Runway Centerline and Edge Line Explanation PDF

RUNWAY CENTERLINE - is a prominent marking on a runway at an airport, and it plays a crucial rolein guiding aircraft during takeoff and landing. The centerline is typically marked on the runway's surface using white paint or other highly visible materials. It is a continuous line that...

RUNWAY CENTERLINE - is a prominent marking on a runway at an airport, and it plays a crucial rolein guiding aircraft during takeoff and landing. The centerline is typically marked on the runway's surface using white paint or other highly visible materials. It is a continuous line that extends the full lengthof the runway. Instrumentation: Modern airports may have advanced systems, suchas Instrument Landing Systems (ILS) and Precision Approach Path Indicators (PAPI), that work in conjunction with the centerline to help pilots maintainthecorrect approach and descent path during landing. RUNWAY EDGE LINE - The primary purpose of the runway edge line is to define the lateral boundaries of the runway. It marks the edges or sides of the runway surface andprovides a visual reference for pilots to determine the runway's width. Low-Visibility Operations: Runway edge lights are often installed alongtheedge line. These lights help guide pilots during low-visibility conditions, suchas fog or night operations, by providing a clear outline of the runway's boundaries Safety Purpose: It ensures that aircraft stay within the designated runway surfaceand do not veer off into the surrounding areas, which could be hazardous. Clearance and Safety Zones: The runway edge line also demarcates thebeginning of clearance and safety zones. These zones are areas that must be kept clear of obstacles to ensure the safety of aircraft in the event of an overrunor undershoot during takeoff or landing. RUNWAY NUMBER - also known as the runway designation or runway identifier. Runway Orientation: The runway number is based on the magnetic compass direction in degrees. It represents the approximate magnetic heading of therunway in tens of degrees. For example, if a runway's magnetic headingis approximately 090 degrees, the runway number would be 09. If the headingis approximately 270 degrees, the number would be 27. Directional Information (RUNWAY NUMBER EXTENSION) The runwaynumber is accompanied by a letter (L, C, or R) to indicate the specific runwayif there are multiple runways with the same number at an airport. These letters standfor Left, Center, and Right, respectively. For example, if there are three parallel runways at an airport with magnetic headings of 090 degrees, they maybedesignated as 09L (Left), 09C (Center), and  09R (Right). Precision and Non-Precision Runways: In some regions, runways withprecision instrument approach systems like ILS (Instrument Landing System) areoften given numbers ending in "1" (e.g., Runway 01 or Runway 19). Non- precision runways may have numbers ending in "9" (e.g., Runway 09 or Runway27). Parallel Runways: At airports with parallel runways, the runway numbers areused to indicate the relative positions of the runways. For example, if there aretwo parallel runways, one aligned with a magnetic heading of 090 degrees andthe other with 270 degrees, they might be designated as Runway 09 and Runway27. RUNWAY THRESHOLD - is a section of a runway that is marked and designated as unsuitable for aircraft landing but can be used for other operations, such as taxiing, taking off, or landing roll out after touchdown. Purpose: Obstacle clearance A displaced threshold ensures that aircraft have sufficient clearance to safely descendover these obstacles by shifting the point at which they can land further downtherunway. Noise abatement Noise-sensitive areas: In some cases, displaced thresholds are used to reduce noiseover residential or sensitive areas close to the runway Increased safety margins Extended rollout area: For landing aircraft, the displaced threshold can still be usedas a rollout area after touchdown, giving them more distance to decelerate. This increases safety in the event of a high-speed or long-landing roll out. AIMING POINT - also known as the aiming point markers or touchdown zone markers, is a set of visual markings or lights on a runway designed to assist pilots during the landingphase of an aircraft's approach. The aiming point serves as a reference for pilots tohelp them accurately align the aircraft for a safe and smooth landing. Location: The runway aiming point is typically located a specific distance downthe runway from the threshold (the beginning of the runway) and is usually found within the first 3,000 feet (approximately 900 meters) of the runway's length. Its exact placement can vary from one runway to another based on various factors, including the airport's design and the approach angle. Visual Markings: Often consist of a series of large, conspicuous whiterectangles or bars painted on the runway. These bars are positionedsymmetrically and are typically situated in pairs, with  one pair on each side of therunway centerline. Lighting: In addition to painted markings, some runways are equipped withrunway aiming point lights. These lights are embedded in the runway surface andare typically sequenced or strobed to provide visual cues to pilots during their approach. They may be white or red in color. Purpose: The primary purpose of the runway aiming point is to assist pilots indetermining the correct altitude and descent rate as they approach the runwayfor landing. By aiming for the markers or lights, pilots can help ensure that theaircraft touches down in the desired touchdown zone. This contributes to a safeand controlled landing. Safety and Precision: Landing within the designated touchdown zone is important for various reasons, including ensuring that the aircraft has sufficient runway length for stopping, minimizing wear and tear on the runway surface, andavoiding runway overruns or undershoots. TOUCHDOWN ZONE - is a specific area on a runway where an aircraft's main wheels or landinggear is intended to make initial contact with the runway during the landing phase. This zone is marked and designated to facilitate safe and precise landings. Location: The touchdown zone is typically located at the beginning of therunway, near the threshold (the start of the runway). Visual Markings: Usually consist of a series of large, conspicuous whiterectangles or bars painted on the runway surface. These bars are positionedsymmetrically on each side of the runway centerline. AIMING POINT VS TOUCHDOWN ZONES (The aiming point serves as a reference for aligning the aircraft during the descent, while the touchdown zone designates the specific area on the runway where the initial landing contact should occur.) DISPLACED THRESHOLD - It is an area at the beginning of the runway that is not intended for aircraft toland on or take off from. Instead, it is meant for other operational purposes, suchas reducing the impact of noise on nearby communities, avoiding obstacles, or accommodating taxiing aircraft. Purpose: Obstacle Clearance: One common reason for having a displaced threshold is toprovide additional clearance from obstacles, such as buildings, trees, or terrain, that might otherwise obstruct the flight path of landing or departing aircraft. Noise Abatement: In some cases, airports implement displaced thresholds toreduce aircraft noise impact on nearby residential areas. Safety: Displaced thresholds can enhance safety by ensuring that aircraft haveadequate distance to  achieve the necessary speed and altitude for takeoff or landing, especially when there are terrain or obstacle concerns. Aircraft Separation: At airports with intersecting runways, displaced thresholds on one runway can create separation from the other runway, allowing for safer operations. BLAST PAD -also known as an overrun area or blast pad area, is a specialized sectionof arunway or taxiway at an airport designed to enhance safety during takeoff and landingoperations, particularly for aircraft with powerful jet engines. Blast pads areengineered to withstand the powerful jet blast generated by aircraft engines duringtakeoff, which can create high levels of turbulence, noise, and debris. Purpose: Jet Blast Mitigation: The primary purpose of a blast pad is to mitigate theeffects of jet blast, which can be particularly strong when aircraft with high-thrust engines, such as large commercial jets, take off. Jet blast can cause safety hazards, damage to structures, and runway debris to be blown into the air. Noise Reduction: Blast pads can also help reduce the noise generated byjet engines during takeoff. By allowing the aircraft to be farther away frompopulated areas and structures, noise impacts on nearby communities canbeminimized. Foreign Object Debris (FOD) Control: The blast pad area is designedtominimize the risk of debris being sucked into an aircraft's engines during takeoff or blown onto the runway, which could pose safety hazards.