Taxiway (TWY) – Airport Operations Glossary

Definition

A taxiway (TWY) is a designated, paved path on the surface of an airport, established for the safe ground movement of aircraft between runways, terminals, aprons, hangars, and other airport facilities. Unlike runways, which are intended for takeoff and landing, taxiways are used exclusively for ground maneuvering of aircraft and, in some cases, authorized airport vehicles.

Taxiways are built to rigorous international and national standards—such as ICAO Annex 14 and FAA AC 150/5300-13—governing their width, pavement strength, markings, lighting, signage, slopes, and their separation from obstacles and other movement areas. Their design must accommodate the largest aircraft expected to use them, ensuring operational safety for all users.

Taxiways feature distinctive yellow markings, blue edge lights, green centerline lights, and a system of signs to guide pilots and ground vehicles. Their identification, such as “Taxiway Alpha (A)” or “Taxiway Bravo 1 (B1)”, is crucial for air traffic control (ATCT) communication and ground traffic management.

Key Taxiway-Related Terms & Acronyms

Purpose and Function of Taxiways

Taxiways are critical for the safe, efficient, and orderly movement of aircraft on the ground. They:

• Connect runways, terminals, aprons, and hangars.
• Facilitate optimal routing to minimize ground delays and reduce runway occupancy.
• Support simultaneous movements, segregate arrivals and departures, and prevent bottlenecks.
• Provide access for ground service and emergency vehicles.
• Are engineered for the weight, size, and turning requirements of the largest expected aircraft.

Air Traffic Control Tower (ATCT) manages all aircraft and authorized vehicle movement on taxiways, issuing clearances to prevent collision and ensure smooth operation.

Technical Characteristics of Taxiways

Design Standards

Taxiway design is governed by standards from organizations like ICAO and FAA. Key parameters include:

• Width: Based on Airplane Design Group (ADG); e.g., 25 ft for small aircraft (ADG I), up to 82 ft for widebody jets (ADG V).
• Shoulders: May extend 10–30 ft or more for added safety and to prevent jet blast erosion.
• Pavement Strength: Must support the maximum aircraft weight, using PCN/ACN reporting.
• Separation Distances: Ensure safe margins between taxiways, runways, and obstacles.
• Slopes: Longitudinal and transverse slopes are limited to ensure drainage and safe maneuvering.

Example Table: Taxiway Groups

Markings and Signage

• Centerline Markings: Solid yellow lines guide taxiing.

• Edge Markings: Double solid yellow lines mark pavement edges.

• Holding Position Markings: Two solid and two dashed yellow lines at runway/taxiway intersections.

• Signage:

  • Location (black/yellow)
  • Direction (yellow/black & arrows)
  • Mandatory (red/white)
  • Information (yellow/black)

• Lighting:

  • Blue edge lights
  • Green centerline lights (at larger airports)

Operational Use of Taxiways

Taxiing Procedures

• ATCT clearance is required before entering taxiways.
• Pilots must read back hold short instructions.
• Aircraft follow centerlines for clearance.
• Speed limits: typically 20 knots straight, slower in turns.
• At holding positions, pilots stop and await clearance.

Usage Limitations

• Closures: Due to construction, maintenance, or hazards.
• Conditional Use: May restrict certain aircraft or require special coordination (e.g., WTCE).
• Time-Limited Restrictions: Specific hours for closures, often in NOTAMs.

Sample NOTAM:
“Taxiway Tango (TWY T) is a Group III taxiway and can accommodate aircraft with a wingspan up to 117 feet. Self-powered aircraft operations are prohibited for aircraft with wingspan of 118 feet and greater on TWY T.”

Types and Configurations

• Parallel Taxiways: Run alongside runways for efficient access.
• Stub Taxiways: Short connectors to aprons, hangars.
• High-Speed Exits: Allow rapid runway exit at shallow angles.
• Holding Bays: Enlarged areas for holding or run-ups.

Taxiway Safety and Compliance

Safety Areas

• Taxiway Safety Area (TSA): Graded, obstacle-free zone extending beyond taxiway edges to protect veering aircraft.

Incursion Prevention

• Standardized markings, signage, and lighting.
• ATCT procedures for positive control.
• Advanced Surface Movement Guidance and Control Systems (A-SMGCS) at large airports.

Construction & Maintenance Impacts

• Phased closures and operational restrictions are common.
• Barricades, closure markings, and alternate routes are implemented.
• NOTAMs and detailed planning minimize disruption.

Examples and Use Cases

Aircraft Movement

A Boeing 737-800 taxis from gate to runway via Taxiway A and B, following ATCT clearances, centerline markings, and holding at the required positions.

Taxiway Usage Limitation

A digital NOTAM restricts Taxiway Charlie (TWY C) to emergency use during repairs, impacting flight planning and real-time taxi routing.

Wing Tip Clearance Escort

For oversized aircraft, a WTCE is coordinated, with a ground team escorting the aircraft to ensure safe passage and obstacle clearance.

Construction Phasing

Major taxiway reconstruction is conducted in phases, with temporary closures, alternative routes, and continuous coordination to ensure operational continuity.

Regulatory and Compliance Considerations

Design and Operation Standards

• FAA AC 150/5300-13: US design and operational standards for taxiways.
• ICAO Annex 14: International standards for taxiway dimensions, markings, and safety.
• Additional local requirements may apply.

NOTAMs and Notifications

• All status changes, closures, and restrictions must be published via NOTAM.
• Digital NOTAMs, using Aeronautical Information Exchange Model (AIXM), ensure timely and accurate information distribution.

Summary

Taxiways (TWY) are essential for safe, efficient airport operations—guiding aircraft between runways and airport facilities, supporting ground traffic management, and ensuring compliance with strict safety standards. Robust design, clear markings, lighting, and real-time communication via ATCT and NOTAMs are fundamental for ground movement safety and operational excellence.

For more on taxiway design, safety, or operational optimization, contact our airport operations team or schedule a demo .