Keep your cool

Summertime creates special challenges for flight instructors and their students. When the temperatures start to skyrocket, you need to discuss with your students the many ways heat affects both man and machine. Flight school supervisors also should be aware of the conditions that could represent increased risks for pilots under their oversight.

The following tips deal with the human part of the equation. (For more on how heat and density altitude affect aircraft engine performance, see "Power Struggle," p. 38.) They will provide avoidance strategies, hydration techniques, and some guidelines on reducing the effects of exposure. Finally, you should discuss ways of helping students know when to call it quits. Use these suggestions to keep performance levels high and heat stress low.

1. Avoid peak heating periods. This should seem obvious, but early in the morning is the best time to fly in summer. The availability of the student, instructor, and aircraft all drive the flight schedule, but the hour right after dawn is frequently wide open. The coolest daytime temperatures offer better chances for calm winds and minimal thermal activity. One caution here: Avoid training students only in the more benign conditions. Part of the learning process involves making adjustments for the bumps and grinds of the higher temperatures.
2. Dress appropriately. In hot and dry climates, shorts, sandals, and a T-shirt are not the right kind of flying attire. Take a clue from our desert-dwelling friends and cover up flesh, rather than exposing it. Not only will you save your skin, but you will also stay cooler by trapping perspiration before it evaporates, and you'll get better protection from the sun's rays in the event of an off-airport landing. Another great addition is a good hat with a brim. Baseball-type caps are usually the most practical for flying, but for preflight, consider a hat with a full brim. The floppy "boonie" or safari-style hats are great, plus you can stuff them into your flight bag.
3. Start the lesson fully hydrated. If you show up low on water, you are already behind the power curve. Don't rely on thirst to be your guide. It is very difficult to accurately judge hydration levels. One quick way to check the color of your urine during the obligatory preflight trip to the restroom. If it is yellow or dark, grab a lengthy drink at the water fountain. Be careful with coffee or cola drinks; caffeine is a diuretic, and you could become dehydrated even more quickly than usual. You will be losing water at an increased rate (even by respiration), so it is important to at least start the lesson fully hydrated.
4. Hydrate during the lesson. Prompt your students to take a water bottle along and encourage them to take drinks between maneuver sets. One of the best techniques that I have seen is to fill a flask or water bottle halfway and then freeze it. Before flying, fill the rest of the container with water. The meltdown will provide ice-cold drinking water during the flight. This provides a great pick-me-up after those beads of perspiration start to appear.
5. Ventilate the cockpit during ground operations. Most students figure this one out quickly, but teach them how to use doors, windows, and vents to reduce cabin temperature. Likewise, don't let them sit in line for takeoff with the "doors and windows closed" portion of the checklist complete while the cockpit slowly turns into a dry sauna. Stress appropriate use of the checklist regarding ventilation.
6. Climb to cooler air. During primary instruction, there are limits to how much profile modification is practical, but don't hesitate to climb a little higher to cool down. You might be able to take advantage of the standard ambient lapse rate of 3.5 degrees Fahrenheit per thousand feet of altitude; climbing can improve comfort considerably and reduce heat exposure.
7. Add time between lessons. For multiple lessons, add longer breaks to allow cool-down periods in air-conditioned areas. If a climate-controlled facility is not available, at least find a shaded area. Ramp temperatures can be deceptively high, and a double lesson can give you a thermal thumping! The same holds true for direct sunlight. According to charts in Meteorology for Scientists and Engineers, by Roland B. Stull, direct sunlight will raise the heat index another 15 degrees. Conventional wisdom cautions us to be especially careful between 11 a.m. and 2 p.m. when the sun angle is high, although peak temperatures can occur much later.
8. Know your limitations. Recognize that prolonged heat exposure will result in unpredictable degrees of diminished capacity. A major problem with thermal stress, dehydration, and fatigue is that there is no real way to qualify how much a pilot's judgment and performance have degraded. People vary, and the heat-stressed individual is often unaware of his reduced decision-making ability. If you notice a definite decrease in student performance on a hot day, consider the heat as a factor. You might first notice a few muffed radio calls or checklist errors. Pay special attention during pattern work. Four or five good landings followed by progressive deterioration might mean your student is overheating.
9. Know when to quit. There are some days when it is just better to knock off and opt for a ground or simulator lesson. Thunderstorms aren't the only reason for weather cancellation. Canceling can be a tough call considering how CFIs earn a living, but sometimes it's the right call.

Flying in the heat is a fact of life during the summer months. Even pilots in the Dakotas will encounter some days when the heat might force some adjustments or cancellations. These tips will help you make the best of high-heat situations while maintaining a good safety margin. As always, the role of the instructor is critical in teaching new pilots how to cope with extremes. I once allowed a student to fly too long, and I was shocked by how exhausted he looked when we were finished.

People are different, but one thing is certain: If they are overheating, they probably aren't having fun. They probably aren't learning much, either. Remember, unless you ask, the student may be reluctant to admit he or she is cooking. Don't wait until the frustration factor ramps up. Keep a handle on how much is enough during the dog days.

And don't forget about your own requirements. Students seldom fly three or four times a day, but CFIs frequently do.

Dave Hensley is manager of standards and curriculum at Regional Airline Academy in DeLand, Florida. A former Air Force U-2 pilot, he is an aviation safety counselor, a Master CFI, and a Civil Air Patrol check pilot. He has more than 7,600 flight hours.