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This week's Fly Like a Pro Series helps prepare for Summertime Flying.Springtime is well in progress; we are leaving the usually confused weather that characterizes the end of winter is well behind us and the temperatures are beginning to climb. Now is a great time to start thinking about the summer flying season ahead—the kids will be getting out of school, there are trips to be made, and a world of flying destinations are just waiting for your arrival. Summer can be a great time to get some flying in, but it comes with its own set of special challenges that bear thinking about.
If there is any meteorological phenomenon that you could use to characterize summer, thunderstorms would be it. Depending on where you are in the country, you may already be starting to notice a rumble of thunder or two in the afternoons. While thunderstorms associated with frontal systems happen twelve months out of the year, the air mass thunderstorms caused by diurnal heating (daily heating from the sun) become much more common place in summer. While these thunderstorms are rarely severe, they can pop up and grow with astounding speed.
A look at the weather with your morning coffee and a peak out of the window can give you a good clue as to whether you’ll experience air mass thunderstorms later in the day. Warm temperatures of 26°C with a dew point greater than 15°C should arouse your suspicions. If you look out the window and see lots of morning haze, you know that the air is saturated with moisture. As the sun rises, the heat will lift that moisture into the atmosphere and create the cumulus precursors to summertime thunderstorms. Take a look at the winds aloft, too; air mass thunderstorm development depends on relatively calm winds aloft. High wind speeds aloft will shear the tops off of the cumulus clouds and inhibit development into full-fledged summer storms.
The geography of the region you live in also affects the likelihood that you’ll have to contend with summer boomers. The presence of cool water off on the west coast of the U.S. makes for relatively stable air masses and few thunderstorms. The east coast of the U.S. is lousy with thunderstorms on a hot summer day; you might as well paint much of the radar screen red. The Gulf Coast of is much the same. Anywhere that you have ample moisture, the heat of the dog days of summer will provide sufficient instability for the formation of thunderstorms. Coastal areas along the East Coast are particularly susceptible to a phenomenon known as a “sea breeze front.” This are small scale weather systems that are formed when the onshore flow of moist air from the ocean in the afternoon collides with the prevailing westerly winds; the sea breeze and heat provide more than enough lifting action to form some pretty impressive looking thunderstorms.
Any fool knows that flying through a thunderstorm is a dumb thing to do. You want to avoid them; but how far is far enough? For summer air mass thunderstorms, you’ll want to be at least five miles away on the upwind side of the storm and clear of any visible cloud; don’t fly underneath any portion of the storm. You’ll want a bit more distance—about ten miles—on the downwind side. The winds will push the turbulence downwind and you can experience significant turbulence even if you are well clear of the clouds. Frontal thunderstorms, which tend to be far more severe, a very different sort of beast; 20 miles upwind and 50 miles downwind is not a bad rule of thumb. Remember, the most southwestern cell in a line of storms is typically the most intense. Give especially wide berth to these storms.
A quick word on airborne weather information: If you have weather radar, it is a good idea to check that it is functioning well and that the radome is in good shape before the summer season really gets started; nothing messes up radar like a chipped up and dirty radome. Also, be especially wary of airborne weather services like XM Weather or your favorite weather app on your iPad. While these are great for planning and general awareness, they do not update frequently enough for in-close weather avoidance. A good saying is this: “One peak is worth a thousand sweeps”—if it look gnarly out the window, it probably is. Just stay away.
Hot makes High
The summer heat does a lot more than make you sweat a bit in the cockpit; it also can be extremely detrimental to your aircraft’s performance. While you should ALWAYS do performance calculations prior to each flight (you do, right?), it becomes really important during the heat of the summer. This is especially true for those of you operating from high altitude airports. If you fly in the mountains, you already know that density altitude is a very real threat to your safety.
When you are calculating your takeoff and landing numbers, it is important to understand what they represent: the charts are based on a perfect airplane and perfect pilot technique. As much as we love our airplanes, they probably aren’t as pristine as they were they day they rolled out of the factory. We are good pilots, but are we perfect? Probably not.
There is more to density altitude than just the temperature, too. While most manufacturer charts don’t account for humidity, high humidity has the effect of increasing density altitude. If the dew point and outside air temperature are close together, your performance numbers are probably a tad on the optimistic side.
There are other factors to consider: how confident are you in your weight numbers? What about local, small scale weather phenomenon? Tall, shady trees at the end of the runway can create a small current of descending air, as can air blowing across a small hill on the upwind side of the airport. Those sorts of things can detract from climb performance right when you need it most, so really take a good look at your environment. Adding a safety factor to your performance numbers isn’t a terrible idea—for a pilot of average experience, a 25% cushion is a good place to start.
Be sure to consider engine performance as well. Many pilot operating handbooks require the mixture to be leaned above a certain altitude; one old Cessna manual says 3000 feet. A 95°F day with high humidity can easily make the density altitude of a sea level airport 2500 feet or more. Expect to have to lean the engine out to get the maximum amount of power for takeoff.
Summer Preflights—the Airplane and Yourself
Of course, you always do a thorough preflight prior to every departure. Summer flying adds a couple of items to your list of things to check and a few things that warrant additional scrutiny. Summertime means humidity in most parts of the country, along with the pounding rain that is emblematic of summer showers. Checking the fuel for contamination is essential; half full tanks that have been left to sit for a while can accumulate a surprising amount of water. Engine cooling is always important, but it is even more critical in summer time. Making sure that there are no bent cylinder fins and that the cowling baffles are in good shape and correctly installed can go a long way towards ensuring that your engine operates at peak performance.
Most of our light aircraft aren’t air conditioned, so preflighting yourself is just as important as checking out the airplane before flight. If you aren’t well rested, fed, and hydrated, you are much more susceptible to the effects of heat. Bringing along a good sized water bottle that can be safety secured in the cockpit is a big part of staying safe in hot weather.
Keep Your Head on a Swivel
If you are looking forward to getting more flying in during the summer, you can bet lots of other pilots feel the same way. According to the FAA Aviation Safety Information Analysis and Sharing System’s data on reported near mid-air collisions, nearly 40% of the near misses that occurred in 2016 happened between June 1st and August 30th. Everyone is out flying, so that means that you must have your collision avoidance game on point.
Most midair collisions occur within 5 nm of an airport. To avoid trouble, make sure that you use the proper CTAF frequency and avoid the temptation to shortcut the pattern entry; do it the way it tells you to in the AIM so that everyone knows what to expect. As you climb or descend, get into the habit of making shallow turns to the left and right to clear the area hidden by the nose. Make good use of flight following from ATC, and do your best to avoid the crowded areas: Over the top of VORs, underneath class B airspace, and on the centerlines of victor airways. Summer is a great time to re-establish your good scanning habits—keep your eyes outside, since see-and-avoid is both your responsibility and your last line of defense.
Now, Go Have a Great Time!
Summer is a great time to take the family to a new place, see the sights from aloft in an unrushed fashion, or introduce a friend to the miracle of flight by grabbing that $100 hamburger. Staying vigilant for cues to changing weather, remembering that density altitude is a big deal, preflighting yourself as well as your aircraft, and keeping your eyes peeled for traffic will not only ensure that you have a lot of fun, but you’ll be flying safe as well.