Collision Avoidance

Visual Scanning and Collision Avoidance


Relationship between a pilot’s physical condition and vision

  • Vision is affected by sleep, drugs, alcohol, and overall health

Environmental conditions that degrade vision

  • Haze
  • Smoke
  • Mist
  • Clouds
  • Volcanic ash
  • Dust
  • Sunset/sunrise
  • Cleanliness of windscreen
  1. Bugs
  2. Dirt
  3. Fingerprints
  4. Moisture
  • Sunglasses
  • Lighting conditions

Vestibular and visual illusions PHAK 16-6

  • The leans—bank too slow, fluid in ear canal doesn’t move
  • Corolis Illusion—when turning long enough, fluid slows to be moving at the same speed
  • Graveyard spiral—Corolis illusion tricks pilot to return to bank, compensates for loss of altitude by pulling up and tightens descending spiral
  • Somatogravic illusion—rapid acceleration feels like nose up
  • Inversion illusion—change from climb to straight-and-level feels like tumbling backward
  • Elevator illusion—abrupt upward (or downward) movement feels like a climb
  • Postural Considerations—seat of pants flying

“See and avoid” concept

  • Consistently be looking for traffic
  • Listen to and make radio calls to visualize where other aircraft are located; direction, speed, and altitude
  • Alter your path/speed/altitude if necessary to create adequate spacing with other aircraft

Proper visual scanning procedure

  • Scan the visual field in 10° increments, pausing at each section for a few seconds to notice any movement against the background

Relationship between poor visual scanning habits and increased collision risk

  • How many mid-air collisions do you think happen between two flight crews being vigilant in scanning for traffic and taking precautions to avoid others?
  • Divide your attention between the cockpit and outside, with the vast majority of attention going toward outside the aircraft

Proper clearing procedures

  • Clearing turns are usually at least 180° change in direction, looking for traffic (Jeppesen Private Pilot pg. 4-6)
  • A 90° turn in one direction and a turn back to the original heading has been deemed satisfactory
  • Be vigilantly scanning for traffic during these clearing turns

Importance of knowing aircraft blind spots

  • By understanding where you know you can’t see, you can maneuver the aircraft to see most of these areas.
  • There is a large portion behind and below the aircraft that is never seen from the cockpit, but clearing turns greatly reduce this void temporarily

Relationship between aircraft speed differential and collision risk

  • Imagine the difference between riding a pedal tricycle down the road verses a bullet bike.  The same bolting dog in the road would be more difficult to avoid on the fast bike.

Situations which involve the greatest collision risk

  • Where there is the most traffic
  1. Traffic patterns
  • Entering traffic pattern unaware of current traffic
  1. Approach to a busier airport
  2. Departure to common routes like Provo’s practice areas
  3. Enroute on popular Victor Airways
  • Clear cloudless beautiful days
  1. “It’s a great flying day today”—everyone and their dog seems to go flying on the days with beautiful weather
  2. Weekends commonly have more recreational traffic
  • Common departure and arrival times at international airports
  • Not all VFR traffic is talking with Air Traffic Control, or on the airport frequency

Conclusion and Evaluation:

It is important to understand the concepts to see and avoid other aircraft to maintain a good margin of safety between all aircraft in the sky.