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AI.II.B.K6FAA-S-ACS-25 · Nov 2023Knowledge

Visual cues of an impending mid-air collision.

ACS element text (the applicant demonstrates understanding of)

Visual cues of an impending mid-air collision.

Bottom line

The 'see-and-avoid' concept has long been the foundation of midair collision prevention. High closure rates from aircraft performance in speed and rates of climb and descent limit the time available for detection, decision, and evasive action.

Key numbers

Key numbers for Visual cues of an impending mid-air collision.
NumberWhat it means
not exceed 10°Eye movement
at least 1 secondDwell time

FAA references

  1. AC 90-48, para. 7.1 — AC No: 90-48E
  2. AFH ch. 1 (p. 1-10) — FAA-H-8083-3C
  3. PHAK ch. 14 (p. 14-28) — FAA-H-8083-25C (2023)
  4. RMH ch. 3 (p. 3-8) — FAA-H-8083-2A
  5. RMH ch. 6 (p. 6-2) — FAA-H-8083-2A
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