AIRPORTS come in all sizes and shapes. Some are large complexes with numerous long, concrete runways that are more than two miles long. Most, however, like the one below, have only one or two hard-surface runways a few thousand feet long. Others can be short dirt or grass strips carved from the wilderness. Seaports are designated areas of water on rivers or lakes that are used by seaplanes. Heliports are small areas not much larger in area than the helicopters that use them.

A runway is numbered according to its magnetic direction. The direction is rounded off to the nearest 10 degrees and the last digit is dropped. For example, the runway in the diagram is aligned east (090°) and west (270°). It is numbered 9 and 27, depending upon the direction of takeoff and landing. If an airport has two parallel runways, they might be labeled 9L (for the left runway) and 9R (for the right runway). When operating in the opposite direction, they would be labeled 27R and 27L. When there are three parallel runways, the center runway usually is labeled with a “C” (e.g., 9C and 27C).

A TRAFFIC PATTERN is established to provide an organized flow of traffic about an airport. The standard traffic pattern in the United States is a left-hand pattern; the flow of traffic is counterclockwise. A right-hand (clockwise) pattern is used only when a left-hand pattern is impractical, such as when a portion of such a pattern would extend over a housing development. Using a right-hand pattern then places traffic on the other side of the airport and eliminates noise for those living under a left-hand pattern. The standard altitude at which airplanes fly in the traffic pattern varies from 600 to 1,500 feet above the airport elevation, but 1,000 feet is most common, and the altitude depends on local conditions and regulations. (The pattern altitude for military jets can be as high as 2,500 feet.)

A WIND INDICATOR, enclosed in a large, segmented circle, is displayed at most airports. The three common types above, for example, show the wind blowing from the east, indicating that takeoffs and landings should be made on Runway 9 (into the wind and toward the east). The L-shaped indicators show that the use of Runway 9 requires a left-hand traffic pattern. When the wind blows from the west, pilots use Runway 27 and fly a right-hand pattern. A northeast wind would indicate use of Runway 4, and so forth. Sometimes the wind “splits” the runways, and the pilot has a choice of which one to use.

WHEN DEPARTING from an airport without a control tower, the pilot looks at the wind indicator to determine which runway and what type of traffic pattern to use. The pilot taxis to the runway and, when ready for takeoff, visually scans the vicinity of the airport to see that no one is about to land.

UPON ARRIVING at an airport without a control tower, the pilot flies over the airport at least 1,000 feet above traffic pattern altitude to look at the wind indicator and determine which runway and what type of traffic pattern to use. The pilot then flies away from the area, descends to pattern altitude, and enters the flow of traffic at a 45-degree angle to the runway.

LARGE INTERNATIONAL AIRPORTS can look from above like complex spider webs of runways, taxiways, ramps, and terminal buildings. Some are as large as small cities. Chicago’s O’Hare International Airport has eight runways that total more than 74,000 feet in length.

The world’s busiest airport (in terms of passenger use) has consistently been the Hartsfield-Jackson International Airport in Atlanta, Georgia. The world’s largest airport (in square miles) is Saudi Arabia’s King Fahd International Airport.

Every airport has a unique three-letter location identifier. For example, pilots refer to Los Angeles International Airport as LAX, Seattle-Tacoma International Airport as SEA, and John F. Kennedy International Airport (serving New York City) as JFK. Airport identifiers in the contiguous United States are preceded by the letter K, such as KLAX, KSEA, KJFK, and so forth.

Pilots use airport diagrams to keep track of their position on the airport, keep their aircraft clear of conflict with other aircraft, and prevent them from crossing active runways without permission, a safety hazard called a runway incursion.

The next ASA Presents Author Talk will feature Captains Barry Schiff and Brian Schiff, who will discuss An Illustrated Guide to Flying and their combined love of flying. Watch live on October 12, 2023, at the ASA Presents website.

The post Airport Markings and Signs Illustrated first appeared on Learn To Fly.

These hot spot areas on the airport are found to be particularly complex and/or confusing and often times heavy traffic areas. Many times accidents, incidents, or runway incursions have been known to occur in these areas. The Chart Supplement U.S. will list a textual description of hot spots and a graphical depiction is shown on the Airport Diagram. Below is an example of a hot spot area for SUX airport labeled as HS-1. You can see that due to the crossing runways and taxiways this area could be rather confusing to a pilot not familiar with the airport.

By identifying hot spots, airport operators and air traffic controllers are able to plan for the safest possible movement of aircraft and vehicles operating on the movement area. As a pilot try to pre-plan your expected route to/from the runway and have a good idea of where your final destination is ahead of time and be aware of any hot spot areas which you might encounter. By making sure that aircraft surface movements are planned and properly coordinated with air traffic control, pilots add another layer of safety to their flight preparations.

Remember, the ultimate goal of hot spots is to prevent a ground based or runway incursion.

The post CFI Brief: Airport Hot Spot first appeared on Learn To Fly.

At airports without an operating control tower, a segmented circle visual indicator system, if installed, is designed to provide traffic pattern information. Usually located in a position affording maximum visibility to pilots in the air and on the ground and providing a centralized location for other elements of the system, the segmented circle consists of the following components: wind direction indicators, landing direction indicators, landing strip indicators, and traffic pattern indicators.

A tetrahedron is installed to indicate the direction of landings and takeoffs when conditions at the airport warrant its use. It may be located at the center of a segmented circle and may be lighted for night operations. The small end of the tetrahedron points in the direction of landing. Pilots are cautioned against using a tetrahedron for any purpose other than as an indicator of landing direction. At airports with control towers, the tetrahedron should only be referenced when the control tower is not in operation. Tower instructions supersede tetrahedron indications.

Landing strip indicators are installed in pairs and are used to show the alignment of landing strips. Traffic pattern indicators are arranged in pairs in conjunction with landing strip indicators and used to indicate the direction of turns when there is a variation from the normal left traffic pattern. (If there is no segmented circle installed at the airport, traffic pattern indicators may be installed on or near the end of the runway.)

At most airports and military air bases, traffic pattern altitudes for propeller-driven aircraft generally extend from 600 feet to as high as 1,500 feet above ground level (AGL). Pilots can obtain the traffic pattern altitude for an airport from the Chart Supplement U.S. Also, traffic pattern altitudes for military turbojet aircraft sometimes extend up to 2,500 feet AGL. Therefore, pilots of en route aircraft should be constantly on alert for other aircraft in traffic patterns and avoid these areas whenever possible. When operating at an airport, traffic pattern altitudes should be maintained unless otherwise required by the applicable distance from cloud criteria according to 14 CFR §91.155. Additional information on airport traffic pattern operations can be found in Chapter 4, “Air Traffic Control,” of the AIM. Pilots can find traffic pattern information and restrictions, such as noise abatement in the Chart Supplement U.S.

Example: Key to Traffic Pattern Operations—Single Runway

1. Enter pattern in level flight, abeam the midpoint of the runway, at pattern altitude. (1,000′ AGL is recommended pattern altitude unless otherwise established.)
2. Maintain pattern altitude until abeam approach end of the landing runway on downwind leg.
3. Complete turn to final at least ¼ mile from the runway.
4. After takeoff or go-around, continue straight ahead until beyond departure end of runway.
5. If remaining in the traffic pattern, commence turn to crosswind leg beyond the departure end of the runway within 300 feet of pattern altitude.
6. If departing the traffic pattern, continue straight out, or exit with a 45° turn (to the left when in a left-hand traffic pattern; to the right when in a right-hand traffic pattern) beyond the departure end of the runway, after reaching pattern altitude.

Example: Key to Traffic Pattern Operations—Parallel Runways

1. Enter pattern in level flight, abeam the midpoint of the runway, at pattern altitude. (1,000′ AGL is recommended pattern altitude unless otherwise established.)
2. Maintain pattern altitude until abeam approach end of the landing runway on downwind leg.
3. Complete turn to final at least ¼ mile from the runway.
4. Do not overshoot final or continue on a track that penetrates the final approach of the parallel runway
5. After takeoff or go-around, continue straight ahead until beyond departure end of runway.
6. If remaining in the traffic pattern, commence turn to crosswind leg beyond the departure end of the runway within 300 feet of pattern altitude.
7. If departing the traffic pattern, continue straight out, or exit with a 45° turn (to the left when in a left-hand traffic pattern; to the right when in a right-hand traffic pattern) beyond the departure end of the runway, after reaching pattern altitude.
8. Do not continue on a track that penetrates the departure path of the parallel runway.

The post Procedures and Airport Operations: Traffic Patterns first appeared on Learn To Fly.

Right of the bat you should take note that as an airport layout grows in complexity so will the signage associated with that airport. For example an airport with multiple runways will consist of a lot more signage then say an airport with one small runway. The reason being is more runways will require more taxiways and the greater likelihood for a runway or ground based incursion to occur. A pilot will need to pay a lot more attention at signage when operating at complex airports. In addition you will often see different types of signage at a Part 139 airport conducting commercial operations then you might at a small rural airport with no commercial operations.

There are six types of signs that may be found at airports.

Mandatory instruction signs—red background with white inscription. These signs denote an entrance to a runway, critical area, or prohibited area.

Location signs—black with yellow inscription and a yellow border, no arrows. They are used to identify a taxiway or runway location, to identify the boundary of the runway, or identify an instrument landing system (ILS) critical area.

Direction signs—yellow background with black inscription. The inscription identifies the designation of the intersecting taxiway(s) leading out of an intersection.

Destination signs—yellow background with black inscription and arrows. These signs provide information on locating areas, such as runways, terminals, cargo areas, and civil aviation areas.

Information signs—yellow background with black inscription. These signs are used to provide the pilot with information on areas that cannot be seen from the control tower, applicable radio frequencies, and noise abatement procedures. The airport operator determines the need, size, and location of these signs.

Runway distance remaining signs—black background with white numbers. The numbers indicate the distance of the remaining runway in thousands of feet.

The image below are further examples along with their action or purpose of the six types of airport signage discussed above. For further information on airport signage you can refer to the Aeronautical Information Manual (AIM) 2-3-7 or the Pilots Handbook of Aeronautical Knowledge, Chapter 14 Airport Operations.

The post CFI Brief: Airport Signage first appeared on Learn To Fly.

To land within a short-field or a confined area, the pilot must have precise, positive control of the rate of descent and airspeed to produce an approach that clears any obstacles, result in little or no floating during the round out, and permit the airplane to be stopped in the shortest possible distance.

The procedures for landing in a short-field or for landing approaches over obstacles as recommended in the AFM/ POH should be used. A stabilized approach is essential. These procedures generally involve the use of full flaps and the final approach started from an altitude of at least 500 feet higher than the touchdown area. A wider than normal pattern is normally used so that the airplane can be properly configured and trimmed. In the absence of the manufacturer’s recommended approach speed, a speed of not more than 1.3 V_SO is used. For example, in an airplane that stalls at 60 knots with power off, and flaps and landing gear extended, an approach speed no higher than 78 knots is used. In gusty air, no more than one-half the gust factor is added. An excessive amount of airspeed could result in a touchdown too far from the runway threshold or an after landing roll that exceeds the available landing area. After the landing gear and full flaps have been extended, simultaneously adjust the power and the pitch attitude to establish and maintain the proper descent angle and airspeed. A coordinated combination of both pitch and power adjustments is required. When this is done properly, very little change in the airplane’s pitch attitude and power setting is necessary to make corrections in the angle of descent and airspeed.

The short-field approach and landing is in reality an accuracy approach to a spot landing. The procedures previously outlined in the section on the stabilized approach concept are used. If it appears that the obstacle clearance is excessive and touchdown occurs well beyond the desired spot leaving insufficient room to stop, power is reduced while lowering the pitch attitude to steepen the descent path and increase the rate of descent. If it appears that the descent angle does not ensure safe clearance of obstacles, power is increased while simultaneously raising the pitch attitude to shallow the descent path and decrease the rate of descent. Care must be taken to avoid an excessively low airspeed. If the speed is allowed to become too slow, an increase in pitch and application of full power may only result in a further rate of descent. This occurs when the AOA is so great and creating so much drag that the maximum available power is insufficient to overcome it. This is generally referred to as operating in the region of reversed command or operating on the back side of the power curve. When there is doubt regarding the outcome of the approach, make a go around and try again or divert to a more suitable landing area.

Because the final approach over obstacles is made at a relatively steep approach angle and close to the airplane’s stalling speed, the initiation of the round out or flare must be judged accurately to avoid flying into the ground or stalling prematurely and sinking rapidly. A lack of floating during the flare with sufficient control to touch down properly is verification that the approach speed was correct.

Touchdown should occur at the minimum controllable airspeed with the airplane in approximately the pitch attitude that results in a power-off stall when the throttle is closed. Care must be exercised to avoid closing the throttle too rapidly, as closing the throttle may result in an immediate increase in the rate of descent and a hard landing.

Upon touchdown, the airplane is held in this positive pitch attitude as long as the elevators remain effective. This provides aerodynamic braking to assist in deceleration. Immediately upon touchdown and closing the throttle, appropriate braking is applied to minimize the after-landing roll. The airplane is normally stopped within the shortest possible distance consistent with safety and controllability. If the proper approach speed has been maintained, resulting in minimum float during the round out and the touchdown made at minimum control speed, minimum braking is required.

Common errors in the performance of short-field approaches and landings are:

• Failure to allow enough room on final to set up the approach, necessitating an overly steep approach and high sink rate
• Unstable approach
• Undue delay in initiating glide path corrections
• Too low an airspeed on final resulting in inability to flare properly and landing hard
• Too high an airspeed resulting in floating on round out
• Prematurely reducing power to idle on round out resulting in hard landing
• Touchdown with excessive airspeed
• Excessive and/or unnecessary braking after touchdown
• Failure to maintain directional control
• Failure to recognize and abort a poor approach that cannot be completed safely

The post Procedures and Airport Operations: Short-Field Approach and Landing first appeared on Learn To Fly.

When approaching the airport to enter the traffic pattern and land, it is important that the runway lights and other airport lighting be identified as early as possible. If the airport layout is unfamiliar, sighting of the runway may be difficult until very close-in due to the maze of lights observed in the area. Fly toward the rotating beacon until the lights outlining the runway are distinguishable. To fly a traffic pattern of proper size and direction, the runway threshold and runway-edge lights must be positively identified. Once the airport lights are seen, these lights should be kept in sight throughout the approach.

Distance may be deceptive at night due to limited lighting conditions. A lack of intervening references on the ground and the inability to compare the size and location of different ground objects cause this. This also applies to the estimation of altitude and speed. Consequently, more dependence must be placed on flight instruments, particularly the altimeter and the airspeed indicator. When entering the traffic pattern, always give yourself plenty of time to complete the before landing checklist. If the heading indicator contains a heading bug, setting it to the runway heading is an excellent reference for the pattern legs.

Maintain the recommended airspeeds and execute the approach and landing in the same manner as during the day. A low, shallow approach is definitely inappropriate during a night operation. The altimeter and VSI should be constantly cross-checked against the airplane’s position along the base leg and final approach. A visual approach slope indicator (VASI) is an indispensable aid in establishing and maintaining a proper glide path.

After turning onto the final approach and aligning the airplane midway between the two rows of runway-edge lights, note and correct for any wind drift. Throughout the final approach, use pitch and power to maintain a stabilized approach. Flaps are used the same as in a normal approach. Usually, halfway through the final approach, the landing light is turned on. Earlier use of the landing light may be necessary because of “Operation Lights ON” or for local traffic considerations. The landing light is sometimes ineffective since the light beam will usually not reach the ground from higher altitudes. The light may even be reflected back into the pilot’s eyes by any existing haze, smoke, or fog. This disadvantage is overshadowed by the safety considerations provided by using the “Operation Lights ON” procedure around other traffic.

The round out and touchdown is made in the same manner as in day landings. At night, the judgment of height, speed, and sink rate is impaired by the scarcity of observable objects in the landing area. An inexperienced pilot may have a tendency to round out too high until attaining familiarity with the proper height for the correct round out. To aid in determining the proper round out point, continue a constant approach descent until the landing lights reflect on the runway and tire marks on the runway can be seen clearly. At this point, the round out is started smoothly and the throttle gradually reduced to idle as the airplane is touching down. During landings without the use of landing lights, the round out may be started when the runway lights at the far end of the runway first appear to be rising higher than the nose of the airplane. This demands a smooth and very timely round out and requires that the pilot feel for the runway surface using power and pitch changes, as necessary, for the airplane to settle slowly to the runway. Blackout landings should always be included in night pilot training as an emergency procedure.

The post Procedures and Airport Operations: Night Flight Approaches and Landings first appeared on Learn To Fly.

The colors and color combinations that denote the type of airports are:

*Note: Green alone or amber alone is used only in connection with a white-and-green or white-and-amber beacon display, respectively.

A civil-lighted land airport beacon will show alternating white and green flashes. A military airfield will be identified by dual-peaked (two quick) white flashes between green flashes.

In Class B, C, D, or E airspace, operation of the airport beacon during the hours of daylight often indicates the ceiling is less than 1,000 feet and/or the visibility is less than 3 miles. However, pilots should not rely solely on the operation of the airport beacon to indicate if weather conditions are IFR or VFR.

The beacon has a vertical light distribution to make it most effective from 1–10° above the horizon, although it can be seen well above or below this spread.

Here is another nifty little tidbit you will learn once you start night flight training. Radio control of lighting is available at some airports, providing airborne control of lights by keying the aircraft’s microphone. The control system is responsive to 7, 5, or 3 microphone clicks. Keying the microphone 7 times within 5 seconds will turn the lighting to its highest intensity; 5 times in 5 seconds will set the lights to medium intensity; low intensity is set by keying 3 times in 5 seconds. Many airports, particularly airports without an operating control tower, will not keep runway lights on constantly throughout the night so it becomes the pilots responsibility to turn the runway lights on for landing or takeoff. Once the lights are keyed on they will typically remain on for 15 minutes. A quick glance in the Chart Supplement U.S. will identify an airport with pilot controlled lighting.

The post CFI Brief: Airport Rotating Beacon first appeared on Learn To Fly.

To assist pilots transitioning to a visual landing at the conclusion of a precision instrument approach, precision instrument runways have specific markings.

A displaced threshold on an instrument runway is indicated by arrows in the middle of the runway leading to the displaced threshold mark. The runway edge lights to the displaced threshold appear red to an airplane on approach, and to an airplane taxiing to the displaced threshold from the absolute end of the runway. They appear white when taxiing back from the displaced threshold toward the absolute end of the runway. The green runway end lights seen on approach to a runway with a displaced threshold are found off the edge of the runway.

The runway surface with arrows to the displaced threshold is available for taxiing, takeoff and landing roll-out, but not for landing. The initial part of this runway is a non-touchdown area. If chevrons rather than arrows are used to mark the displaced threshold, then the surface is not available for any use, other than aborted takeoff from the other direction.

A precision instrument runway will contain a designation, centerline, threshold, aiming point, touchdown zone, and side strips as seen in the figure below. Runway threshold strips can be configured in two ways. Four solid strips on either side of the centerline or configured as such that the number of strips correlates to the width of the runway (see table). The runway aiming point markers are large rectangular marks on each side of the runway centerline usually placed 1,000 feet after the threshold and serve as a visual aiming point for the pilot. Touchdown zone markers identify the touchdown zone for landing operations, providing coded distance information in 500 foot intervals and shown as either one, two, or three vertical stripes on either side of the centerline.

The post IFR: Precision Instrument Runway Markings first appeared on Learn To Fly.

The instrument landing system is known as the ILS. It enables a suitably equipped airplane to make a precision approach to a particular runway. A precision approach is one in which electronic glide slope guidance, as well as tracking guidance, is given. Each ILS is known by the airport and runway it serves, for example, the Lafayette ILS Rwy 10, in Indiana.

The instrument landing system has four main elements:

1. the localizer, which provides course guidance along the extended centerline of the runway (guidance in azimuth left or right of the extended centerline);
2. the glide slope, which provides vertical guidance toward the runway touchdown point, usually at a slope of approximately 3° to the horizontal, or 1:20 (vertical guidance above or below the glide slope);
3. marker beacons, which provide accurate range fixes along the approach path (usually an outer marker and a middle marker) are provided; and
4. approach lights, VASI (visual approach slope indicator), and other lights (touchdown zone lighting, runway lights, etc.) to assist in transitioning from instrument to visual flight.

There may be supplementary NAVAIDs available, including:

• a compass locator (NDB); and
• DME.

The outer marker may be replaced as a range marker on some ILS’s by a compass locator, a DME distance, or an ASR or PAR radar position from ATC. The middle marker, where more accuracy is required, may be replaced as a range marker on some ILS’s by a compass locator or PAR radar position from ATC (but not by a DME distance or ASR radar position). These range markers provide you with an accurate distance fix along the localizer.

A co-located compass locator and outer marker will appear on the approach chart as “LOM.” A co-located compass locator and middle marker will appear on the approach chart as “LMM.”

The ideal flight path on an ILS approach, where the localizer plane and the glide slope plane intersect, is referred to as the glide path. The word glide is really a misnomer carried over from earlier days, since modern airplanes make powered approaches down the glide path, rather than glide approaches. However, the term glide path is still used.

Since ILS approaches will often be made in conditions of poor visibility or at night, there is always associated visual information that can be used once the pilot becomes “visual” (has the runway environment in sight). This may include approach lights leading toward the runway, runway lights, touchdown lights, and centerline lights. Lighting is indispensable for night operations, but it can also be invaluable during daylight hours in conditions of restricted visibility.

There may also be a VASI situated near the touchdown zone to provide visual slope guidance during the latter stages of the approach. This, and other visual information, will assist you in maintaining a stable descent path toward the runway, where you can complete the landing.

The ILS is selected in the cockpit on the NAV/COM radio. Its cockpit display is usually the same instrument as for the VOR except that, in addition to the vertical localizer needle (CDI) that moves left and right for course guidance, there is a second needle or indicators that come into view. It is horizontal, and is able to move up and down to represent the position of the glide slope relative to the airplane. Some ILS indicators have needles that are hinged and move like wipers, others have needles that move rectilinearly. The airplane may be thought of as the center dot, and the intersection of the needles as the relative position of the glide path.

We’ll have more to share on the ILS, and much more on IFR, in future Monday posts.

The post IFR: The Instrument Landing System (ILS) first appeared on Learn To Fly.

Scanning by Day
The central (foveal) region of the retina provides the best vision, and in full color but only during reasonable daylight. Objects are best seen by day if you can focus their image on the foveal region, and you do this by looking directly at them. The most effective method of scanning for other aircraft for collision avoidance during daylight hours is to use a series of short, regularly spaced eye movements to search each 10° sector of the sky. Systematically focusing on different segments of the sky for short intervals is a better technique than continuously sweeping the sky. This is sometimes called the saccade/fixation cycle, where the saccade or movement takes about one-third of a second.

Relative Movement
If there is no apparent relative motion between you and another aircraft, you may be on a collision course, especially if the other aircraft appears to be getting bigger and bigger in the windshield. Due to the lack of movement across your windshield, an aircraft on a collision course with you will be more difficult to spot than one that is not on a collision course.

Any relative movement of an object against its background usually makes it easier to notice in your peripheral vision. The image of the other aircraft may not increase in size much at first, but, shortly before impact, it would rapidly increase in size. The time available for you to avoid a collision may be quite brief, depending upon when you see the other aircraft and the rate of closure.

If you are flying at 100 knots and it is flying at 500 knots in the opposite direction, the rate of closure is 600 knots, i.e. ten nautical miles per minute. If you spot the other aircraft at a distance of one nautical mile, you only have 1/10 of a minute (six seconds) to potential impact. If you are a vigilant pilot and spot it at 3 nautical miles you have eighteen seconds in which to act.

In hazy or low-visibility conditions, your ability to see other aircraft and objects with edges that might be blurred will be diminished and, if you can see them, they may appear to be further away than their actual distance. You might be closer than you think.

Empty-Field Myopia
When trying to search for other aircraft in an empty sky, the natural tendency of a resting eye is to focus at about six feet. Consequently, distant aircraft may not be noticed. To avoid this empty-field myopia, you should focus on any available distant object, such as a cloud or a landmark, to lengthen your focus. If the sky is empty of clouds or other objects, then focus briefly on a relatively distant part of the airplane like a wing tip as a means of lengthening your focus. Having spotted an airplane in an otherwise empty sky, be aware that it could be closer to you than it appears to be, because you have no other object with which to compare its size.

Specks
A small, dark image formed on the retina could be a distant aircraft, or it could be a speck of dirt or dust, or an insect spot, on the windshield. Specks, dust particles, a scratch, or an insect on the windshield might be mistaken for a distant airplane. Simply moving your head will allow you to discriminate between marks on the windshield and distant objects.

Scanning by Night
The central (foveal) region of the retina containing mainly cones is not as effective at night, causing an area of reduced visual sensitivity in your central vision. Peripheral vision, provided by the rods in the outer band of the retina, is more effective albeit color blind. An object at night is more readily visible when you are looking to the side of it by ten or twenty degrees, rather than directly at it. Color is not perceived by the rods, and so your night vision will be in shades of gray. Objects will not be as sharply defined (focused) as in daytime foveal vision.

The most effective way to use your eyes during night flight is to scan small sectors of sky more slowly than in daylight to permit off-center viewing of objects in your peripheral vision, and to deliberately focus your perception (mind) a few degrees from your visual center of attention (that is, look at a point but look for objects around it). Since you may not be able to see the aircraft shape at night, you will have to determine its direction of travel making use of its visible lighting:

• the flashing red beacon;
• the red navigation light on the left wing tip;
• the green navigation light on the right wing tip; and
• a steady white light on the tail.

Visual Judgment on Approach
The eyes and brain use many clues and stored images of known objects to help in judging distance, size and height. The relative size and relative clarity of objects give clues to their relative distances: a bigger object is assumed to be nearer than a smaller one and a more clearly defined object nearer than a blurry one. When the object is near, binocular vision (the slightly different images of a nearby object relative to its background seen by each eye) assists in depth perception.

Texture also assists in depth perception: the more visible the texture, the closer the object appears to be. On final approach as you near the aim point, the surface texture will appear to flow outward in all directions from the point on which you are focused. This is one means by which you can visually maintain the flight path to the aim point: adjust the attitude and heading so that the point from which the texture appears to be moving outward remains the desired aim point.

Texture is also used for the estimation of height; for instance, as you approach flare height for a landing, the actual texture of the runway or the grass passing by the cockpit becomes increasingly noticeable. Relative motion also aids in depth perception. Near objects generally appear to pass by faster than more distant objects. This helps a visual pilot estimate height above the runway before and during the flare: the closer the airplane is to the runway, the faster the runway surface and the surrounding environment appears to pass by.

Depth perception can be difficult in hazy or misty conditions, where edges are blurred, colors are muted, and light rays may be refracted unusually. This gives the impression of greater distance, an impression reinforced by the fact that we often have to look at distant objects through a smoggy or hazy atmosphere. This illusion is referred to as environmental perspective. In hazy conditions, the object might be closer than it seems; in very clear conditions, the object might be further away than it seems. On hazy days, you might touch down earlier than expected; on very clear nights, you might flare a little too soon.

The post Human Factors: Vision, Scanning, and Judgement first appeared on Learn To Fly.