It was winter in the Tahoe Sierra and the desert basins. A cold front just went through, a high pressure was building. It was predicted to be clear and sunny.

The next morning it was totally socked in and even foggy. No wind. Further research found out that it was sunny up high in the ski resorts. Hope came back. A serious inversion of cold air settled in the valleys with warmer air above. This created a layer of clouds probably 300 to 800 feet thick.

Loretta had’nt done much cloud flying. Since many times, clouds mean bad air, she was anxious to do some “flying with the dragons” as she calls it.

We calculated it was worth the trip to the airport hoping the clouds would burn off as the sun heated everything.

The airport was socked in with a thick cloud layer. Good thing it was a Class G airspace airport for this type of flying. The ceiling was about 800 feet above the surface and not much more. The air was still, dark and cold. No general aviation traffic could either get in or out with the clouds so the Carson City, Nevada airport was silent until the Rotax two cycle started to idle.

A perfect time to hang around the airport and do some practice patterns with touch and goes in the calm air. Once we were up, it was nice air and it was starting to open up near the hills. We fly directly towards the sun shining through the clouds. As we got closer, we could see the hole was growing from the light shining through on the ground.

The hole was large enough to make it through. As we climbed next to the clouds the sensation of movement was a new experience for Loretta, “When you’re normally flying, you many times feel motionless. The clouds provide a captivating sensation of speed I have never experienced before”.

The cold moist air had pooled in the valleys had formed a stratus cloud layer just below the inversion. No vertical movement of the air at all. The moisture at the top of the inversion layer cooled enough the night before to condense and form the level clouds.

We could feel the warm air above as we climbed through the inversion. The warm air and the hot sun in your face was welcome to the cold and dreary morning. We climbed above into the warm blue sky with desert mountains clear of clouds. We had a nice ground reference next to the carpet of clouds.

As we climbed above, we could see many new holes forming all around as the clouds burned off. We were dressed for the cold with 12 volt electric gloves, so we decided to climb. We wanted to see what was blanketed and what airports might be open.

The mountains about ski area base elevation (8000 feet MSL) was clear and Lake Tahoe did not have an inversion. At 12,000 feet it did get cold, so we headed back to the airport. Calm air followed us all the way to landing. This was Loretta’s first flight through an inversion layer and closest ever to the clouds.

In This Flight We Learned:

1. Do your weather research to see if what you see is what you get

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2. Stratus clouds mean calm air with little vertical air movement, and generally pleasant air to fly in.

3. Inversions are amazing weather phenomenon with a pool of cold air below and warm air above.

4. We could fly this close to the clouds because we stayed in Class G airspace, where we can be “Clear Of Clouds” ground level up to 1200 feet AGL.

WARNING

Do not try this at home. Flying near clouds can be dangerous for two reasons. First, clouds create weather because of the change of state from air moisture to water droplets, and water evaporating and creating cold air and resultant downdrafts. Second is visibility – having a visual reference with the ground and being able to see other aircraft, and them see you.

Get many hours experience and know your cloud clearances for the airspace you are flying in before you fly near any clouds.

Dennis PAGEN, expert in micrometeorology and Sport Pilot weather said, “A cumulus cloud is the top of a thermal updraft”. This is true and will be the basis to our flight adventure today.

The concept is not to be scared of any cumulus that pops in the sky, but to know what type of air you will be entering based on the shape of the cumulus cloud. As we know from the weather to fly system, moisture and clouds can form their own weather.

The Good

Lets start with the good. The cumulus clouds that provide some texture to the skies, provide us enough bumps for moderate turbulence, and provide us flying conditions that will not bring us any bad or ugly stories.

Simply, the good cumulus are wider than they are tall. We know and see these all the time. It looks like a nice day. The cumulus are there but not that tall. You read the upper air tables and the air cools the typical 2 degrees C per 1000 feet altitude increase.

If you are used to flying in perfectly smooth air you may even be scary flying with nice looking cumulus in the skies. If you are an experienced instructor, you tell your student “these bumps are normal. This is typical for this type of flight”. You are not scared, but you are on your toes because the air is moving up or down and it is a significant factor in your flight.

The Bad

We move to the bad. This is where the thermals are stronger, the air is going up faster and down faster. This is where you start to wonder. You read the upper air tables and the air cools from 2 to 3 degrees C per 1000 feet altitude increase.

It is simply when the Cumulus clouds are as tall as they are wide. This could be considered an average nice day by the normal person walking on the street and looking up in the sky. Afternoon clouds predicted and a slight chance of a thunderstorm. If you decide to fly on an unstable day and fly in the late morning this will effect you.

This is the medium to severe bump tolerance zone. It is bad but it is not ugly. You maintain positive control of the aircraft most of the time but there are definite altitude and attitude changes as you fly though the bumps. This is where the flight instructor informs the student that this is normal but it will be bumpy. This is where the instructor is on his toes and must provide active control near the ground. Things could go bad if you are not experienced or you depend on a student to account for a down draft near the ground.

The UGLY

We now address the ugly cumulus. This is where the clouds look pretty, but the air is ugly. This is where most of us hope not to ever be, and we can plan on not being there. The cumulus clouds are taller than they are wide. The day starts of very nice and forgiving, but can go bad fast and get past any light sport aircraft limitations quickly. You can tell if it is going to this type of a day from the upper air charts with the air cooling from 3 to 4 degrees C per 1000 feet, or the weather people predicting there are going to be thunderstorms in the afternoon. If you have to simply watch the skies, you will see bad looking cumulus early in the day as discussed above, or medium cumulus clouds very early in the day.

Ugly air means lack of control and a good chance of a bad landing. Ugly can be avoided through using the basic "weather to fly" concepts.

Keep in Mind

1. Cumulus clouds are formed from enough moisture in the air rising and condensing, but if the air is dry and the sky blue you can still have the thermals with no clouds.

2. Ugly air cumulus can also be bad looking cumulus with higher wind looking tops. This is where you combine bad looking cumulus with wind creating the ugly situation.

How Can You Avoid the Bad, and Especially Ugly Air?

1. Fly early in the morning before the sun has a chance to heat the ground.

2. Study the weather and fly later in the morning in stable conditions.

3. Try and fly when the surface conditions are not different from the upper air 3000 feet above you.

Evaluate “Whether to Fly” and pick the good, minimize the bad, and completely avoid the ugly cumulus. Clouds provide for you markers in the sky to tell you what the air is doing, but they need to be approached with caution since they can create their own weather.

Always consider what you might have to do to get more airtime per flight and being prepared to fly in the cold will help this. Many times some of the most beautiful flying will be when it is cold.

The concept of just dressing warm to fly in an open cockpit airplane when it is cold works good most of the time. However, many people believe just dressing warm will work if it gets REALLY cold. Most of the time you need some sort of auxiliary heat to fly for and hour or more. I have tried it, it does not work.

If it is just below freezing (30 degrees F) with a 30 MPH wind chill (this is a slow PPC speed for example) this equates to -2 degrees F below zero wind chill. If it is a little faster and colder this can easily drop to –20 below zero wind chill. This is really, really cold. If your hands are out in the wind whey will not last.

Everyone I have seen dressing good with warm looking bar mitts and/or good gloves, can last maybe half an hour if it is really cold, than come back in agony with frozen hands.

The one I remember best was when it happened to me. The day started in Truckee California, sometimes the coldest place in the US. It was calm and nice, about 25 degrees F. It was a 30 minute flight to get back to my home airport but had to climb to 10,000 to get over a ridge and back to Carson City Nevada. I knew it would be cold but I did not expect what happened. While flying back 15 minutes into the flight, my hands got so cold I could not grab onto the bar. Flying it with the bar under my elbows seemed to work best and also squeezing the bar between my forearms provided enough control to safely land. What a lesson to learn! Something had to be done to fly when it was really cold.

The heat pads used by hunters to put in their gloves and boots are a great start. They are generally inexpensive and can be carried and used as required if you generally do not plan to consistently fly in the cold and really cold but could be used if you need them.

I soon discovered that the motorcycle shop had 12 volt electric gloves, socks, pants and jackets. The problem is solved. Hook this to your battery and you have a very efficient heating system for any 12 volt aircraft system. Think of the extra comfort and enjoyable time you can spend in the air. Great technology we can use from our motorcycle cousins. This will apply to all 12 volt aircraft systems, including enclosed aircraft with marginal heating systems.

You can easily run two pairs of gloves and one pair of socks off a common Rotax 2 cycle engine with a battery. If put some of those “hunter heat packs” near the students toes, and you can easily fly around for 2 hours in comfort dressed warmly. Heated gloves and socks running full blast provide plenty of heat when you also dressed warm. I added a simple voltage meter to the aircraft battery to help figure out if the system was charging or draining.

Each pair of gloves and socks are 22 watts – each totaling 66 watts for 3 sets.
This is quite a bit of juice. A hand held radio is only 5 watts output. Producing heat takes a lot of electricity. My simple ROTAX 503 puts out about 175 watts at full power and significantly less at idle. Adding a jacket at 77 watts in addition overloads the electrical system and drains the battery at idle but can produce enough electricity at 5500 RPM cruise. If you want the extra heat, perhaps a vest at 44 watts will help you squeak by.

Also note that if you bring something along to push the radio buttons since this is near impossible with big gloves, you do not have to take off your gloves to change frequencies. A pencil eraser works great for this.

When it gets cold, turn your half hour flights of suffering cold into 2 hour flights where you are warm and cozy.