finally embarrassed a controller into
giving me what I needed at the time.  Occasionally, the squeaky pilot
gets the amended clearance.

But there is some silver lining in that cloud of controllers.  I have
encountered a spectacularly helpful controller at Denver Center on the
way back from Grand Junction one day.  The MEA for my first leg of
routing was 160.  There was ice forecast at just higher than 170, all
the way up to FL230.  The bases of the clouds enroute (for half of the
trip) was 16.8.  I was flying eastward, so had to file for 170.  I
have seen icing forecasts be wrong (both in my favor, and against me),
but just how to deal with the uncertainly in the system is something
that comes only with a lot of IFR experience. Don’t push it at this
stage in your flying.   Anyway, back to the story.  After being handed
off to Center, the controller told me to climb and maintain 16.3.  I
had never previously gotten a clearance to other than an altitude that
was one of the cardinal thousand feet levels.  This
flight-level-and-a-piece clearance put me between layers in clear
skies, and ice-free. The controller had been paying attention to the
pilots who were flying that route.  He heard lots of reports of
bottoms on the clouds, and was kind enough to keep me below them for
the first leg of the trip. By the time I had to go to FL180 later in
the trip to reach a higher MEA, I could punch through some thin layers
and get back on top for the last leg across the front range. Without a
very sensitive controller, thinking as a pilot, I might have had to
fly at 170 initially, may have encountered sufficient ice to force me
to turn around, and have wasted time and fuel on a futile trip.  I
hope you get lots of these kinds of guys. They are out there.

If you know you have a pilot in a similar aircraft behind you on a
similar routing, be courteous and give ride and weather conditions
reports to the controllers.  The guys behind you will appreciate the
info.  I recall flying southward along the front range to Roswell, and
was listening to radio traffic between Center and a light aircraft
which was on flight following.  The pilot was near Pueblo, some fifty
miles to the north of my position, and was trying to cross the
mountains to the west and stay out of mountain obscuration.  The
mountains were pretty well socked-in all along the front range of
Colorado.  He had some silly desire not to encounter cumulo-granite as
he passed to the west.  The pilot was asking the controller if there
was any clearing in the clouds (the bases of which were just below the
peaks along the front range).  Of course, I knew that the controller
was unlikely to have that information.  But I did have it.  I got on
the radio and volunteered some real-time information from my position.
 I told the controller that I saw no breaks from Denver south, but the
cloud bases were lifting dramatically south of Raton, New Mexico, and
it appeared that the VFR traffic could stay under the clouds, and
clear of the granite, in that area.  It was not the biggest deal to
me, but it saved that VFR pilot a lot of time wondering whether he
could go west or not.  He was able to turn southward, then westward,
and continue his trip.

And the best advice I can give you... always drink your hot coffee
from one of those high-quality travel cups with a secure lid.  And
close the little valve at all times other than when taking a sip.  And
if that cup might just start describing the letter “M” inside the
cockpit, then you might want to keep one of those old-style hoods
handy.

[mooneykflyer]

Penetrating any convective accumulation is a less than smart idea and candidly, could be considered as careless and reckless.

When I flew airliners, we had a zero tolerance policy for the very activities that are being described in this thread.

[flight2000]

So where did anyone say they penetrate convective activity in this thread?  Both cloud sets below are cumulus are they not?  One I'll fly through, the other gets a really wide berth or I'll land until it moves along. 

My experience has shown me what my minimums are for flying through a cumulus cloud and I have not seen any major turbulence, hail, or lightning in any cloud that size (or smaller) in almost 15 years of flying with my IR ticket.  If clouds (cumulonimbus) are in the flight levels I will simply go around it or alter my plans if it's to big to go around (i.e. a squall line that extends for a couple hundred miles).  I have no need/desire to fly above 10,000 feet and I base my weather decisions on that starting point.

This thread seems to have morphed into flying through convective cumulonimbus clouds instead of answering what the original poster asked.

Brian

[RJBrown]

Once upon a time in North Texas. I was IFR at about 20 and avoiding build ups. I never entered a cloud but did experience updrafts of over 1000 FPM and hail. I thought I was giving it a wide berth. DONT even get close. I escaped with $35000 in damage and quite a scare. That was about 12 years ago. Never again.

 Repeat: I was never in a cloud. I thought I was a safe distance away. And I was passing to its left as it moved right.

When it happened I made a 90 degree left turn and rode the elevator till IT quit going up. I told center what I was doing. I did not wait for his permission. Simply cleared as requested. Center understood the deviation and once things settled down we re established a altitude and heading.  

[M016576]

Ned- thank you for that post, it was VERY insightful! 

[Stefanovm]

I liked reading Gravel's addition to the thread. I also do not read into the thread any suggestion to penetrate convective activity. Maybe the intent of the other reply was to emphasize positive avoidance?

One scary almost IMC remembrance for me, pre-Mooney in my C152, was from Andrews, TX (E11) to Las Cruces, NM (KLRU), about 3 years ago on a 4th holiday weekend. This was for a trip from 07TS to KFHU that I make about 1 ½ times per year. I fueled at E11, stayed on the ground for a flap problem 3+ hours after coming out of an annual 300 nm behind me. E11 is one third the way to the KFHU destination. My weather briefing was about one hour old when I took off VMC from E11, but in the end a more current one would not have helped. My instrument rating would also have been of little help except it got me on the ground quickly and safely before the fast moving activity got to my location.

Just south of Hobbs, NM, at 8500 msl, I asked my wife if she was seeing the lighting I was seeing WAY off in the distance, just at the horizon. I had no ADF or a strike finder as I do now. Although she said no, I was sure I did, so I radioed Albuquerque FSS. I was told a three hundred mile long squall line had formed from south of the Mexican border most of the way through NM in the last 30 minutes, NOT forecast. The briefer said I could “possibly” get through a hole 150 miles to the north. My decision was an immediate precautionary landing at Hobbs, not my alternate, but the "closest". I flew VMC at the bottom of the yellow arc in too much turbulence for my liking even in VMC direct to Hobbs. I cannot imagine what it would have been like IMC.

In less than the time to divert 40+ miles to the north, land, taxi and tie down, about 60 minutes, the winds were 50 to 60 with up to 1” hail, reported, but not seen by me, and driving rain. Tied down securely and drenched, we took a taxi for a hotel night stay in Hobbs. The FSS was very glad that I gave them the PIREP via the phone from the hotel rather than taking the suggestion to try and maneuver around the weather. The convective activity was very severe and had developed with little to no warning. It rained, with lightning and thunder, for several hours. There was not a convective warning for the route of my flight until it would have been too late to help. The activity was solid for many miles more than my airplane had the capability of diverting around or above.

The bottom line is in always being prepared to avoid convective activity in any way that is necessary. Sometimes it must very expedient, maybe erring on the side of caution, as well as being within your and the airplanes capabilities, even with well meaning suggestions from others. If I had been IMC at the time, the outcome probably would have been very different.

[Stefanovm]

I  just checked on the map and estimate that the line was over 60 miles from me when I noticed it. Of course my C152 was very slow, and the line was very fast moving. Its effects stretched at least the 40 miles mentioned in an above response. Even flying paralell to it, the line closed upon me at an alarming rate. Again stay prepared during convective activity times of the year.

[mooneykflyer]

Towering cumulus (not sure what a cumbulus is) are by formed in areas of deep moisture and convection. Think back to your private pilot training days. There are indeed three elements required for a thunderstorm to form. A TCU is presents all three. Additionally, it's careless, reckless, and quite foolish to be so naive and assume that all will be OK when flying in such a condition.

Cumulus clouds, or fair weather cumulus, are as you said are generally an indication of a relatively small area of instability. However, they're still an indication of convective activity. Generally speaking, they're simply uncomfortable for passengers (or pilots alike who don't like turbulence). The last thing I teach and practice is being an airborne convective activity expert by gambling on which hazards a cumulus (fair weather and TCU) may/may not present.

The towering cumulus clouds are a textbook indication of the first stage of a thunderstorm and as some have described here, are hazardous to small and large airplanes alike. In my profesional opinion, it's an unwise practice to penetrate convective occurences such as TCU.

Quote: flight2000

So where did anyone say they penetrate convective activity in this thread?  Both cloud sets below are cumulus are they not?  One I'll fly through, the other gets a really wide berth or I'll land until it moves along. 

My experience has shown me what my minimums are for flying through a cumulus cloud and I have not seen any major turbulence, hail, or lightning in any cloud that size (or smaller) in almost 15 years of flying with my IR ticket.  If clouds (cumulonimbus) are in the flight levels I will simply go around it or alter my plans if it's to big to go around (i.e. a squall line that extends for a couple hundred miles).  I have no need/desire to fly above 10,000 feet and I base my weather decisions on that starting point.

This thread seems to have morphed into flying through convective cumulonimbus clouds instead of answering what the original poster asked.

Brian

[mooneykflyer]

Quote: crxcte

I know as a pilot we don't fly through towering cumulus clouds.  But, when the clouds are small what is the limit on the height?  I will fly through a towering cumulus cloud when less than 8,000 MSL.  Sometimes its a little bumpy but never bad. 

What is the limit to fly through a towering cumulus?  We never know what the updraft winds are on these things are.

 

[flight2000]

Again, where did I say that flying through convective activity is smart and that I do that or advocate it.   Maybe I'm reading your posts wrong, but I don't consider myself to be reckless, careless, or naive about flying through or around cumulus clouds or weather flying in general.  If I went off your definition of cumulus clouds in the second paragraph and staying clear, I'd never fly IFR in the summer around here to get to the places I need to go.  I use all of the weather data available and more importantly, what I see in the windscreen to make my decisions.  Seems to have worked so far as I've never found myself in a situation to wonder if I was going to come out the other end in one piece.

Another reason I don't like forums to much because of the ease of misinterpretation of posts...

Brian

Quote: mooneykflyer

 

[mooneykflyer]

The OP said:

=I will fly through a towering cumulus cloud when less than 8,000 MSL.= 

and

=What is the limit to fly through a towering cumulus?=

So when you say =So where did anyone say they penetrate convective activity in this thread?=, hopefully the quote from the OP is a concise answer. The phraseology I coined in the second paragraph isn't my personal definition. It's the FAA's definition straight out of the AC 00-6A.

I have no issues flying through cumulus activity or teaching students to do so as long as they understand that generally, they're an indication of an unstable atmosphere, present moisture, and some sort of lifting mechanism; we know where those ingredients generally lead to so, it's again better to be informed and aware.

Cheers!

Quote: mooneykflyer

 

[WardHolbrook]

OK, so how do you guys who fly night XC (VFR or IFR) avoid them?

[Ned Gravel]

I will not fly a route at night if there is any forecast of ACC, TCU or CB along the intended route of flight.  I have neither a stormscope nor XM.  I may consider modifying my personal minima after I get BOTH of those installed.  One is for current tactical situational awareness (stormscope) and the other is for developing and maintaining options in flight to offset poor pre-flight planning (XM weather).

[apenney]

Old thread but really relevant to my stage of flying.  Newly instrument rated 8 days ago.  Started using the rating the next day and have filed an additional five times.  One thing that came up in a trip to Sporty's from Southeast WI was cumulus clouds.  I will never plan on entering a large TC but on this particular trip the formations were very scattered and many were skinny.  Most of the trip I was deviating form them both small and very large.  However, at one point, I entered a small one at 14K feet and I 'm pretty sure it was about 3 times the plane's wingspan in width and lasted for about 5 seconds...but boy was I surprised by the extent of the updrafts.  I'd call it violent.  In that short period of time I rose about 3-400 ft.  Now, I'm coming from my new rating and 250 hour total time perspective.  But I didn't feel comfortable with the level of turbulence in that short encounter.  In retrospect, what else would I expect in them.  Today I'm reading views about personal minimums regarding these and the article above.  Any updates now that its 2019 with new members and maybe revisiting views of members still here?

 

[bradp]

Welcome to IFR flying and all the stuff they didn’t teach you during your rating

[David Lloyd]

About 35 years ago, I flew into an embedded thunderstorm near San Angelo, TX.  This was while receiving vectors from ATC to avoid.  Wife said later that day we weren't going to do that again. Next week we ordered a Stormscope.  Summer in the south and east coast, if you don't plan to weave around activity, you won't be doing much flying. What worked for me, learning over a period of time, was to avoid any area of convective activity as indicated by the Stormscope.  Cumulus clouds that were 12000 feet tall or so, I would fly through.  Taller they are, the bumpier.  Wife's tolerance was less than mine.  Other passengers, more so.  I used that Stormscope for 23 years and staying away from convective activity, never got more than moderate turbulence. Look up the definition of light, moderate and severe.  Many people overstate the level of turbulence.  Light, the approach book stays on the seat.  Moderate, the approach book levitates, then falls to the floor. Severe, the approach book leaps to the windshield, bounces off your head and hides in the baggage compartment.  Severe, I had my car keys come out of my pants pocket.  The OP said towering cumulus.  To me that indicates a tall cloud my airplane can't climb over.  18000 Or more, if not a building thunderstorm will still have up and downdrafts and be more turbulent than you will try a second time.

[apenney]

Well, several items that weren't secured leapt up and scattered including a stratus on the dash and my pulse ox which I keep on a lanyard and around a small hook next to me...they ended up on the floor.  Fortunately, my bag in the rear passenger seat was belted in.  Between that and rising 400 ft  I'll guess that it was moderate...though to me it felt severe!

[donkaye]

On 7/5/2019 at 7:04 PM, apenney said:

Well, several items that weren't secured leapt up and scattered including a stratus on the dash and my pulse ox which I keep on a lanyard and around a small hook next to me...they ended up on the floor.  Fortunately, my bag in the rear passenger seat was belted in.  Between that and rising 400 ft  I'll guess that it was moderate...though to me it felt severe!

Even the big Commercial Airliners deviate around large cumulous clouds.  If you have them around, then you have unstable weather.  I feel most comfortable with the strength of our airplanes, but at 3,000+ pounds they are no match for convective activity that could easily turn into thunderstorms--especially in the afternoon.  My solution is to fly in the mornings and be done by noon.  If there is frontal activity around, then there is always another day for flying, unless you get antsy and choose to risk your life unnecessarily.  Would it be worth it then?  Then you may not have another day.  Remember Scott Crossfield---and he had thousands of hours as a test pilot.

The Instrument Rating is a great rating to have, but for our airplanes it is great for getting through an overcast and flying in stratus with moderate rain. Convective activity in the clouds, NO.  Not even the clouds shown in your picture, which definitely should be flown around.   As you gain more experience and understand the weather better, then the decision making process becomes easier.  At 250 total hours you are definitely not there, yet, as your recently gained experiences shows.  I'd keep it VERY conservative.

Don Kaye, Nine time Master CFI (meaning 18 years) with both SAFE and NAFI