For early pilots, “state-of-the-art navigation” meant road maps given away by oil companies. Can you imagine what those jodhpur-clad aviators would have given for one of today’s marvelously accurate, detailed sectional aeronautical charts?
The cartographers at the FAA’s Aeronautical Navigation Products Group, or AeroNav, are among the best in the world. They process a flood of change information every day, including new information sent in by pilots. If you find an error on a sectional, you can get a new chart free by marking the error on the chart and sending it to the FAA AeroNav group (see “Resources,” p. 39).
Many pilots know only the main features of sectional aeronautical charts. Here are a few interesting details you may never have learned or have forgotten.
Tall Towers and Other Obstructions. The FAA requires towers of significant height to be painted with bands of aviation orange alternating with white. Some must have red flashing beacons or even brilliant white strobes, but when visibility drops, a tall tower can be exceedingly difficult to see. Guy wires are even less visible and just as capable of stopping an airplane.
Did you know that the FAA has no authority to prevent construction of towers or other obstructions, even those close to airports? Builders are supposed to file Form 7460-1 with the FAA for anything built more than 200 feet tall or close to a public-use airport, but they don’t always do that. The best that the FAA can do is object, which is one reason AOPA tries so hard to persuade cities and towns to pass protective zoning around their airports—not only for towers but also for residential encroachment. More than 2,000 public use airports have closed since 1969.
First, a quick review. Towers shorter than 1,000 feet above ground level (agl) are shown on sectionals as inverted V shapes. If greater than 1,000 feet agl, they’re shown as a tall tower, in this example 1,551 feet above mean sea level (msl) or 1,001 feet agl. The actual tower location is more or less the dot at the bottom of the symbol.
A (UC) notation usually means Under Construction, but it also can mean the obstruction has been reported but not verified. In other words, it may not be exactly where shown.
If you see displaced threshold markings on a runway but no obvious obstruction nearby, it may be that a road near the runway is the obstruction. It’s not actually the road that is the obstruction; it’s the height of cars and trucks that are likely to drive along the road. For interstates, the presumed height is 17 feet; for other public roads, 15 feet; and for private roads, 10 feet.
Mind Your MEFs. Should you ever accidentally find yourself in the clouds, a sectional feature called the maximum elevation figure (MEF) could help save your day. But do those figures include towers or other obstructions?
If the obstacle is 200 feet agl or less, no. Higher than that, the FAA’s cartographers figure its height above mean sea level, add 100 feet, then round up that figure to the next 100 feet. A tower with a reported top of 2,424 feet msl will bump up the MEF to 2,600 feet.
A better choice when flying VFR would be to avoid accidentally entering instrument meteorological conditions.
Communications Confusion. It’s easy to forget how useful VORs can be for communicating with a distant flight service station.
Communications frequencies shown above the VOR information box—here 122.2 and 122.4—can be used to talk and listen to the FSS. But does that R after 122.1 mean you should talk or listen on 122.1?
Talk. It means the FSS can (R)eceive on 122.1, but you must listen on the VOR frequency, assuming there’s no line under the frequency indicating no voice capability. It may seem a low-tech way to exchange information in this modern world, but it works just fine, and in sparsely populated parts of the country—such as over the desert southwest where I used to fly—it can be the only way to reach an FSS. The H in a circle at the top right of the box means you can listen for hazardous inflight weather advisory service on the VOR frequency.
Blue Airports and SFARs. If you learned to fly more than 10 or 15 years ago, you were taught that blue airports have either a control tower or a flight service station on the field. Now, blue means only a tower.
Something not often seen on sectionals is the airport name in a box, indicating that special FAR Part 93 rules (SFARs) are in effect for that airport. For instance, there are numerous special rules for Ronald Reagan Washington National Airport (DCA), including one that that prohibits airlines from using that airport for flights over 1,250 miles, thus pushing more international flights to nearby Washington-Dulles International Airport (IAD) and Baltimore/Washington International Thurgood Marshall Airport (BWI).
Other symbols are used for some FAR Part 93 areas, such as the partial circle with feathering on the inside around favorite honeymoon destination Niagara Falls. Those rules restrict flight below 3,500 feet. There are other restrictions too.
Other SFAR areas, including Arizona’s Grand Canyon, use solid lines with a row of small blocks on the inside. Within that large area are sectors and corridors, each with its own minimum altitudes. To make matters more complicated, the rules have different altitudes and routes for companies conducting air tours and other general aviation traffic. If you’d like to read all the requirements for any special FAR Part 93 airport or area, look up the government’s Electronic Code of Federal Regulations (see “Resources,” p. 39).
Military Training Routes. I can personally attest to the thrill of seeing military jets streak by at near-warp speed right in front of a Cessna 172. It was all just a blur.
For military pilots on military training routes (MTR), the usual speed limit of 250 knots below 10,000 feet does not apply. In this example, the VR means it’s a visual route and the arrows indicate it can be flown in both directions. During preflight, check MTR assigned numbers. Military traffic on MTRs with four-digit numbers stays below 1,500 feet agl and above 1,500 feet on MTRs with three or fewer digits. More complete information on each MTR is elsewhere on each sectional chart.
Controlled Airspace and Transition Areas. At country airports, it’s not unusual to practice takeoffs and landings in uncontrolled airspace if the ceiling is a little below 1,000 feet agl and/or the visibility is slightly less than three miles. It’s perfectly legal if you stay in uncontrolled airspace, where the weather minimums are one mile visibility and clear of clouds.
But how can you be sure you’re staying in uncontrolled airspace? That’s where the magenta shading comes in. It shows where controlled airspace lowers to 700 feet agl from the usual 1,200 feet agl. That extra 500 feet of airspace helps protect pilots shooting instrument approaches in IFR weather.
Some pilots wrongly believe that “controlled airspace” means communications are required. Controlled airspace means only that it must be standard visual weather—visual meteorological conditions (VMC), at least a 1,000-foot ceiling, and three miles’ visibility—to legally fly. Just remember that your maximum pattern altitude is 699 feet agl under a transition area.
Flying Near Large Airports. One sectional chart symbol found around large airports is meant to give you a heads-up where you might find bigger, heavier, and faster aircraft. They’re called IFR routes for arrival and departure, and both use small arrowhead shapes to show the direction the routes are normally flown. Arrival routes also include outlines of large, four-engine jet aircraft and include notations of the altitudes often used by that traffic.
One such route for arrivals at IAD is over Virginia’s northern Shenandoah Valley, and there’s nothing quite like paralleling such IFR routes above or below the altitudes shown and seeing a giant airliner majestically gliding past on its way to a landing. The first time can be a little unnerving, and wake turbulence is a consideration.
Sectional charts were designed for pilots who fly at relatively slow speeds, balancing detail against legibility on the charts. If you fly faster, or detest constantly folding and unfolding sectional chart panels as you travel along, world aeronautical charts (WACs) with a scale of 1:1,000,000 are available. Aside from having slightly less detail, such as showing tall obstructions only over 500 feet agl, WACs use nearly identical symbols and markings as sectional charts.
Like to get full value from everything you own? Spend some time with the legend found on the front panel of sectionals or WACs. Remember, a good pilot is always learning.
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