2.5 Reading a Sectional II — Airports and Data Blocks

24 min · UA.II.A.K1c UA.V.B.K6a UA.V.B.K6b

Airport information is the most heavily tested chart skill on the exam, and it is the one that pays off most on real jobs. A data block tells you in about fifteen characters whether there is a tower, what frequency the traffic is talking on, how high the field is and how long the runway is. Learn to read it and you will know more about an unfamiliar airport in five seconds than most people learn in five minutes.

The color rule

This one is short and it is worth full marks on its own.

Blue airport symbol and blue text means there is a control tower. Magenta means there is not. The color applies to the symbol and to every character of the data block beneath it. If you can only remember one thing about airport symbology, remember that.

The symbol family

• Circle with runways drawn inside — a hard-surfaced runway 1,500 to 8,069 feet long, with the runway pattern shown to scale.
• Circle with tick marks around it — services are available: fuel, readily obtainable during normal operating hours. The ticks say nothing about runway length or about whether there is a tower.
• Runway pattern drawn instead of a plain circle — the field has a hard-surfaced runway of 8,069 feet or longer, or multiple hard-surfaced runways. That is the length cue; the ticks are not.
• Plain open circle — a field with only soft-surface runways (turf, gravel, dirt).
• Anchor symbol — a seaplane base.
• Circle with an H — a heliport.
• (Pvt) printed after the name — a private-use field. It is charted for reference, and you have no business landing there, but the airspace and the traffic are real.
• X across the runway — the runway is closed. Closed does not mean quiet; the airspace around it may still be busy.
• Military fields carry the service name and are drawn in blue, since they have towers.

The data block, element by element

A block is read top to bottom, and not every airport has every element. Here is the full set.

Two of those deserve extra attention because the exam leans on them.

Finding the CTAF. The Common Traffic Advisory Frequency is the frequency pilots use to announce their positions at a field with no operating tower. On the chart it is identified by the encircled C placed right after the frequency. At a towered field the Ⓒ usually follows the CT frequency, because when the tower closes that same frequency becomes the CTAF. At a non-towered field it may follow the UNICOM. Do not guess by frequency value — find the Ⓒ and read the number in front of it.

Runway length rounding. Length is given in hundreds of feet, rounded to the nearest 100 with 70 as the rounding point. A runway 8,070 feet long charts as 81; a runway 8,069 feet long charts as 80. The chart also warns that usable length may be less than the physical length.

Part-time towers deserve one more paragraph, because they change the airspace under your feet. When a part-time tower closes for the night, the Class D does not stay Class D. Depending on what the FAA designated for that field, it becomes either a Class E surface area — still requiring authorization under §107.41 — or Class G, requiring nothing. The chart cannot show you which, because the chart shows the daytime picture. The Chart Supplement entry and the tower frequency tabulation give the hours and the reversion. If you plan an evening shoot near a starred tower, look it up rather than assuming.

Used well, one data block answers most of your planning questions before you leave the office: the color tells you whether authorization is likely, the field elevation converts every charted MSL altitude into a real height above your site, the CTAF gives you a receiver frequency, and the RP note tells you which side of the runway to stay away from.

The Chart Supplement

A sectional gives you the airport at a glance. The Chart Supplement U.S. — the book pilots still sometimes call the Airport/Facility Directory — gives you everything else. It is published in regional volumes on a 56-day cycle and is free on the FAA website.

It carries the full runway dimensions and surface, taxiway layout, all communications frequencies with their hours, the airspace notes, obstructions on the approach paths, fuel and services, noise abatement procedures, tower and weather service hours, and remarks specific to that field. When a question asks which source gives the most comprehensive information about a given airport, the answer is the Chart Supplement. That is a published FAA sample question and it comes up often.