AC 90-66C

Non-Towered Airport Flight Operations (AC 90-66C)

Advisory Circular 90-66C provides guidance for operations at non-towered airports including traffic pattern procedures, radio communication practices, and right-of-way rules. It covers standard traffic pattern entry and departure, recommended communication phraseology on CTAF frequencies, and procedures for handling conflicts at airports without air traffic control.

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Why This Document Matters

Most airports in the United States are non-towered, and this AC is the definitive guide to operating at them safely. It covers standard traffic pattern entry (45-degree to downwind), straight-in approaches, communication on CTAF/UNICOM frequencies, and how to handle conflicting traffic. The 2023 revision (C) updated guidance on traffic pattern operations and clarified several long-debated topics. Every pilot should be familiar with this AC, especially for the practical test where DPEs expect proper non-towered procedures.

Study This Document in One Loop

What is the Study Loop?

A 30-60 minute scenario-first session that replaces hours of passive reading.

Stage 1

Scenario

Non-towered field, CTAF is busy. You're on 45° entry to downwind for 27 when someone announces "straight-in final runway 27, 3 mile." Another aircraft announces "upwind, turning crosswind." You're #3 on frequency clutter and can't see either aircraft. Pattern altitude is 1,000 AGL, field elevation is 800 MSL.

Stage 2

Decision

Do you continue the 45° entry, extend downwind, or break off? Which aircraft has right-of-way and under what rule? What's your exact next radio call?

Write your answer before you open the handbook. That exposes the gap.

Stage 3

Targeted Learning

Open only these sections of the AC 90-66C:

Chapter on Traffic Pattern Operations (45° entry, pattern altitude, extending vs. breaking off)
Chapter on Radio Communications (position reporting, conflicting calls, NORDO)
Chapter on Right-of-Way (aircraft on final has priority; straight-in is discouraged but legal)

Stage 4

Debrief

Compare your Decision to what the handbook says:

?Aircraft on final has right-of-way. Where does "straight-in" fit when you're on 45° to downwind?
?Position report: "Smalltown traffic, Skyhawk 1234X, [position], [altitude], [intentions], Smalltown." Did you close with the airport name?
?NORDO aircraft: they have right-of-way too. How do you see-and-avoid if they're not on frequency?
?Self-announce vs. two-way with other traffic: when is it appropriate to coordinate directly on CTAF?

Stage 5

Reinforcement

Turn your biggest miss into fast-recall rules:

Standard pattern = 1,000 AGL, left traffic. Confirm direction on sectional or Chart Supplement — some fields use right traffic.
45° entry to mid-downwind at pattern altitude is the FAA-recommended standard for non-towered fields.
Always close CTAF calls with airport name (frequency shared across airports — ambiguity kills).

What Order to Read the AC 90-66C

Don't read by chapter number. Work the four phases. Start with whichever you're weakest in.

Survival Thinking

“What can hurt me?”

•Right-of-way rules (aircraft on final, aircraft lower/slower, NORDO vs. radio-equipped)

Interpretation

“What am I looking at?”

•CTAF phraseology and position reporting format

Prediction

“What will happen?”

•Predicting other traffic from CTAF calls — building a mental picture of the pattern

Checkride Mode

“Can I explain it under pressure?”

•DPE will quiz on pattern entry, proper CTAF calls, and right-of-way scenarios
•Know when "straight-in" is acceptable and how to announce it

Chapter-by-Chapter Guide

What each section covers and the key topics to study

Traffic Pattern Operations

Standard traffic pattern entry and departure procedures, pattern altitude, and right-of-way.

Key Topics

45-degree entry to downwindStandard left-hand traffic patternPattern altitude (1,000 AGL typical)Right-of-way rules

Radio Communications at Non-Towered Airports

CTAF procedures, recommended phraseology, position reporting, and AWOS/ASOS usage.

Key Topics

CTAF frequency usageSelf-announce proceduresPosition reports (10mi, entering pattern, each leg, final, clear of runway)UNICOM vs CTAF vs MULTICOM

Study Tips

Know the standard traffic pattern entry: overfly midfield at pattern altitude + 500 feet, then descend into a 45-degree entry to the downwind leg.
Practice self-announce radio calls — the format is always: airport name, your aircraft type and call sign, position, and intentions.
Understand when a straight-in approach is acceptable and when the 45-degree entry is preferred — this is a common DPE discussion topic.

Frequently Asked Questions

Are radio calls required at non-towered airports?

Radio communications are not legally required at non-towered airports (unless in Class E surface area or other specific situations), but they are strongly recommended by the FAA. AC 90-66C provides the recommended procedures. Operating NORDO (no radio) is legal but requires extra vigilance and doesn't exempt you from right-of-way rules.

What is the standard traffic pattern altitude?

The standard traffic pattern altitude is 1,000 feet above ground level (AGL) for propeller-driven aircraft and 1,500 feet AGL for large or turbine-powered aircraft. Check the Chart Supplement (A/FD) for any airport-specific traffic pattern altitudes.

Quick Facts

Document ID: AC 90-66C
Last Updated: 2023
Cost: Free
Publisher: FAA

Applies To

StudentPrivateInstrumentCommercialCFI

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