Visual scan & blind spots
Eye limits:
- Field not seen with equal clarity.
- Eye perceives very poorly while in motion.
- Wide, sweeping movements: almost useless, a hazard. Feel thorough, leave gaps.
- Use short, regularly spaced movements.
Sector scanning (standard method):
- Divide sky into about 30-degree segments.
- Start in middle of windshield.
- Scan slowly across each segment, pausing in its centre.
- Sweep the two left segments, then snap back to begin right-hand segments.
| Coverage | Extent |
|---|---|
| Horizontal | about 150 degrees (full field of vision) |
| Vertical | 10 degrees above and below horizontal, where most traffic sits |
Identifying a target (3 steps): pick it up, lock on, recognize it.
| Target on windshield | Meaning |
|---|---|
| Moves, drifts across | Easy to see. Probably clear |
| Holds still | Collision course: appears stationary until the last few seconds. Hardest to detect. Needs avoidance plan |
Empty-field myopia:
- Cause: haze, dark, or featureless sky. Eyes relax, focus at near point, about 3 to 5 ft (TC sample exam Q36 key).
- Fix: look for distant lights to refocus.
Scan degraded by: fatigue, boredom, illness, anxiety, preoccupation (scanning shares attention with every other flying task).
Closing speed (two light aircraft, each 120 KT, head-on = 240 KT closing):
| Sighted at | Time to decide and act |
|---|---|
| 3 miles | 45 seconds |
| 1 mile visibility | 15 seconds, often less (traffic usually spotted well inside visibility range) |
Blind spots (structure hides traffic):
- Blind spot beneath every aircraft. Nose-up attitude enlarges it: forward visibility drops.
| Wing | Blind |
|---|---|
| High-wing | In direction of turn, as soon as bank is applied |
| Low-wing | Beneath it |
Most dangerous geometry (neither pilot can see the other):
- Low-wing descending from the rear toward a high-wing aircraft
- High-wing climbing from the rear toward a low-wing aircraft
Clearing: small turns in prolonged climbs and descents to clear above and below.
Trap: treating a stationary windshield target as "not a threat because it isn't moving". No motion is the collision-course signature, not the all-clear. Also assuming the other pilot has seen you: every aircraft has a blind spot.
References
- TP 1102 Ex.5 Attitudes and Movements, Look-out
- TP 1102 Ex.23 Pilot Navigation, Avoiding a Collision
- TP 1102 Pilot Navigation, Avoiding a Collision
- TC sample exam Q36 (empty-field myopia)