What do the numbers next to a tower on a sectional chart mean?

Two heights in two datums. The upper figure is the elevation of the top of the obstruction above mean sea level; the figure in parentheses under it is the height of the structure above the ground. Part 107’s altitude limit in § 107.51(b) is written in feet above the ground, so the parenthesised figure is the one that talks to the rule — and within 400 feet of the structure it is the one the 400-foot allowance is measured from.

What is the difference between a magenta and a blue airport symbol?

Colour means tower. The Chart Users’ Guide: airports with control towers and their related data are shown in blue; all other airports and their data are shown in magenta. Since a towered airport almost always sits inside Class B, C or D, the colour is also the first hint that § 107.41 will require ATC authorization.

What is the large blue number with a small raised digit in each box of the chart?

The Maximum Elevation Figure. It is the highest elevation in that quadrant — terrain and obstacles included — in thousands and hundreds of feet MSL, rounded up to the next hundred with the last two digits dropped. A 3 with a raised 4 is 3,400 feet MSL. It is a ceiling on what is in the box, not the height of any one thing.

What is the difference between a restricted area and a restricted airport on a chart?

A restricted AREA is special use airspace: a blue hatched boundary labelled R and a number, such as R-4401, with invisible hazards like artillery firing inside it. A restricted or private AIRPORT is a magenta circle with an R inside it, charted as a landmark because it is not open to the public. They share a letter and nothing else.

What does VR1007 or IR21 on a sectional mean?

A military training route, flown fast and low by military aircraft. IR is flown under instrument rules regardless of weather, VR under visual rules. The number’s length is the read: four digits means no segment of the route is above 1,500 feet AGL; three or fewer digits means at least one segment is. The route can be several miles wide either side of the charted line.

How do I read the runway length from an airport’s data block?

It is the figure after the lighting code, in hundreds of feet — 72 is a runway of about 7,200 feet. The FAA rounds with 70 as the break point, so a runway of 8,070 feet is charted as 81 and one of 8,069 feet as 80, and the usable length may be less than the charted length.

Sectional chart legend

The airspace boundaries are one page of the legend. The rest is what this page drills: what the airport symbols mean, how to read the block of figures under an airport name, which of the two numbers beside a tower is the one Part 107 cares about, and what the hatched areas, route designators and big blue figures are. Look first, check the key after.

Read the symbol

Each excerpt is drawn from numbers by this site, using the symbology the FAA’s Chart Users’ Guide defines — the same shapes, colours and conventions, cited under every answer. They are simplified and they are not FAA charts. What you learn here transfers to a real sectional, and it is worth opening one before test day.

Sectional chart legend 1 of 8

What does the symbol on the excerpt mean?

Airports

The shape says what the runway is; the colour says whether there is a tower. Ticks around the symbol mean fuel, and a letter inside it means the field is not what it looks like.

A public-use airport with a hard-surfaced runway 1,500 to 8,069 feet long
An airport with a hard-surfaced runway longer than 8,069 feet, or several hard-surfaced runways
A public-use airport whose runways are not hard-surfaced, or whose hard runway is under 1,500 feet
A restricted or private airport — non-public use, charted because it has landmark value
An abandoned airport, charted only as a landmark or to avoid confusion with a usable field nearby
A seaplane base
A heliport
Fuel is available at this airport
An airport with an operating control tower — its symbol and data are printed in blue

The data block, in the order it is printed

Under every airport name sits a short block of frequencies and figures. It reads left to right, top to bottom, and every position means one fixed thing — which is why the same figure, 72, is a runway length on the last line and would be nothing anywhere else.

NAME (ID): The airport’s official FAA name and its location identifier. Blue if there is an operating control tower, magenta if not — the fastest read on the chart.
CT - 118.3 *: The control tower’s primary frequency. A star after it means the tower is part-time; the chart’s tower tabulation has the hours.
Ⓒ: The circled C follows the Common Traffic Advisory Frequency — the frequency manned pilots use to announce position and intentions, and the one a remote pilot monitors.
ATIS 124.1: The recorded terminal information broadcast. Where there is no full-time ATIS the automated weather (ASOS/AWOS) frequency is printed instead.
1249: Airport elevation in feet above mean sea level — the highest point on the usable landing area. Read it in the same datum as the obstruction figures nearby.
L · *L · –: Runway edge lighting: L is lights on from sunset to sunrise; *L means limitations, see the Chart Supplement; a dash means no edge lights.
72: Length of the longest runway in hundreds of feet — 7,200 feet — rounded with 70 as the break point, so 8,070 charts as 81 and 8,069 as 80. Usable length may be less.
122.95: UNICOM, the aeronautical advisory station. It is not automatically the CTAF; the circled C tells you which frequency is.
RP 18: A right-hand traffic pattern for that runway. Left is the default, so RP is printed only where the pattern breaks it — and it tells you which side the manned traffic turns on.

Obstructions

Two glyphs by height, one for a group, one for a wind turbine. Beside each sit two figures: the top of the obstruction above sea level, and — in parentheses — its height above the ground. The second is the one § 107.51 is written in.

A man-made obstruction less than 1,000 feet above the ground
A man-made obstruction 1,000 feet or more above the ground
A group of obstructions — only the highest one is charted, to keep the chart legible
An obstruction fitted with high-intensity strobe lighting
A wind turbine
An obstruction under construction, or reported but not yet verified by the FAA

Special use airspace, and the other lines

Hatched boundaries with a label. Blue for the three that restrict — prohibited, restricted, warning — and magenta for the two that caution, alert areas and military operations areas. A grey line with IR or VR on it is a military training route, and the symbols in the last group mark activity you check NOTAMs for.

On the chart	What it is
P-40 blue hatching	A prohibited area — flight of aircraft is prohibited inside it
R-4401 blue hatching	A restricted area — flight is not wholly prohibited but is subject to restrictions, and the hazards are often invisible
W-237 blue hatching	A warning area — hazardous activity in airspace from 3 NM offshore, where the U.S. does not have sole jurisdiction
GAMECOCK MOA magenta hatching	A military operations area — military training activity, separated from IFR traffic but not closed to VFR
A-211 magenta hatching	An alert area — a high volume of pilot training or an unusual type of aerial activity
VR1007 · IR21 grey line, black designator	A military training route. IR is flown under instrument rules, VR under visual rules; four digits means no segment above 1,500 feet AGL, three or fewer means at least one segment is. Several miles wide either side of the line.
3⁴ large blue figure per quadrant	The Maximum Elevation Figure: the highest terrain or obstacle in the quadrant, in thousands and hundreds of feet MSL, rounded up to the next hundred — 3,400 feet here.

A parachute jumping area — jumpers and their aircraft may be overhead
An unmanned aircraft activity area
A glider operations area

The other page of the legend

Everything here sits on top of the airspace boundaries — the solid and dashed lines, the vignettes and the ceiling and floor figures. Those have their own drill, and the airspace area of the UAG practice test mixes both kinds of figure with the written questions that hang off them.

Airspace classes on a sectional Practise the airspace area

Frequently asked

What do the numbers next to a tower on a sectional chart mean?: Two heights in two datums. The upper figure is the elevation of the top of the obstruction above mean sea level; the figure in parentheses under it is the height of the structure above the ground. Part 107’s altitude limit in § 107.51(b) is written in feet above the ground, so the parenthesised figure is the one that talks to the rule — and within 400 feet of the structure it is the one the 400-foot allowance is measured from.
What is the difference between a magenta and a blue airport symbol?: Colour means tower. The Chart Users’ Guide: airports with control towers and their related data are shown in blue; all other airports and their data are shown in magenta. Since a towered airport almost always sits inside Class B, C or D, the colour is also the first hint that § 107.41 will require ATC authorization.
What is the large blue number with a small raised digit in each box of the chart?: The Maximum Elevation Figure. It is the highest elevation in that quadrant — terrain and obstacles included — in thousands and hundreds of feet MSL, rounded up to the next hundred with the last two digits dropped. A 3 with a raised 4 is 3,400 feet MSL. It is a ceiling on what is in the box, not the height of any one thing.
What is the difference between a restricted area and a restricted airport on a chart?: A restricted AREA is special use airspace: a blue hatched boundary labelled R and a number, such as R-4401, with invisible hazards like artillery firing inside it. A restricted or private AIRPORT is a magenta circle with an R inside it, charted as a landmark because it is not open to the public. They share a letter and nothing else.
What does VR1007 or IR21 on a sectional mean?: A military training route, flown fast and low by military aircraft. IR is flown under instrument rules regardless of weather, VR under visual rules. The number’s length is the read: four digits means no segment of the route is above 1,500 feet AGL; three or fewer digits means at least one segment is. The route can be several miles wide either side of the charted line.
How do I read the runway length from an airport’s data block?: It is the figure after the lighting code, in hundreds of feet — 72 is a runway of about 7,200 feet. The FAA rounds with 70 as the break point, so a runway of 8,070 feet is charted as 81 and one of 8,069 feet as 80, and the usable length may be less than the charted length.

Sources

Every figure on this page comes from one of the documents below, with the date it was read and what the document says about its own currency. Regulations change by amendment; where a source has moved on since the date shown, the source is right and this page is out of date.

FAA Aeronautical Information Services — Aeronautical Chart Users’ Guide Read September 5, 2026· Edition effective 9 July 2026 The authority for chart symbology, and the document the Remote Pilot Study Guide points at rather than reproducing. ⚠️ Added 2026-08-27 after an audit found two questions on this site sourced to the study guide for chart colours the study guide never states — the facts were right, the citation was not. Everything this site says about what a line or a colour MEANS on a sectional now comes from here.
FAA-G-8082-22 — Remote Pilot – Small Unmanned Aircraft Systems Study Guide Read September 5, 2026· August 2016 — predates Amendment 107-8 ⚠️ USE FOR SUBJECT MATTER, NEVER FOR A RULE. Airspace classes, METAR and TAF decoding, density altitude, load factor, physiology, radio procedure and airport data are unchanged and are sourced here. Its regulations chapter, its night rules and its silence on operations over people are all out of date, and a question sourced here on any of those is a bug.
14 CFR part 107 — Small Unmanned Aircraft Systems (eCFR) Read August 27, 2026· eCFR reports title 14 up to date as of 2026-08-25 The regulation itself, and the only acceptable source on this site for an operating limit, a category, an eligibility rule or a recency rule. Amendment 107-8 (86 FR 4381, 15 January 2021) is the one that rewrote night operations and added operations over human beings.

Page facts last verified September 5, 2026.

Part 107 Drills is independent practice material. It is not affiliated with, endorsed by, or authorized by the Federal Aviation Administration, PSI Services LLC, or any knowledge testing centre. Every question here is original and none is taken from any actual FAA knowledge test. Regulatory text and FAA publications are works of the United States Government and are in the public domain; where this site states a rule, it cites the section it came from and the date that section was read.