VISUAL SCANNING AND COLLISION AVOIDANCE

Updated: Oct 7

Visual Scanning and Collision Avoidance Lesson by wifiCFI


Collision Avoidance

Be alert and scan for other traffic.

Right of Way Rules

Aircraft in distress

Balloon

Glider

Airship

Aircraft towing another aircraft

Airplane  and Helicopter


Essentially the aircraft with the least maneuverability is granted right of way.

Aircraft Converging

The aircraft to the right has the right of way

Approaching Head-On

When aircraft are approaching each other head-on, or nearly so, each pilot of each aircraft shall alter course to the right.

Overtaking

Each aircraft that is being overtaken has the right-of-way and each pilot of an overtaking aircraft shall alter course to the right to pass well clear.

Landing

Aircraft, while on final approach to land or while landing, have the right-of-way over other aircraft in flight or operating on the surface, except that they shall not take advantage of this rule to force an aircraft off the runway surface which has already landed and is attempting to make way for an aircraft on final approach. 

When two or more aircraft are approaching an airport for the purpose of landing, the aircraft at the lower altitude has the right-of-way, but it shall not take advantage of this rule to cut in front of another which is on final approach to land or to overtake that aircraft.

Spatial Disorientation

Spatial disorientation specifically refers to the lack of orientation with regard to the position, attitude, or movement of the airplane in space.

Vestibular system—organs found in the inner ear that sense position by the way we are balanced  

Somatosensory system—nerves in the skin, muscles, and joints that, along with hearing, sense position based on gravity, feeling, and sound 

Visual system—eyes, which sense position based on what is seen

Vestibular Illusions

The Leans

A condition called the leans, is the most common illusion during flight and is caused by a sudden return to level flight following a gradual and prolonged turn that went unnoticed by the pilot.

Coriolis Illusion

This occurs when a pilot has been in a turn long enough for the fluid in the ear canal to move at the same speed as the canal. 

A movement of the head in a different plane, such as looking at something in a different part of the flight deck, may set the fluid moving, creating the illusion of turning or accelerating on an entirely different axis.

Graveyard Spiral

As in other illusions, a pilot in a prolonged coordinated, constant-rate turn may experience the illusion of not turning. 

During the recovery to level flight, the pilot will then experience the sensation of turning in the opposite direction causing the disoriented pilot to return the aircraft to its original turn. 

Because an aircraft tends to lose altitude in turns unless the pilot compensates for the loss in lift, the pilot may notice a loss of altitude.

Somatogravic Illusion

A rapid acceleration, such as experienced during takeoff, stimulates the otolith organs in the same way as tilting the head backwards. 

This action may create what is known as the “somatogravic illusion” of being in a nose-up attitude, especially in conditions with poor visual references. 

Inversion Illusion

An abrupt change from climb to straight-and-level flight can stimulate the otolith organs enough to create the illusion of tumbling backwards, known as “inversion illusion.” 

Elevator Illusion

An abrupt upward vertical acceleration, as can occur in an updraft, can stimulate the otolith organs to create the illusion of being in a climb. 

This is known as “elevator illusion.” 

An abrupt downward vertical acceleration, usually in a downdraft, has the opposite effect with the disoriented pilot pulling the aircraft into a nose-up attitude.

Visual Illusions

False Horizon

A sloping cloud formation, an obscured horizon, an aurora borealis, a dark scene spread with ground lights and stars, and certain geometric patterns of ground lights can provide inaccurate visual information, or “false horizon,” when attempting to align the aircraft with the actual horizon.

Autokinesis

When flying in the dark, a stationary light may appear to move if it is stared at for a prolonged period of time.

Runway Width Illusion

A narrower-than-usual runway can create an illusion that the aircraft is at a higher altitude than it actually is, especially when runway length-to-width relationships are comparable.

A wider-than usual runway can have the opposite effect with the risk of the pilot leveling out the aircraft high and landing hard or overshooting the runway.

Runway Slope Illusion

An upsloping runway, upsloping terrain, or both can create an illusion that the aircraft is at a higher altitude than it actually is. The pilot who does not recognize this illusion will fly a lower approach. 

Downsloping runways and downsloping approach terrain can have the opposite effect.

Featureless Terrain

An absence of surrounding ground features, as in an overwater approach over darkened areas or terrain made featureless by snow, can create an illusion that the aircraft is at a higher altitude than it actually is. This illusion, sometimes referred to as the “black hole approach,” causes pilots to fly a lower approach than is desired.

Water Refraction

Rain on the windscreen can create an illusion of being at a higher altitude due to the horizon appearing lower than it is. This can result in the pilot flying a lower approach.

Haze

Atmospheric haze can create an illusion of being at a greater distance and height from the runway.

Fog

Flying into fog can create an illusion of pitching up.

Ground Lighting Lights along a straight path, such as a road or lights on moving trains, can be mistaken for runway and approach lights. Bright runway and approach lighting systems, especially where few lights illuminate the surrounding terrain, may create the illusion of less distance to the runway.  Scanning Technique

Scanning is more effective when you move your eyes in a series of short regularly spaced eye movements.


In doing so you should bring that area into your central focus for at least 1 second.


Each movement should not be more than 10 degrees.


Even if you have the right of way, yield if the other aircraft is too close.

Aircraft Blind Spots

High Wing:

The blind spots are above the pilot. 

A slight turn in the opposite direction can be made to clear above the aircraft before turning in the intended direction.

Low Wing:

The blind spots are below the pilot.

A slight turn the intended direction can be made to clear below the aircraft before committing to the turn in the intended direction.

Clearing Procedures

Before takeoff

Prior to taxiing onto a taxiway or runway, pilots need to clear the area. Scan for traffic approaching the airport or in the traffic pattern.

Climbs and Descents

When climbing and descending when you cannot see the airspace where you are going, make gentle left and right turns to clear the area.

Straight and Level

At regular intervals, pilots should execute appropriate clearing procedures.

Traffic Patterns

Entering the traffic patterns while descending should be avoided.

It is best to enter the traffic pattern on a 45 to the downwind leg.

VOR Sites

Due to converging traffic, be extra diligent around VOR sites and intersections.

Training Operations

Clearing procedures should be used when training and practicing flight maneuvers. During instruction the pilot should verbalize “clear left, clear right, above and below.”

Aircraft Type

High and low wing aircraft have their different blind spots. High wing aircraft should raise their wing to clear the area before turning. Low wing aircraft should lower their wing to clear the area prior to turning. Pilot Deviations Regulations do authorize pilot deviations under the following circumstances: Response to Traffic Alert and Collision Avoidance Systems

In an emergency

Pilot deviations can occur due to a lot of circumstances. Straying from heading or altitude to penetrating airspace without a clearance are just a couple examples. Ground Deviations

Includes taxiing, taking off, or landing without clearance, deviating from an assigned taxi route, or failing to hold short of an assigned clearance limit. How to protect against pilot deviations:

Plan each flight carefully. Become familiar with all pertinent information.

Talk and squawk.

Give plenty of room.

Avoid runway incursion situations.

Review NOTAMs and TFRs prior to each flight.

Write down instructions from ATC facilities.

Request “progressive taxi” when unsure.

Practice sterile cockpit procedures.

Land and Hold Short Operations What is a Land and Hold Short Operations (LAHSO)?


When an airplane is instructed (by ATC) to land and hold short of an intersecting runway or taxiway.


LAHSOs are NOT mandatory at anytime.


However, if a LAHSO is accepted by the pilot then he/she MUST comply with the LAHSO clearance.


Failure to do so could result in FAA penalty action and/or dangerous collision situations.

FAA Sources Used for this Lesson 14 CFR part 91

Aeronautical Information Manual (AIM)

Pilot’s Handbook of Aeronautical Knowledge (PHAK) Chapter 17


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