Airport Runway (RWY) Technical Glossary

Runway (RWY): Definition and Regulatory Framework

A runway (RWY) is a defined, rectangular area on an airport or aerodrome, specifically prepared for the takeoff and landing of aircraft. Runways may be constructed of various surfaces, including asphalt, concrete, grass, or gravel, and are designed to support the operational requirements of the largest and heaviest aircraft expected to use them. The geometry, surface, marking, and lighting of runways are extensively regulated by international standards, chiefly those of ICAO Annex 14 and FAA Advisory Circulars, to ensure uniform safety and operational efficiency worldwide.

Runway orientation is determined by prevailing wind patterns, maximizing headwind components to enhance safety during takeoff and landing. Each end of a runway is labeled with a designator based on its magnetic azimuth, rounded to the nearest ten degrees (e.g., RWY 09 for a 090° heading). Parallel runways are further differentiated by suffixes L (Left), C (Center), and R (Right). These designators are periodically updated to reflect changes in Earth’s magnetic variation.

Runways are the backbone of airport airside operations, with their dimensions, surface strength, and markings meticulously documented and maintained to meet the needs of commercial, cargo, and general aviation users.

Associated Runway Terms and Abbreviations

Threshold

The runway threshold marks the start of the portion of the runway suitable for landing. Identified by broad white stripes perpendicular to the centerline, it may be located at the physical end or displaced inward for safety or operational reasons.

Displaced Threshold

A displaced threshold is positioned away from the runway’s end to provide obstacle clearance or accommodate pavement limitations. The area before it can be used for takeoff and rollout, but not for landing touchdown in that direction.

Runway End

The runway end is the physical termination of the runway surface, marked by end lights and essential for accurate aeronautical data and instrument procedure design.

Stopway

A stopway is an area beyond the takeoff portion of the runway, aligned with the runway centerline, capable of supporting an aircraft in the event of an aborted takeoff. Marked by yellow chevrons, it is not intended for routine aircraft operations.

Runway Safety Area (RSA)

The RSA is an obstacle-free, graded surface surrounding the runway, designed to minimize damage in the event of an undershoot, overshoot, or excursion. Its dimensions and performance requirements are specified by ICAO and FAA.

Runway Designator

The runway designator is the number (and possible letter) identifying each runway end by its magnetic heading, with suffixes for parallel runways as needed.

Runway Centerline

The runway centerline is a white, dashed line running the length of the runway, providing essential alignment guidance for pilots during takeoff and landing.

Runway Markings

Runway markings encompass all permanent surface indications—numbers, centerlines, thresholds, aiming points, touchdown zones, side stripes, and shoulder markings—standardized for clarity and visibility.

Runway Holding Position

Runway holding positions are marked on taxiways at the runway edge, indicating where aircraft and vehicles must stop before entering a runway, enforced by surface markings and signage to prevent incursions.

Declared Distances (TORA, TODA, ASDA, LDA)

Declared distances are standardized runway length values:

• TORA (Takeoff Run Available): Usable runway length for takeoff ground run.
• TODA (Takeoff Distance Available): TORA plus clearway.
• ASDA (Accelerate-Stop Distance Available): TORA plus stopway for aborted takeoff.
• LDA (Landing Distance Available): Runway length suitable for landing.

These are essential for aircraft performance calculations and are published for each runway direction.

Runway Markings: Standards and Interpretation

Runway markings are regulated under ICAO Annex 14 and FAA AC 150/5340-1, all in white except for yellow shoulder/chevron markings. Markings vary by operational category (visual, non-precision, precision) and provide pilots with visual cues for alignment, touchdown, and maneuvering.

Threshold, aiming point, and touchdown zone markings are critical for safe and precise landings, especially in poor visibility.

Runway Lighting Systems and Visual Aids

Runway lighting is essential for operations in darkness or low visibility, standardized globally for pilot recognition and operational safety.

Runway Edge Lights

White (amber in the last 600m or half of the runway for instrument runways), outlining the runway edge. Types: HIRL (High), MIRL (Medium), LIRL (Low) intensity.

Runway Centerline Lights

Embedded, spaced every 15m, white until the last 900m where they alternate red and white, then all red in the final 300m, warning of the runway end.

Threshold and End Lights

Threshold lights are green (start of runway for landing); end lights are red (runway end for departure).

Runway End Identifier Lights (REIL)

Synchronized flashing white lights at each side of the threshold, rapidly identifying runway ends, especially in poor visibility.

Touchdown Zone Lights (TDZL)

White lights embedded from the threshold for 900m or to the runway midpoint, whichever is less.

Visual Approach Slope Indicator (VASI) and Precision Approach Path Indicator (PAPI) systems provide glidepath guidance with red and white lights to show if the approach is above, on, or below optimal.

Runway Design, Configuration, and Declared Distances

Runway Design Parameters

• Orientation: Based on wind analysis and magnetic heading.
• Length/Width: Determined by the largest aircraft, operational minima, and regulatory standards.
• Surface: Asphalt, concrete, or stabilized gravel, selected for operational demand and climate.

Runway Identifiers

Numbers correspond to magnetic heading. Parallel runways use L/C/R suffixes. Headings and designators are updated as magnetic variation shifts.

Declared Distances

Clearway: Obstacle-free area beyond runway for takeoff acceleration.
Stopway: Paved area beyond runway for aborted takeoff.

Declared distances are published in the AIP, airport diagrams, and pilot briefings.

Runway Operations and Procedures

General Operational Requirements

Strict control of runway operations is essential. At towered airports, ATC clearance is required before entering or crossing any runway. At non-towered airports, pilots must self-announce and adhere to published traffic patterns.

Traffic Patterns and Standard Procedures

Standard patterns include departure, upwind, crosswind, downwind, base, and final approach legs, ensuring safe sequencing of arrivals and departures.

Landing clearance is mandatory at controlled airports. At uncontrolled airports, pilots must visually confirm runway status and broadcast intentions.

Runway Usage Limitations and Digital NOTAMs (AIXM)

Temporary or permanent runway changes (closures, restrictions, conditional access) are communicated via NOTAMs, increasingly in digital AIXM format for real-time updates. Restrictions may be based on time, aircraft type, or operation, and are critical for flight planning and safety.

Runway Safety Areas and Protection Zones

Runway Safety Area (RSA)

The RSA is a vital safety buffer, extending at least 150 meters from the centerline and 90 meters beyond the end for large runways, graded and obstacle-free to support aircraft and emergency vehicles in case of undershoot, overrun, or excursion.

Summary

Runways are the core of airport operations, engineered and maintained to strict international standards for geometry, surface, markings, lighting, and declared distances. Their design, operation, and ongoing management are critical to aviation safety and efficiency, supporting everything from small general aviation flights to the largest commercial aircraft.

For detailed regulatory references and diagrams, consult ICAO Annex 14, FAA Advisory Circulars, and your national Aeronautical Information Publication (AIP).