Pilot's Role in Collision Avoidance
Collision Avoidance
Advisory Circular 90-48E
Remember Herb's Rules to Live By:
1. Use a Checklist.
2. Look outside
3. Never fly hard IFR in a single engine aircraft
Visual Scan and Collision Avoidance
-Most midair collisions occur near airports, during daylight hours and in VFR conditions. Early detection is crucial to avoiding collisions, since it takes about 12.5 seconds to realize you are on a collision course and to do something about it.
-Degraded physical condition = degraded vision.
-Environmental conditions such as night time and low visibility degrade vision.
-Vestibular and visual disturbances can create motion and visual illusions.
-Spend 2/3 to 3/4 of scan time outside cockpit.
-Proper visual scanning procedures, eye movements of 10 degrees, focusing one to two seconds on each segment of the sky, 60 degrees left and right, 10 degrees up and down. Day=central vision, night=peripheral. Know that central focal vision is severely degraded at night, so peripheral vision is needed.
-“See and avoid” concept requires vigilance be maintained at all times, regardless whether the operation is IFR or VFR.
-Poor scanning = increased collision risk.
-Proper clearing procedures in all phases of flight.
-Know your aircraft’s blind spots. Turn on all lights in the pattern, and keep in mind that folks using night vision systems may not see all of those lights due to wavelengths outside the NVS operating specifications.
Hanger Talk: There is something special about flashing the wing lights or ground handling lights at night at another aircraft that is off in the distance, like ships passing at sea. A special hello to fellow aviators.
-Know your blind spot, located in the central focal vision where the optic nerve attaches. That is why traffic that is on a constant bearing, decreasing range to your aircraft "suddenly appear." One example is the 2025 nighttime collision near KDCA Reagan National airport.
-Aircraft speed differential and collision risk, converging at 300 knots = 36 seconds to react.
-Greatest collision risk: Airways, VORs, within 25 nm of airports, enroute, at or below 8,000 feet, day, VMC.
“Clear left, clear right, above and below”
-Slow down and live is one defensive tactic, especially in the pattern.
-"Look with your ears" also, listen to radio calls to build situational awareness of where the traffic is. If a tower is running split frequency operations with customers on both VHF and UHF frequencies, our awareness needs to be higher than whatever the highest level is.
From the Advisory Circular:
"13.1 Scanning at Night. Scanning at night depends almost entirely on peripheral vision. This is due in part to the night-blind spot that involves an area between 5 and 10 degrees wide in the center of the visual field. A pilot can compensate for the night-blind spot through “off-center” viewing, which requires looking approximately 10 degrees above, below, or to either side of an object. To better perceive a dimly lit object in a certain direction, the pilot should scan the area around the object rather than looking directly at the object. Short stops of a few seconds in each scan will help detect the light and its movement. Note that conflicting ground lights at night increase the difficulty of detecting other aircraft. Also, avoid blinding others while taxiing by not using strobe or landing lights until on the active runway for takeoff.
