Approach Plates Decoded

Click picture for larger image. There are four primary sections to the apporach chart—the briefing strip (blue) with all the necessary frequencies; the plan view (white), which shows an overhead view of the approach route; the profile view (yellow), which depicts the altitudes to be flown during an approach; and an airport view (pink), which shows the layout of runways, taxiways, and other airport information.

The term instrument flight sounds cryptic to many student pilots. But there are a lot of similarities between flight using visual references—the way we're initially taught to fly—and flight by reference to the aircraft instruments. The latter does involve some new skills and tools; an important one is instrument approach procedures, or an approach plate as many pilots call it.

Instrument approach charts come in two varieties: one published by the FAA's National Aeronautical Charting Office (NACO), and one published by Jeppesen. They vary slightly in format and symbology, and some pilots prefer one over the other. We are using a NACO chart for this discussion.

Think of an instrument approach as a roadmap with a series of turns, tracks, and directions that take you to the airport and help you to land safely—or guide you away from the airport if it can't be seen by a specific point. Each approach varies according to the type of navigation equipment it is designed for (for example, GPS versus ILS versus VOR versus NDB). But each chart uses the same basic format to convey the information, and once you understand how this format works, it becomes easier to decipher the many symbols, numbers, and directives.

Here's a chart for the RNAV (GPS) approach to Runway 17 at Summit Airport in Middletown, Delaware. We've divided this chart into five main segments.

Starting at the top, let's examine each segment.

1. Briefing strip (shaded blue). Published along the bottom are the communications frequencies for the airspace and airport, arranged in the order you'll use them. On top are other crucial items, including the inbound course heading (given in magnetic degrees) and directions for the missed approach procedure, which is the route that leads you away from the airport if you cannot see it when you reach your minimum allowable altitude.
2. Plan view (shaded white). This contains the meat of the approach—the initial approach fixes (denoted by the initials IAF enclosed in parentheses), the main approach course (bold black line), and the missed approach (dotted black line). The GPS approach to this airport forms a T; the arms of the T, each with an initial approach fix symbol, represent the waypoints from which you can begin the approach. Follow the waypoints and depicted altitudes to BRLSN, the final approach fix or FAF. Note also the graphical depiction of the missed approach fix and length of the holding pattern, in this case boxed to denote it's too far away to show to scale.

   The plan view shows the airport layout in miniature as well as pertinent terrain features—large bodies of water to the east and west of the airport, and a river that runs just north. To the lower right is a minimum safe altitude circle. As the name suggests, this shows that you can descend to 2,100 feet and remain 1,000 feet above any obstacle within 25 nautical miles of Runway 17—the waypoint on which the MSA circle is based.

3. Profile view (also shaded white, located just below the plan view). If you imagine a small airplane following the bold black line, that's how the approach would look from the side. Like the plan view, the profile view gives the appropriate altitudes for the fixes as well as the inbound course's magnetic heading, and you also see the final approach fix (BRLSN) designated by a black Maltese cross. An abbreviated graphical depiction of the missed approach is included in the upper right corner.
4. Just below the profile view are the minimums for the approach (shaded yellow). The larger numbers indicate the lowest you can go without seeing the runway (608, 619, 600, 660), and the minimum visibility required to do so. The aircraft categories (A, B, C, and D) are determined by your aircraft's final approach speed. The large altitude numbers are msl and the smaller ones next to them are agl. So if you were in a category A aircraft like many trainers, and you reached 608 feet and still couldn't see the runway, you'd have to follow the missed approach instructions.
5. Airport view (shaded pink). A thumbnail sketch of the airport environment, with runways, taxiways, and buildings. The inbound course to Runway 17 is indicated. We also see an obstacle (a 208-foot tower). Just below are listed the runway lighting systems, in this case, runway end identifier lights (REIL), low-intensity runway lights (LIRL), and medium-intensity runway lights (MIRL). The reversed L indicates pilot-controlled lighting.

   Symbols, definitions, and abbreviations for each type of approach are defined and explained in the legends at the front of the NACO approach procedure book. Get to know them well when you decide to begin your instrument training. Knowing them inside and out is a satisfying exercise, especially when you put it to the test on fun and unusual approaches.

Jill W. Tallman is associate editor of AOPA Flight Training and AOPA Pilot magazines. She is an instrument-rated private pilot with approximately 500 hours.