Airport Information

Runways

There are a variety of runway types and markings. They range from sophisticated Instrument Landing System runways to small grass strips. The FAA has established a standard set of markings identifying the characteristics of the runway. Markings for runways are white. Markings on taxiways, closed or hazardous areas, and holding positions are Yellow.

Runway Markings

A number of standardized markings exist on the surfaces of paved runways. The runway markings identify whether the runway is equipped for Precision or Non-precision Instrument Approaches (IFR), or whether only Visual approaches are allowed (VFR). A combination of the following marking elements are used.

• Runway Number Designation
• Centerline Marking
• Threshold marking
• Aiming Point
• Touchdown Zone
• Side Stripes

Runway Numbering

Runway numbers and letters are determined based on the approach direction to the runway. The number is the whole number nearest one-tenth the magnetic azimuth of the runway centerline. For example, a runway with a magnetic heading from 035° through 044° is numbered 04. The third digit of the magnetic heading is dropped. The range of numbers is from runway 01 through 36.

The letters “L”, “C”, or ”R” is added to the number to identify the runway as being the left, center, or right runway respectively. At some very large airports, there may be one set of parallel runways on one side of the airport (say 27L and 27R). On the other side of the airport, another set of runways may exist with just one number difference (28L and 28R).

Centerline Marking

The runway centerline identifies the center of the runway. It is comprised of evenly spaced white line stripe and unpainted gaps. The centerline provides visual alignment during takeoff and landing.

Runway Aiming Point Marker

These markings are white rectangular line segments located on each side of the centerline, located approximately 1000 feet down the runway from the threshold. They serve as a visual aiming point for landing aircraft.

Touchdown Zone Markers

These markers are white stripes identifying the touchdown area of the runway. They are coded in groups of one, two and three rectangular bars, spaced 500 feet apart down the runway. The grouped bars are symmetrically placed on each side of the runway centerline.

Threshold Markings

They are longitudinal stripes located at the threshold end of the runway. There are usually eight bars, but wide runways may have a different configuration. They identify the beginning of the runway surface suitable for landing.

Side Stripes

These are continuous white lines along the edge of the runway to delineate the edge of the runway from surrounding terrain or other surfaces.

Runway Types

There are three types of paved runways. Each has a different set of markings. They are:

• VFR Runways
• Non-precision Instrument Approach Runways
• Precision Instrument Approach Runways

VFR Runways

The runway threshold shown identifies a VFR only runway. It contains a runway number and an aiming point marker on each side.

Non-Precision Instrument Approach Runways

Runways with non-precision instrument approaches are similar to the VFR runway with the addition of threshold markings.

Precision Approach Runway

A precision Approach Runway is one equipped with a full ILS capability.

The precision approach runway markings exist on runways equipped with ILS approach or other precision approach methods. Besides the non-precision markings, additional markings exist.

• Touchdown zone marking
• Line (ILS Hold Yellow lines)
• ILS Hold Sign (white ILS on red background)

Other Runway Markings

A Number of markings are used to indicate unusable runway and airport areas. These are: Displaced Threshold Unusable Surface Closed Runway

Displaced Thresholds

Some runways have displaced thresholds marked with white arrows leading to the threshold line. The area with the arrows maybe used for taxi and takeoff, but not for landing. On landing, the wheels of the aircraft should not touch the runway before crossing the lateral threshold line.

There can be a number of reasons for the threshold displacement. The end of the runway may be too close to a road or other obstructions or hazards. The displaced area may not have sufficient runway strength to sustain the impact of landing aircraft.

Unusable Areas

An area containing yellow chevrons depict areas that cannot be used either for taxi, takeoff or landing. Often they are older or inadequate runway sections or used as an overrun area. They may be at either the approach or overrun end of the runway.

Closed Runway

An X on a runway indicates the runway is closed. It has become dangerous due to structural or other reasons. Use may be hazardous.

Taxiways

Taxiways provide paved surfaces connecting the parking ramps to the runways. Their centerlines are marked with a continuous yellow line. If the edge of the taxiway is marked, two yellow lines 6 inches apart are used.

VFR Holding Line

Holding positions where aircraft must hold before crossing or entering the runway are marked by two dashed yellow lines nearest the runway, and two solid yellow lines are furthest from the runway. There may also be a white runway number on a red painted square located in front of the double solid lines.

Do not cross until clearance is given by the tower at a controlled airport. At an uncontrolled airport, do not cross the solid lines until all aircraft are clear of the runway, no aircraft is on final approach. When taxiing to a runway, do not cross the solid lines until final approach, and it is determined that takeoff can be performed safely.

ILS Critical Holding Area

At larger airports where ILS instrument approaches are being made, taxiing aircraft should hold at the ILS Holding position line. The lines are yellow in color. A red ILS Holding sign will be along side the taxiway at this point. If the tower has instructed you to hold at the ILS Holding Line you should not taxi beyond this point until cleared by the tower.

Airport Signs

There are 5 types of signs used on airports. They are:

• Mandatory Instruction Signs
• Location Signs
• Direction Signs
• Destination Sign
• Runway Distance Remaining Signs

Mandatory Instruction Signs

These signs are White lettering on a Red background.

Holding position signs are used on taxiways that intersect runways at a point other than at the runway end. Holding position signs are also located at the yellow hold line on the taxiway at the end of the respective runway. It may be necessary to hold aircraft at a position on the taxiway other than at the runway end. These holding points prevent interference with landing or departing aircraft.

An ILS Critical Holding Area sign is used on taxiways serving a Precision Instrument Approach runway. It is used to hold departing aircraft farther from the ILS runway when instrument landings are in progress. It will be co-located with the ILS critical area taxiway marking.

A No Entry sign is used on taxiways with “one-way” traffic only, or at intersection with roadways that could be confused for a taxiway.

Location Signs

Location signs are advisory in nature. They are yellow characters on a black background. They provide visual assistance to pilots in determining location on the runway or taxiway, and helps them determine when they have exited an area.

• Taxiway Location Signs: Alphabetic letters identifying taxiways.
  
• Runway Identification Signs: This runway identification sign indicates the runway number on which the aircraft is located.

Direction Signs

These are signs of a general informative nature. They show exits to runways, directions to parking ramps, etc. They are black letters or markings on a yellow background.

Taxi Boundary Sign

This is a runway boundary sign, as seen by the pilot exiting a runway onto the taxiway. The aircraft is “clear” of the runway after it has taxied beyond this sign.

ILS Critical Area Boundary Sign

This is an ILS Area Boundary sign. When the aircraft is exiting the runway, it is “clear” of the ILS Critical Area when past this sign. The sign is co-located with the ILS Critical marking on the taxiway.

Exit Signs

Direction signs show how to exit from an intersection. When used on a runway to indicate an exit, the sign is on the same side as the exit. They are black letters on a yellow background.

Destination Signs

These signs are black letters on a yellow background. They usually contain an arrow pointing to the destination, such as General Aviation Ramp, Terminal, Parking Area, etc.

Information Signs

They provide the pilot of about such things as areas hidden from the control tower view, applicable radio frequencies, and noise abatement procedures. The airport operator determines the need, size and location for these signs.

Runway Distance Remaining Signs

Runway distance remaining signs have white numbers on a black background. They are placed along side some runways to indicate remaining runway in thousands of feet.

Other Sign and Lighting Information

Landing Indicators

A number of different wind and landing indicators are in use at airports. Virtually all airports have one or more of these indicators.

A segmented circle will be located near the center of the airport. The "L" shaped ears indicate landing pattern direction. The red cone is called a wind sock and indicates wind direction. The Tetrahedron (T) indicates the runway in use. It is usually manually set.

Wind Indicators

• Wind Sock - This is a cone shaped fabric indicator showing the wind direction. It also provides some measure of the wind velocity. The large open end of the cone faces the wind. Wind entering the open end fills the cone with air and it becomes more erect. The direction of the wind is from the large toward the small end of the cone. If the wind is calm, the cone will be limp. As wind velocity increases, the cone becomes more erect (in a horizontal direction).
• Wind Tee - (not shown) This looks like a small airplane with a body, vertical tail fin, and a wing. It orients with the wind with the wing on the upwind side and the tail downwind. The direction of the wind tee suggests the landing direction.
• If there is no wind indicator, observe smoke from factories, ground fires, etc. These will indicate wind direction. Also, the lee side of a lake (upwind direction) tends to be smooth.

Landing Indicators

A device called a Tetrahedron at some airports indicates the active runway. It is a pointed triangular shaped object shown in the diagram above as (T). One end configured in a long point (the front end). The rear end has a short, blunt triangular shape. Most are lighted to be visible at night. It is usually set into a fixed position by the airport personnel to indicate landing direction. It does not necessarily indicate true wind direction. The pilot should not rely on a tetrahedron as a wind indicator. Some are fixed and are not free to swing with the wind.

Segmented Circle

A dashed circle known as that Segmented Circle ( shown below) is located in a position near the center of the airport. A wind cone, a tetrahedron or wind tee will be contained inside the circle. Outside the circle are landing traffic pattern indicators (the “L” shaped objects).

Assume that there are 2 runways at this airport; one 9 - 27 (East/West) and the other 18 - 36 (South/North) The tetrahedron is set to indicate landing on runway 9 to the East. The wind cone indicates the wind from the Southeast. The pattern indicators show the required direction of flight on the Base and Final legs of the approach to the runway. Departure flight pattern is defined by the pattern indicator for the departure end of the runway.

The traffic pattern indicators specify a left hand pattern for runways 9 (landing east shown by the indicator at the left) and 36 (landing north shown by the indicator at the bottom). The other indicators specify a right hand pattern for runways 27 (landing west as shown by the indicator on the right) and 18 (landing south as shown by the indicator on the top)

Traffic Pattern

The pattern of traffic around a non-controlled airport is as shown below.

An aircraft taking off eastward on runway 9 and staying in the traffic pattern will turn Crosswind (position 5) at approximately 400 feet above the runway, then Downwind to fly parallel the runway as shown at number 2 at an altitude approximately 800 feet above the runway. (Note: Some airports designate the pattern altitude to be 1000 feet.). Then when past the end of the runway will turn to Base between positions 2 and 3, while descending. The aircraft will the turn to Final at position 3. This is known as a Standard Left Hand Pattern. Also, according to the pattern indicators, a pattern for runway 36 is left hand. The downwind leg is on the west side of the airport, with all turns to the left.

The pattern indicators indicate landings on Runways 27 and 18 are right hand patterns. The downwind leg for runway 27 is north of the airport, with all turns to the right. Landing on 18, the downwind leg will be west of the airport, with all turns to the right.

Aircraft outside the pattern should enter the pattern approximately at mid point of the airport at a 45° angle to downwind (position 1). Aircraft leaving the traffic pattern should depart anywhere from “straight out" (position 6) to “crosswind” (position 5. A right turn departure from a left hand pattern is prohibited.

At airports with parallel runways, left hand pattern is used on the left runway; a right hand pattern is used on the right runway.

Traffic patterns at controlled airports with an operating control tower follow generally the same procedures. However, since the tower controller is responsible for traffic separation within the tower jurisdiction, the controller may grant or require other procedures. In all cases, except emergency, obey the controllers' instructions. The traffic pattern at tower-controlled airports is usually 1000 feet Above Ground Level (AGL).

Airport Lighting

Runway Lighting

A lighted airport has runway lights situated on both sides of the runway. Some systems are able to operate at High (HIRL) Medium (MIRL) and Low (LIRL) intensity. Many airports have the lighting off during certain night hours, and the pilot must make active by clicks of the microphone. The intensity of HIRL and MIRL runway lights can be controlled by personnel on the ground. The pilot can control the intensity by clicking the microphone on the published Common Traffic Advisory Frequency (CTAF) for the airport. It takes 7 clicks to turn lights to high, 5 to medium, and 3 for low. Some airports may only provide medium and/or low brightness.

Taxiway Lighting

Taxiways edge lights are blue, and are on at night and during the day at times of reduced visibility. At larger airports, the tower personnel can control the intensity of the lights. Also, some taxiways may have imbedded green lights along the centerline of the taxiway. They are on during times of reduced visibility to mark the way between the runways and ramp areas.

Approach Lighting

There are numerous approach light systems at large airports with Instrument Landing Systems. These are beyond the scope of the beginning private pilot, and will not be addressed in detail in this material.

Several approach light systems are of interest to the VFR pilot. These are:

• Runway End Identifier Lights (REIL)
• Visual Approach Slope Indicators (VASI)
• Precision Approach Slope Indicators (PAPI)
  

Runway End Identifier Lights (REIL)

Visual Approach Slope Indicators (VASI, PAPI)

There are several forms of VASI’s. All employ lights that indicate a correct slope(s) for approach to landing. They may be used both for day and night operation. They provide an “on slope” glide slope angle of approximately 3°. The 2 bar VASI has 2 ranks of lights. Each rank may consist of one light or two lights side by side. You are “on glide slope” as shown in the center diagram (red over white). You are too high if both ranks are white, as on right. You are too low then both ranks are red as shown on left. The 3 bar VASI has 3 ranks of lights, The two center show “on glide path” indications. The leftmost is a low path, and the rightmost is a high path. The all red is too low. The all white indication is too high.

Airport Beacons

Rotating beacons which operate at night and during times of poor weather assist the pilot to locate the airport from the air.

Wake Turbulence

All aircraft generate some turbulence, called Wake Turbulence. The turbulence from small aircraft is of little consequence. When the size and weight of the aircraft are great, the turbulence can be severe to other aircraft.

Cause

A number of factors contribute to wake turbulence. These are slipstream turbulence, jet blast, propeller wash, and wingtip vortices. The most severe of these disturbances is Wingtip Vortices. To over simplify, they are small tight horizontal tornadoes of air leaving the wing tips. The turbulence is a byproduct of the wing creating lift.

A pressure differential is created between the upper and lower surface of the wing. The low pressure is on the upper surface. This pressure differential creates a rolling airflow at the wing tip inward toward the fuselage. The rotating air mass trails rearward. The right vortex rolls counterclockwise; the left vortex is clockwise.

Vortex Avoidance

Wingtip vortices have certain predictable characteristics. A large aircraft generates vortices from the moment of takeoff rotation. Takeoff rotation causes significant vortex.

In flight, the sink rate of the vortices is 400 to 500 feet per minute, and levels out 900 to 1000 feet below the aircraft. Near the runway surface, a tailwind can cause the vortex to persist near the ground for several minutes if the wind is light.

Large heavy aircraft generates significant vortex on landing. It has a high angle of attack of attack, and is slow and heavy. The point of greatest wing loading and vortex is the flare to touchdown. This is due to additional wing load caused by centrifugal force generated in the flare.

When operating on and near large airports with large aircraft operations, caution concerning wake turbulence must be observed. The strength of the wingtip vortices is greatest then the aircraft is HEAVY, CLEAN and SLOW. The greatest hazard to small aircraft is coming across a vortex while operating near the ground.

Each vortex is about 2 wingspans in width and one wingspan in depth. They remain spaced about one wingspan apart, drifting with the wind. In a no-wind situation, the vortices will persist on the runway. They move laterally outward about 2 to 3 knots on each side when striking the ground.

A cross wind will add or subtract from the natural 2 - 3 knot lateral movement of each vortex. With a light crosswind component of about 3 knots, the upwind vortex can persist for a considerable time. The vortex movement and the opposing crosswind produce a stationary vortex.

STAY ABOVE AND UPWIND FROM THE VORTEX.

Plan your strategy accordingly:

1. When landing on the same runway behind a large aircraft, stay at or above the larger aircraft’s approach path. Note the touchdown point, and plan to land beyond that point. 2. If landing on a runway parallel to and within 2500 feet of one being used by a large aircraft, use the same procedure as in 1 above. 3. If landing on a runway crossing the larger aircraft’s runway, cross the other runway above the large aircraft’s flight path.
4. Land well short of a large departing aircraft’s rotation point.
5. If a large aircraft is departing a crossing runway, note the rotation point of the large craft.
· If rotation is past the intersection, continue to land as you would normally.
· If it rotates before the intersection, avoid flight below the aircraft’s flight path. Execute a missed approach unless you are sure you can stop well before the intersection.
6. If departing behind a departing large aircraft, note the rotation point of the departing aircraft. Become airborne before the rotation point, and stay higher and upwind of the larger aircraft’s flight path. If unable, request the control tower for a change in flight direction away from the path of the larger aircraft.
7. If you takeoff at an intersection, be cautious that your departure path will not cross under the path of a larger aircraft.
8. You should ensure an interval of at least 2 minutes before takeoff or landing across or behind the path of a large aircraft that has executed a low pass, touch-and-go, or a missed approach.
9. Avoid flight below the path of a larger aircraft when enroute at altitude. Try to stay above or upwind of larger aircraft near your altitude.

Other Airport Operations Data