The Season Has Changed

Although the winter season and subsequent threat of icing for pilots are behind us, another familiar seasonal nemesis is upon us. Can you guess what it might be?

I am referring to fog. Silent and sometimes impossible to predict, this weather phenomenon does not always follow the rules. For example, thunderstorms can be predicted reasonably well today and with all the weather aids aboard a Cirrus, it would be unforgivable to put yourself even close to that risk while flying. That is not always true of fog. As you well know, predicting fog (appearance and duration) is very unscientific and even weather models can be, and often are, wrong.

Fog is defined essentially as a cloud either touching the ground or within 50 feet of the ground. Clouds are formed of liquid water drops or condensation resulting from a parcel of air that was either holding a large amount of water vapor and then cooled, or cooled air to which moisture was added. The effect on visibility depends of course on the amount of moisture the air contains or size of the water drops.

Image: Wikipedia, available under a Creative Commons Attribution-Share Alike 3.0 Unported License.

If that isn’t enough, another consideration is slant range (what you can see looking forward and downward) compared to the fixed horizontal visual range as reported by the ground weather station. They are seldom the same. What this all means is that fog, or any phenomenon that limits or obstructs visibility near the ground, is one of the most daunting problems a pilot will face. Some will have acceptable conditions including vertical visibility right up to the point where everything disappears and a quick decision must be made. Others have the runway in sight and cancel IFR and fly right back into hard IMC again. Looking at accident reports, far too many pilots continue their approach when this ugly and sometimes unpredictable nemesis raises its head.

So, what can you do?

For VFR when conditions support the formation of fog:

• If you are a VFR only pilot: do not fly until you are sure take off, en-route, and arrival conditions do not support the development of fog in any form including mountain obscuration. Be sure to check PIREPS before leaving.

For IFR when conditions support the formation of fog:

• Ensure that you spend adequate time in your pre-flight planning and weather analysis. If you are not sure how to use the available weather information to help you, call FSS and ask for their interpretation or engage your instructor/mentor if anything raises suspicion BEFORE YOU GO.
• Get condition updates throughout the flight using on-board information and Flight Watch 122.0.
• Listen to ATC communications with other aircraft. This will sometimes give you a hint or information that has not hit the airport weather data links yet. This is especially true if you are following an aircraft on approach. When switched to the tower frequency ask where the last aircraft broke out. If it is below your personal minimums, immediately plan for a missed approach; do not descend further. Once stabilized and climbing, request vectors to your alternate and get busy preparing.
• Practice in a Flight Training Device such as the full motion FTD’s at SimTrain. This is the right place to prepare for when conditions worsen as you are able to weigh your options, practice procedures, pause the scenario for learning, and debrief in a less stressful environment.

Don’t get caught unprepared. Know the conditions and be prepared if they change.

Cliff Izer

Master Certified Flight Instructor, CFII, MEI, AGI, ATP
FAA Safety Team and Gold Seal Instructor
CIRRUS Standardized Program Instructor
SimTrain, Chief Instructor