AC 90-48D

Pilots' Role in Collision Avoidance (AC 90-48D)

Advisory Circular 90-48D describes the pilot's role in collision avoidance, including see-and-avoid techniques, scanning methods, visual limitations, and procedures for maintaining vigilance in high-traffic areas. It emphasizes that collision avoidance is ultimately the pilot's responsibility regardless of ATC services.

Download Free PDF View on FAA.gov

Why This Document Matters

This AC drives home one of aviation's fundamental truths: see-and-avoid is every pilot's responsibility, even when receiving radar services. It covers the physiology of vision, effective scanning techniques, blind spots, and how closure rates affect your ability to see and react to conflicting traffic. The knowledge test frequently asks about scanning methods and the limitations of human vision in detecting other aircraft.

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

VFR practice in a busy training area. Your CFI says 'watch for traffic' and you confidently say 'sure.' 4 minutes later you glance at the GPS, look back up, and realize you have NO idea where the Cessna that was at your 2 o'clock just went. You haven't seen it in 90 seconds.

Stage 2

Decision

How do you actually scan? Block method, side-to-side, or something else? How often should your eyes leave the panel? What are your blind spots in this aircraft, and how do you check them?

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

Stage 3

Targeted Learning

Open only these sections of the AC 90-48D:

Chapter on See-and-Avoid Responsibilities (pilot always responsible, even with ATC)
Chapter on Scanning Techniques (block method, 10-15° segments, minimum 1-sec focus)
Chapter on Visual Limitations (empty-field myopia, glare, small aircraft size)
Chapter on Closure Rates (head-on at 120 KIAS each = <10 sec to impact)

Stage 4

Debrief

Compare your Decision to what the handbook says:

?Block scan: 10-15° segments, 1 second each. Did you pause long enough, or just swing your eyes?
?Empty-field myopia: eyes default to ~6 ft of focus with no reference. Do you actively refocus on distant objects?
?Closure rate at 120 KIAS + 120 KIAS head-on = ~4 NM/minute = 15 seconds from dot-to-collision. Does your scan cycle beat that?
?Blind spots: high-wing cockpit has upper-pattern blind spots; low-wing has lower. Which way does your airplane hide traffic?

Stage 5

Reinforcement

Turn your biggest miss into fast-recall rules:

Block scan: 10-15° segments, minimum 1 second per block, systematic (not random).
Traffic closure rate: co-altitude head-on traffic at 120 KIAS each = ~15 seconds warning. Scan accordingly.
ATC traffic advisories are helpful, not a substitute. You are always the final line of defense against a collision.

What Order to Read the AC 90-48D

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

Survival Thinking

“What can hurt me?”

•See-and-avoid is every pilot's responsibility regardless of ATC services
•Blind spots per aircraft type (high-wing vs. low-wing, shoulders, behind)

Interpretation

“What am I looking at?”

•Block scanning technique
•Recognizing collision-course geometry (constant bearing, decreasing range)

Prediction

“What will happen?”

•Closure rate calculations and visual detection time budgets

Checkride Mode

“Can I explain it under pressure?”

•DPE will observe your scan — random vs. systematic is visible from the right seat
•Be able to describe your scan technique out loud

Chapter-by-Chapter Guide

What each section covers and the key topics to study

See-and-Avoid Responsibilities

Pilot responsibility for collision avoidance, limitations of ATC services, and right-of-way rules.

Key Topics

Pilot responsibility under 14 CFR 91.113Limitations of radar traffic advisoriesRight-of-way rules

Visual Scanning Techniques

Effective scanning methods, human vision limitations, and high-risk collision scenarios.

Key Topics

Block scanning techniqueEmpty field myopiaClosure rates and reaction timeHigh-risk areas (practice areas, VORs, traffic patterns)

Study Tips

Learn the block scanning technique: move your eyes in segments across the visual field, pausing at each block to focus. The human eye can't detect traffic in peripheral vision alone.
Understand empty field myopia — when there are no distant objects to focus on (clear skies), your eyes tend to focus at a resting distance of about 10-30 feet, making distant traffic invisible.
Know the right-of-way rules in 14 CFR 91.113 cold — especially that aircraft in distress have right-of-way over ALL other aircraft.

Frequently Asked Questions

If I am receiving flight following, is ATC responsible for collision avoidance?

No. Even when receiving VFR flight following or radar traffic advisories, the pilot-in-command remains responsible for see-and-avoid collision avoidance. ATC provides traffic advisories on a workload-permitting basis, but this does not relieve the pilot of the responsibility to scan for traffic.

What is the most effective visual scanning technique?

The block scanning technique is most effective. Divide the visual field into segments of about 10-15 degrees, pause at each block for at least one second to allow your eyes to focus, then move to the next block. This systematic approach covers more area than random scanning.

Quick Facts

Document ID: AC 90-48D
Last Updated: 1983
Cost: Free
Publisher: FAA

Applies To

StudentPrivateInstrumentCommercialCFI

Download PDF

Study Smarter

Get AI-powered study tools that turn the AC 90-48D into interactive flashcards, practice questions, and personalized study plans.

Try VectoredOps Free

No credit card required

Master These Documents with AI-Powered Learning

VectoredOps turns FAA handbooks into interactive study tools. AI-generated flashcards, practice oral exams, and spaced repetition help you retain what you read.