Flying Fires -- Fog, Smoke, and VFR or IFR: Reflections

With this post, I wrap my series on Flying Fires -- Fog, Smoke, and VFR or IFR. The first seven articles in this series were posted from January 4 to 13, 2010. I offer this short piece of fiction as my reflections.

I am a home owner out in the west (U.S.) and there is a wildland fire burning near by. There is no fog near my house. Maybe I am wondering if I am going to have to evacuate. I can see some smoke and the flames but no, there isn't any fog. And whatever winds there are, they aren't much. Maybe 5 mph. I'm preoccupied and somewhat anxious, so I'm not thinking that the usual tanker base tankers fly out of is fogged in. I'm wondering where they are. No winds to ground the tankers. It's getting on to mid-morning and they are usually here by now. Where are they?

I am getting restless. Maybe I'll turn on my radio and listen to a weather report and I'll hear something about fog in some areas of the region. I hope that I will take a breath, sit down, and know that the tankers will get here, it is probably taking them longer to get here because their base might be fogged in.

Ok, I'll wait. I know that the ground crews are out doing what they can, trying to build and hold the line. I can just make out the lights from the engines on the ridge on the other side of the valley below my house. Off in the distance I think I see a helo. There looks to be something hanging from its belly, I think it is a snorkel. Probably getting water from the pond in the park. So, if a helo is out there is hope.

I wait some more. They are here. I see one on the ridge. And another. They are late, but they are here.

I remember the fire several years ago. Woke up one morning to see the smoke hanging in the air down in the valley. I didn't see any tankers or helos over the valley that day. I figured that if I couldn't see into the that they couldn't see either. The guy on the radio said they were inversions. Back then I wasn't all that familiar with the term inversions. Now I am

No inversions today. I can see the valley and the flames. Oh, there is another tanker making a drop. I bet the ground crews are happy to see you! Thank-you tanker pilots and crew!

Flying Fires -- Fog, Smoke, and VFR or IFR: Fires and IFR

Departures

It is rare these days for a tanker to depart in IFR conditions with a load of retardant. We used to do it all the time and it is quite dangerous. After a few years, I refused to depart IFR with a load. The problem comes with the eventual emergency (engine failure,hydraulic failure, fire on board etc.) You have to pitch the load (or crash) and you can't see what you are dropping on. It could be a highway, a house or kids in a play ground. Then there is the very real problem of not being able to get back into the airport you just took off from because it is fogged in. Now you have to fly to your
alternate, IFR with an emergency on board. It's a terrible combination (G, former air tanker pilot).

So what are the options here? You are called to fly a fire, but your base is fogged in. Yes, you are an IFR rated pilot, as is your tanker. One option is to fly empty, under IFR if necessary, to another base with better weather and VFR conditions to load retardant and then fly to the fire under VFR.

Ok, going back to IFR for a moment, the book calls for what is know as a minimum altitude of 2,000 ft above the terrain. You can get down to 1,000 ft above the terrain and lower during an IFR-ILS approach. Consider the air tanker base in Missoula, Montana. Missoula is surrounded by mountains. One of the departure routes out of Missoula, Konna two departure, requires a 350 ft per nautical mile climb. G, who used to fly a P-2, tells me that translates to 1,050 ft per minute climb rate in a P-2 to meet the departure requirements. He goes on to explain what this means:

That's nothing for a modern jet airliner, but a tired old recip with an engine out would be hard pressed to make that kind of climb rate (1,050 per minute). The Missoula One Departure (another departure route out of Missoula) requires 400 ft per nautical mile or 1,200 ft per minute to safely get out of that valley without running into a mountain. Doing even an empty departure in IFR minimums out of a place like Missoula is asking for a whole heap of trouble if you lose an engine. You may not be able to meet the minimum climb gradient with an engine out. In 2000, flying out of Missoula in less than a mile visibility in smoke forced me to change my personal limits. I did it for a couple of weeks and then I decided this is nuts, so I refused. It's the whole idea of 'is this fire really worth injury or death to a civilian on the ground or losing a flight crew and tanker?'

Lives are not expendable.

IFR at fires?

Flying around the fire in smokey IFR is just a guess. There is no Air Traffic Control (ATC) that will even pretend to talk to you if you are that close to the ground. (G)

Remember the 2,000 foot minimum terrain separation that I was talking about earlier? I've covered retardant drops by tanker in other articles, and the tankers are flying at low altitudes when making the drop. Much lower than 2,000 feet above ground level. An inversion can trap smoke from a wildland fire under its lid. Of course smoke can be a problem over a fire without an inversion. A tanker flying in smokey IFR to drop retardant on a fire? Can you even drop the retardant where it needs to go without injuring someone on the ground? Can you drop the retardant without running yourself into the ground or clipping a tree with your wings? So sometimes smokey conditions at a fire can shut down an airshow.

Lives are not expendable.

Fog, remember fog? Fog over a fire might shut down an airshow but fog over a fire is good news for the firefighter on the ground because the moisture in the air aids in suppression efforts

_____________________________


Note (added July 2012): I'd like to thank a couple of my tanker pilot friends whom I corresponded with as I was preparing the articles in this series for their time and help. Here is a complete list of articles in this series with hyperlinks:

1. Introduction (Jan 4)
2. VFR, I can see (Jan 6)
3. IFR, I can't see but I have instruments (Jan 8)
4. Fog (Jan 11)
5. Inversions (Jan 12)
6. Flying fires: VFR or IFR? (Jan 13)
7. Reflections (Jan 18)

Flying Fires -- Fog, Smoke, and VFR or IFR: Inversions

Cold air is denser and heavier than warm air, so cold air sinks and warm air rises.

In a normal airmass, the air cools as altitude is increased. That is, the air is cooler aloft, and helps to move smoke and pollutants out of valleys. An inversion is the opposite of a normal airmass. In an inversion the air aloft is warmer then the air near the ground. Remember that cold air sinks, so the warm air aloft acts like a trap door, trapping the cool air below.

If the airmass is holding enough moisture, fog will form in the inversion because the temperature of the air near the ground is at or near the dewpoint. Smoke and pollutants sitting near the surface are trapped in an inversion.

Like clouds and fog, inversions inhibit visibility, hampering VFR operations.

_____________________________


Note (added July 2012): I'd like to thank a couple of my tanker pilot friends whom I corresponded with as I was preparing the articles in this series for their time and help. Here is a complete list of articles in this series with hyperlinks:

1. Introduction (Jan 4)
2. VFR, I can see (Jan 6)
3. IFR, I can't see but I have instruments (Jan 8)
4. Fog (Jan 11)
5. Inversions (Jan 12)
6. Flying fires: VFR or IFR? (Jan 13)
7. Reflections (Jan 18)

Flying Fires -- Fog, Smoke, and VFR or IFR: Fog

Low clouds that form below 6,500 feet above ground level often reduce visibility thus making VFR flight impossible. There are different types of clouds, forming at different altitudes. If you read a book geared for student pilots, you are likely to find a discussion of different types of clouds. I am not going discuss these different types of clouds here, but if you are interested, NOAA has a nice website on cloud classification that may be found here. For a discussion of cloud types for aviators, The FAA's Pilot's Handbook of Aeronautical Knowledge is available online. Their chapter on weather, which is found in chapter 11, includes a nice discussion of cloud types with some nice pictures.

Low clouds, those that form below 6,500 above ground level (agl) often reduce visibility making VFR flight impossible. Fog is one type of low cloud, and I am going to discuss fog in a little more detail. Fog typically forms when the air temperature near the ground is at or near the dew point. The dew point is the temperature at which the air can hold no more moisture. I found out recently that there are five, no six types of fogs. For those of you who are familiar with discussions of fog, I am using the six types of fogs as referenced in the glossary (under F) of weather terms from the Mt. Holly office of the National Weather Service.

I'll start with the sixth type of fog, ice fog. Ice fog forms in very cold temperatures, e.g. 25 to 30 degrees (F) below zero. It forms in conditions similar to radiation fog (below). Because it forms in such cold climates, ice fog is generally not a factor in aerial wildland fire fighting.

Radiation fog frequently forms at night when the ground is still warm and moist radiates against cold air near the surface. It frequently forms in mountain valleys. As the sun rises and the temperature increases, the radiation fog burns off.

Advection fog forms somewhere else, usually over water when warm air moves over the cooler surface. Wind moves the fog over land.

Sea fog occurs when a very cold and dry airmass moves over warmer water. As the water evaporates, it rises forming fog. Sea fog is then moved along by the wind. Sea fog is sometimes referred to as sea smoke or steam fog.

After a heavy rain, often near a warm front, precipitation or rain induced fog will form. In this case, the atmosphere is saturated with moisture and little if any cooling is required. G, a former air tanker pilot and certified flight instructor offers this observation about precipitation induced fog:

These are the "water dogs" seen rising out of the tree tops after a heavy rain. They are frequently mistaken as smoke by over zealous look-outs in the forest.

The final type of fog is upslope fog. It forms when a moist airmass is forced uphill by wind and the up sloping topography found in areas such as hills and mountain ranges. As the air expands and is forced uphill into the cooler air upslope, the airmass cools to the dew point forming fog.

Why are these different types of fog important to aviators? G explains:

The reason you might want to know the six reasons fog will form is so that you can predict it and decide if its potential will affect the safety of your flight. Fog is fog, but it forms in very predictable circumstances. For example, "It rained like hell this morning, but it is clear and calm this evening. I think I'll go up for a sunset flight and just have some fun." That little scenario is setting you up to where you might not be able to land back at your home port because it fogs in while you are up enjoying the sunset. Did you bring along enough gas to get to a safe place to land? That alternate airport might be a long way away.

_____________________________


Note (added July 2012): I'd like to thank a couple of my tanker pilot friends whom I corresponded with as I was preparing the articles in this series for their time and help. Here is a complete list of articles in this series with hyperlinks:

1. Introduction (Jan 4)
2. VFR, I can see (Jan 6)
3. IFR, I can't see but I have instruments (Jan 8)
4. Fog (Jan 11)
5. Inversions (Jan 12)
6. Flying fires: VFR or IFR? (Jan 13)
7. Reflections (Jan 18)

Flying Fires -- Fog, Smoke, and VFR or IFR: IFR, I can't see but I have instruments

IFR aka instrument flight rules, means that the pilot can not see because conditions are below the minima to allow for visual flight rules. Literally.

A few months ago, I purchased a small scanner and began finding and then listing to the radio frequencies used by near by air traffic. Most of these conversations are one-sided, pilots only, because air traffic control is too far away for my little scanner to pick up. One day soon after I got my scanner, there was a pretty significant rain storm going on. It was clear to me that the pilots I was listening to were not able to see, so had to be flying under IFR. One pilot came over the scanner asking "what's going on down there?" Meaning she may have been asking the controller what she might expect when she reached her destination airport. Or perhaps she was just curious. I could not hear the controllers response, but did hear her say thank-you. A short time later, I heard another pilot ask the same question.

I recently found out IFR student pilots use special glasses where the lateral and forward vision is clouded leaving only clear vision for the instruments. One brand name is foggles. Unless they cheat, wearing foggles means that they can not see out side the cockpit, and must rely on their instruments. Of course, the plane must have IFR instruments that include navigation equipment, one example being a Garmin GPS.

Flying under IFR means that you can fly a plane in or above the clouds. You navigate by flying from way station to way station. Each way station is assigned a specific radio frequency. As I understand it, the pilot tunes the navigation equipment, e.g. garmin GPS, to that radio frequency. Using the instruments in the plane you fly towards that way station. When you pass that way station, you get the frequency for the next way station from your flight plan, which may be on a knee board in your lap and fly towards that way station.

Finally, you are ready to approach the airport where you will land, with what is known as an ILS (instrument landing system) runway. You continue to fly from way station to way station until you reach the assigned frequency for the final runway approach. You pop out of IFR at about 200 feet above the runway, on final approach. When you pop out of IFR, you will be lined up with the extended center line of the runway. (Yes, there is a line down the middle of the runway.) Since you are already lined up with the extended center line of the runway, you do not have to maneuver at low altitude. You make the actual landing under VFR. Many GPS devices used in IFR planes will have these ILS approach plates loaded into memory, when you pass one way station, the GPS finds the next way station from memory and so on up to and including the final ILS approach.

I learned about these way stations, by the way, by listening to my scanner. I often listen to the band used by planes approaching and preparing to fly through the NY airspace in the vector over my house. To give you some perspective, I live on the edge of the class B airspace surrounding Newark-Liberty International Airport. Thanks to my copy of the sectional map covering this airspace, I learned that one of these way stations is located only a few miles from my house.

_____________________________

Note (added July 2012): I'd like to thank a couple of my tanker pilot friends whom I corresponded with as I was preparing the articles in this series for their time and help. Here is a complete list of articles in this series with hyperlinks:

1. Introduction (Jan 4)
2. VFR, I can see (Jan 6)
3. IFR, I can't see but I have instruments (Jan 8)
4. Fog (Jan 11)
5. Inversions (Jan 12)
6. Flying fires: VFR or IFR? (Jan 13)
7. Reflections (Jan 18)

Flying Fires -- Fog, Smoke, and VFR or IFR: Introduction

My first memories of fog go back to our family vacations (long before the days of GPS) camping on the Maine coast. Fog was a not infrequent visitor to our corner of the Maine coast. We couldn't see. I still remember the sound of the fog horn from the light house on the island across the way. I knew that fog horn was important to marine interests because it warned of rock outcroppings, shoals, and the like that were shrouded by fog. I continued to run into fog as an adult, most of these encounters were inland. I always try to drive carefully when it is foggy.

I have a few second hand experiences with smoke as a hindrance to visibility, and these experiences. For several years I lived about four miles from an exit to the NJ Turnpike that was near the Hackensack Meadowlands in NJ. See the image below, look north of I-280 and west of the road marked 95 (actually the eastern spur of the NJ Turnpike). You will see a rather large undeveloped area, that is one portion of the Hackensack Meadowlands.

Every so often there would be fire in the Meadowlands that was bad enough to affect traffic on the NJ Turnpike, I-95, and I-280. There may have been traffic accidents on these interstates where smoke was a major player.

But fog, and smoke are not the only hindrance to visibility. Clouds are also a hindrance to visibility for aviation interests. Not having flown on a commercial airliner until I was about fifteen, I never gave much of a thought to clouds as a hindrance to visibility as a child/. I wasn't to fly again until I was in my early twenties. By that time, I saw that planes could and often did fly above the clouds. Sometimes we wouldn't pop out of the clouds until we were getting ready to land. I had a vague realization that the pilots were using instruments, combined with communications from air traffic controllers to navigate. As time went by, I picked up the vocabulary of visual flight rules (VFR) and instrument flight rules (IFR).

After I wrote my article on winds as affects aerial wildland fire fighting, I got interested in the question of fog and smoke as affects these aerial operations. After some e-mails with a couple of my tanker pilot friends, I knew that I had to begin this series by introducing VFR and IFR where I will provide an overview of each. I'd like to thank the tanker pilot friends whom I corresponded with for their help in this series of articles.

Here is a list of articles in this series (revised after the fact to include links to each article):

1. VFR, I can see (Jan 6)
2. IFR, I can't see but I have instruments (Jan 8)
3. Fog (Jan 11)
4. Inversions (Jan 12)
5. Flying fires: VFR or IFR? (Jan 13)
6. Reflections (Jan 18)