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.
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.
Chapter-by-Chapter Guide
What each section covers and the key topics to study
1See-and-Avoid Responsibilities
Pilot responsibility for collision avoidance, limitations of ATC services, and right-of-way rules.
See-and-Avoid Responsibilities
Pilot responsibility for collision avoidance, limitations of ATC services, and right-of-way rules.
Key Topics
2Visual Scanning Techniques
Effective scanning methods, human vision limitations, and high-risk collision scenarios.
Visual Scanning Techniques
Effective scanning methods, human vision limitations, and high-risk collision scenarios.
Key Topics
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
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Pilots' Role in Collision Avoidance (AC 90-48D) is an official FAA publication available at FAA.gov
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