When was the last time you used a sectional chart on a balloon flight? For some, I’m willing to bet it was when you studied for your last rating test. Still, as pilots we are expected to know how to read and use a sectional (officially known as the National Oceanic and Atmospheric Administration Sectional Aeronautical Chart). Who says so? No less an authority than the FARs.
FAR Part 61, subpart D-Private Pilots, §61.105-Aeronautical Knowledge. An applicant for a private pilot certificate must have ... satisfactorily completed a course of instruction or home study in at least the following areas of aeronautical knowledge... (e) Free balloons (2) The use of aeronautical charts and the magnetic compass for free balloon navigation.
Granted, a sectional is not the best tool for navigating a balloon on our typical flights of 1 to 10 miles in distance and 45 to 90 minutes in duration. The problem is one of scale. Any map or chart is a representation of a portion of the earth’s surface. Naturally the scale cannot be 1 to 1. In the case of a Sectional the scale is 1:500,000 or 1 inch = 6.86 nautical miles. Given the typical balloon flight as described above, the distance traveled on a sectional would be a mere inch or two at most. Naturally the cartographer cannot show all of the surface features, roads, terrain, obstacles, etc. in such a small space. Even though in theory a Sectional is, according to the Airman’s Information Manual, designed for the visual navigation of medium and slow speed aircraft (and you can’t get much slower than a balloon!), in practice, a simple road map is generally much more useful for the type of "where am I now?" navigation we balloon pilots practice. Still the sectional can and does provide very important and needed information. For the purpose of example let’s consider one of my own recent flights...
Since returning to Texas almost three years ago, I have consistently tried to take my brother-in-law and a former school teacher for their first balloon flight. As it happens, I wanted to do so in my hometown (and theirs) of Beaumont, Texas. Each time I went home to visit my parents I dutifully carried my balloon. Each time the weather was bad; low clouds, high winds, rain, etc. But, on my most recent visit home for Thanksgiving last November, the weather forecast finally looked promising for the weekend. Arriving on Wednesday, I monitored the weather until the forecast promised light and variable winds for Friday evening and into Saturday morning.
My parents live just a stone’s throw from the municipal airport. It is a typical small town airport with one paved landing strip, no control tower, etc. It houses a skydiving operation and many local pilots first learned to fly there while the nearby Jefferson County airport handles the airline traffic. Because I had never flown in Beaumont, my flight planning called for a CNT into the airport because I knew it offered a wide open and safe landing zone with easy retrieval. A launch site would be chosen based on wind direction at the time of flight.
My preflight began with a trip to the airport to confirm permission I had received on an earlier trip to fly into or out of the airport. (As a registered aircraft I didn’t technically need this permission, but felt it was courteous to ask). Permission renewed my next step was to purchase a current Sectional for the area. From this I learned many things that would impact my flight. Among them were:
Airspace: I would be flying in Class E airspace. Nearby Jefferson County airport hosts a TRSA (Terminal Radar Service Area) but the ceiling for that service began at 1,600 feet AGL. So long as I remained below that altitude I would not need to make radio contact.
Field elevation: The airport’s field elevation is a mere 32 feet above sea level. Why is that useful? It allowed me to set my altimeter to the proper elevation rather than the old "set it to zero" method. I also learned that the highest topographic elevation in the entire area was only 800 feet MSL.
Magnetic Declination: Since Jefferson County Airport also has a VORTAC, the sectional included a magnetic compass rose (already aligned for magnetic declination) which allowed me to easily orient a compass rose on the city road map that would serve as my primary navigational tool for the flight. Of course even without the indicated compass rose, I could still find the magnetic declination on the sectional. How? By finding the Isogonic Line - a line on a map joining parts of the earth’s surface at which the magnetic declination is the same. The Isogonic line on a sectional is indicated by a dashed maroon line with a notation such as 2 E.
Radio aids: Flying into an airport of any size you should always be aware of the need for any required communications. Again my sectional tells me the Beaumont Municipal Airport is a non-controlled airport, however it also notes that 123.0 is the Common Traffic Advisory Frequency (CTAF). As such, traffic in and around the airport is expected to broadcast their location and intentions. Thus upon launch I dial up the frequency on my aircraft radio and call, "Beaumont Municipal-Hot Air Balloon 44599-five miles southeast, climbing to 1,000 feet, inbound for landing on the ramp." I make similar calls when I am one mile out, when I cross the boundary of the airport property and as I begin my descent to land. I also report "down and safe" after landing. Though no one responds to my calls, I am assured that other air traffic is aware I am in the area, and the final report helps quell any unsuspecting reports of a balloon crash at the airport. That may sound strange but once, while contouring along the treetops in my local area, I had a woman follow the balloon for several blocks, stopping at each intersection to yell, "Are you OK?" I think perhaps she had seen one too many episodes of Rescue 911 or something. You can never be too sure who might pick up the phone to report what they think is a disaster.
Of course, had the unexpected happened and I needed to declare an
emergency while in-flight, the sectional tells me the tower frequency for
nearby Jefferson County airport is 119.5. Even though not in their
airspace, they would be close enough to report an emergency "mayday" and
get help rolling in my direction. The emergency frequency for VHF radios
is 121.5 MHz.
En Route Obstructions: another useful feature of the sectional is that it will identify obstructions in two categories; those 1,000 feet and higher AGL and those below 1,000 feet AGL. For my flight I was forewarned that there was a group obstruction near the southeast corner of the airport. The chart also informs me these towers are 331 feet above sea level and 300 feet AGL.
ATIS: Having grown up here I already know that the Jefferson County airport is a short distance away (about 20 miles); close enough that all the local media use it as a weather reporting station. So, by checking my sectional I find that Jeff County (BPT) has an ATIS broadcast on 126.3--an excellent way to check weather just prior to launch and while in-flight.
The sectional chart also provides a wide variety of additional information. It will identify major highways, railroads and even powerlines of the serious "hummer" nature. Certain visual landmarks are also noted such as bridges, aerial cables, outdoor theaters, race tracks, water, oil, or gas tanks, and much more. So with all of this useful information, why aren’t sectionals used more for balloon navigation?
The problem, as noted above, is one of scale. At a scale of 1:500,000 the entire city of Beaumont, Texas is a yellow blob on a sectional barely 1-inch across. The area that I flew over, from launch to landing, even less. It is impossible for the cartographer to note all the roads, schools, intersections, parks, and other landmarks usually needed for a balloon flight. Thus we typically navigate off of the best possible road map, which takes that 1-inch area of the sectional and enlarges it to about three feet.
So with the help of my sectional chart, when it came time to make the above flight, I transferred a compass rose onto a city road map, aligning it for magnetic declination. Equipped with a weather briefing including wind speeds and direction, I selected a launch site and off we went. We launched in light winds and about 40 minutes later made a stand up landing at the far end of the airport property, well clear of the active runway. At last my brother-in-law had his balloon ride! (My former teacher was out of town for the holiday.)
While the sectional chart may not be the best tool for balloon navigation, it is a useful one. If it has been some time since you actively used one in preparation for a flight, you might try taking a little test Balloon Life has devised. Assuming 5 points for each correct answer, score as follows:
